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INORGANIC CHEMISTRY Chief Editor & Compiler: .~~~!!>m..",,~.
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ABHISHEK
Warren Carmen
All rights reserved. No part of this book may be reproduced in 'any form, electronically or otherwise, in print, photoprint, micro film or by any other means without written permission from the publisher.
ISBN ISBN
Copyright First Edition
i
: 978-81-8247-050-7 I
)
:
81-8247-050-/ ~
Publisher 2009
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Preface The subject of inorganic chemistry deals with chemical compounds that do not contain hydrocarbon radicals. It is the specialised branch of chemistry and is the complex one. This makes it a tremendous task, to present the dictionary in such a way that it is well received by the community who are very much concerned with the subject. This dictionary is infact, is formulated in such a way that everybody, either s/he is a student, a teacher or a researcher. This dictionary contains .more than 2000 well researched, ,exhaustively and are precisely explained. The descriptions are described in the simplest of the language. Many of the terms in the dictionary are also supplemented with the visual representations. These visual representations help the readers to grasp the point behind the definitions very easily and without any fuss. These visual representations provide supplementary knowledge to the readers rather than emphasising what already is given in the text. This different methodology will certainly help the readers of this dictionary to get an edge over others who are pursuing different paths.
~4~~~~~.~~~~~II All in all with so much of hard work being involved in the formulation of this book, we hope that this venture will certainly find it's niche in the reader's mind and reader will find it their best companion in their quest of exploring the field of Inorganic Chemistry.
II = = = = = = = = = = = = = 1norg''''" Chemistry
~ spectrum of a substance is ob; tained by passing a beam of : light through the substance in ~ a spectrometer and examining ~ the light that emerges. When a ; substance is capable of emitting : a spectrum, the lines of the I .. . - absorption . enusslon spectrum are m exabsorption is the process ; actly the same positions as the whereby a gas is taken up and : lines and bands in the absorp. dispersed in the bulk of a solid :I non spectrum. or a liquid, or where a liquid is I taken up and dispersed in the : - abundance of substances ~ the abundance of substances. is body of a solid. . ; the ratio of the total mass of a • absorption spectra ; specified element in the earth's absorption spectra result from : crust to the total mass of the the interaction of electromag- I earth's crust. It is often exnetic radiation with matter, ; pressed as a percentage. where the energies that are removed from the continuous ; • acid spectrum oflight by the absorp- ; an acid is defmed as a substance tion medium show up as black ~ which contains hydrogen that lines or bands. The absorption ~ can be displaced by a metal with ; the liberation of hydrogen gas : and the formation of a salt. ~ An understanding of the I chemical mechanisms that ; give rise to the properties of : acids evolved from a number L .......~..--. ~ of different theories of the 400 500 eco I nature of acids. Arrhenius rp.xIN of 1M ,bfl"f" ,........' , f·fttlH l)nd. ; proposed the Arrhenius Con,..n. Boww..I:<,. MO/ton. JOJlS.!.} : cept of Bases that an acid is a
- absolute zero of temperature the absolute zero of temperature is the lowest temperature on the thermodynamic scale of temperature and is -273°C.
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ItI.01'lJllnic Chemistry
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11
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substance which provides hy- ~ drogen ions as a result of dis- ; sociation and ioniSation in : . I aqueous soI utIon. Lewis pro- : posed the Lewis Theory of ~ Acids that there is a recipro- ; cal relationship between acids : and bases, and he introduced ~ the concept of Lewis Conju- ~ gate Acid-Base Pairs.; Bronsted and Lowry proposed ~ the Bronsted Lowry Theory of: Acids that acids are proton ~ donors and that bases are pro- ; ton acceptors. :
.
rutroge~ in ~e air is normally
uncreatIve, rutrog~n oxides ~re also produced durmg ~e high temperature combustion process. SulRhur dioxide and niI trogen OXIdes, NO, are toxic • acid or acyl halides ~ a<=!-dic gases which r~adily react these are organic compounds : ~lth the water in the atmocontaining the group -CO. X ~ sphere to form a mixture of , where X is a halogen . Acyl ~ s~phuric ~cid, nitric acid and chlorides, have the general' rutrous aad. The dilute soluI. f formula R.CO.Cl. In systemi- : tions 0 ~ese acids which result cally naming acyl halides the ~ g~~ ram water a ~ar greater names end with the suffix -oyl, I aCIdity than ~o~ (I.e. a lower e.g. ethanoyl chloride; pI:I+~dthisl~kn.ownasacid CH COCl. : ram. Jacld-base mdicators acid3 I base Indicators are used when • ~cid ~ain ; acid is vitrated_against a base ~ad ram results from the burn- : m Volumetric Analysis, to give mg of fossil fuels containing ~ a visual indicavion of the endsulphur, when sulphur dioxide ; point of the titratlcon. An acidis produced during the combus- : base indicator usually"changes . tl~n process. Although the :I coIour over a range of abowt 2
:m
I
II = = = = = = = = = = = = I'""lJlJnic Chemistry
II a&id-hllSe titmtion I aeids anJhases • pH units. Each indicators change colours at a different and unique"pH. .. . • aCid-base tItratIon an acid-base titration is the an~lyrical technique in Vol~etnc Analysis , where an aCId of known concentration is used to neutralise a known volume"of a base, and the ob~erv~d volume of the acid reqtured IS used to determine the unknown c~ncentration ofvhe base. An aCldbase indicator is used to d~termine the end-point of the tttration. • acid anhydrides those oxides which form acidic solutions on reaction with water are called ccidic oxides, (or sometimes acid anhydrides). The acidic oxides are thg oxides of the non-metal elements. The acid anhydrides are called b{ their systematic names (e.g. sulpjur dioxide, nitr?~en ~ntoxide,etc.).MostaCldicoXides are soluble in water and react with it giving ackds in sol~ti~n. For example, slllphwr triOXide reacts with water to profuce sulphuric acid.
I'""1llJnic Chemistry
~~~~~~~~~~=7 ~ S03+~0
==>
~S
; All acidic oxides react with : alkalks to give salt and water ~ only. For example, sulp.hur I trioxide"reacts with sodIUm : hydroxide in asueous solution ~ to produce sodium sunphate ~ and water. ; SO + 2 NaOH = = > : Na 3S04 + H 0 2 ~ Sidtilarly, nitric oxide reacts I with sodium hydroxide in aque~ ous solution to produce a ~_ : ture ofsodium nitrate, sodium ~ nitrite and Water. ; 2NO + 2NaOH ==> 2 : NaN02 + NaN03 + ~O ~ Acidic oxides also include the ~ giant molecular lattices (e.g. ; silicon dioxide). ~ • acids and bases : when the oxides of non-metals ~ reacted with water they formed I acids. For cxamplg, when sul: phur dioxide is dissolved in wa~ tef an acidic solution of Sul~ ph~ous Acid results. S02 .+ ; HO ==> H S0 • Siml2 3 : la:l~ the oxides of metals react ~ with watgr to form bases. For ~ example, when sodium oxide ; reacts with water, sodium hy-
=======.....======__ II
8
•
aetinUles IlIIiIlitUmpol~
II
droxide (i.e. caustic sodc) is ~ toovercometheenergybarrier. . formed. N 0 __ ~. so that the reaCtlon can ' proa2 + ~O -->2NaOH ; ceed. During the course of a • actinides : chemical reaction, energy must the Actinides (also called ~ be supplied to stretch and break Actinods) are the series of ele- I the bonds in the reactant molments from Thorium, Atomic ~ ecules~ and the energy required Number 90, to Lawrencium, : for . this. process is termed the Atomic"number 103. The Ac- ~ aCtlvatlon energy. New bonds tinides all have vwo outer s- i are then reformed during the electrons (i.e. having c 7s(2) ; course of a chemical reaction, electronic configuration). The .: to ~ake the products ofthe reLanthanoids and Actinides . ~ aCtlon. make up the f-block. I • acylaction reaction • activation energy ; this reaction involves the introthe activation energy of a ; ~uctionofanacylgroup (RCO) chemical reaction is the mini- : mto a compound. mum energy required to initiate ~ Method. An Alkyl halide is rethe chemical reaction (i.e. cause ; acted .Wl~ an alcohol or a carthe chemical reaction to take : .boxylic aad anhydride e.g. place). It is the energy required ~ RCOCI + ~OH == = > I
RCOO~+HCI
; The introduction of an acetyl : group (CH3CO-) is Acetyla• :I ~lOn, a process used for protectI mg -OH groups in Organic : synthesis. I
: I : I . ;
• addition polymerisation addition polymerisation is the ... Jommg together oftwo or more simple molecules, called Mono-
IIlIIIdition mu:tions I airpollution
9
mers, to form a new compound ~ bond or the triple bond) of of the same empirical formula, ; another molecule (called the ~ substrate) to give a single : product, formed by the com~ bination of both reacting mol; ecules. For example, bromine ... : adds across the double bond l:: .. ~ of ethene (i.e. Ethylene) in an \'" -~;fa «J~ - * I addition reaction to form .. . ; dibromoethane. called a polymer which has a : CH =CH +Br==> I 2 2 very high molecular weight. : H 2BrCH2Br The addition polymerisation ~ - adsorption process can only occur when the monomer molecule is un- ~ adsorption is the surface phesaturated (i.e. contain double ; nomenon involving the attachbonds or triple bonds). Thus, : ment of a gas or liquid to the addition polymerisation is char- ~ surface of a solid. This surface acteristic ofethene and the other I property of solids is exploited ~ in Chromatography for the ethenes. : The polymers formed byaddi- I separation of nllxtures. tion polymerisation are thermo- : - air pollution plastic . These include ~ air pollution is the degradaPolythene, Polypropylene and I tion of the quality of the atPolystyrene. . ~ mosphere by chemical and . : particulate contamination. - addition reactions addition reactions normally ~ Acid Rain is a manifestation occur with unsaturated com- ; of the deterioration of the pounds and involve the addi- ~ quality of the atmosphere as tion of one molecule (called : a result of the combustion of the reactant) across the unsat- I fossil fuels. urated bond (i.e. the double I ~
. - ::;..--
Inorgllnic Chemistry
;;;;;;;;;;;~~~~~~~~~~~~~~~= II
- Albert einstein ~ Studies at Princeton, New JerEinstein contributed more than i sey from 1933AD. any other scientistto the mod- :I He was awarded the Nobel em vision of physical reality. His : Prize in physics in 1921A.D. for ~ applying Planck's Quantum i Theory to the explanation ofthe : photoelectric emission of elecI . trons. I
: - alchemy ~ alchemy was the so-called black ; art of renaissance Europe which : sought ways of converting ev~ eryday substances into gold.
'al d . speC! an general theones of I . relativity are still regarded as : - alcohols, absolute the most satisfactory model of ~ absolute Alcohol, C 2H sOH, the large-scale universe that we ; (i.e. 100% Ethanol) is pure anhave. : hydrous ethanol. Absolute alcoA German born Swiss-Ameri- ~ hoI has a boiling point of 78.3 can, Albert Einstein (1879- ~ dc. It is a clear colourless liq1955) is the author of the; uid with a pleasant smell. It is Theory of Relativity. : completely miscible with water He worked in the Berne patent ~ and organic solvents and is very office in Switzerland, where in I hydroscopic. his spare time he developed a ~ Absolute Alcohol is obtained number of theories, which he : from 95% Alcohol by using a published in 1905AD. These ~ ternary azeotrope (i.e. by disincluded a mathematical expla- ; tillation using a three componation of the Special Theory of : nent Azeotrope). Relativity, the Photoelectric Ef- ~ A mixture of7.5% Water (boilfect and Brownian Movement. ~ ing point 100 °C), 18.5% EthaHe was professor of matbemat- ; nol (boiling point 78.3 °C); and ics at the Institute of Advanced :. 74% Benzene (boiling point 80 I
II = = = = = = = = = = InDf1/II1f.ic CbenIimy
°C), forms a ternary azeotrope (boiling point 64.9 °C), which is a minimum-boiling mixture. Benzene and Ethanol form a binary azeotrope (boiling point 68.2 °C). Thus, when a mixture of 95% ethanol and benzene is distilled, theaboveternaryazeotropedistills first, followed by the binary · . azeotrope, and the final fracoon (b.. 78.300C) is absolute alcop hol. _ alcohols aliphatic
~ Methanol and ethanol are the ; first two members of the series. : Compounds of this type with 1 : one hydroxyl group per mol~ ecule are known as monohydric ; alcohols. : _ alcohols dihydric ~ h 1 1 I CH H ; ~~y~~e. ~yco,. 2 IS : dih.&.""2d . 'al he f iostdunpo~t 1 Y' nc co 0 l an approXl. 5 . ; mately 7 % o~that produced IS 'j used as an ann-freeze agent.
°
1
~ - alicyclic compounds : alicyclic compounds are ring
the aliphatic alcohols are a series of homologous series or- ~ comdfpoun::t .c~n~g single ganic compounds containing ~ : : : : e;r n to c: one or more hydroxyl groups [_; n n . .C'f c co~un OH] attached to an Alkyl Radi- : do not contaIn ~e conjugated cal. 1 double bonds which are characThe aliphatic alcohols can be ~ teristic of aromatic compounds. regarded as derivatives of al"" kanes in which one or more hydrogen atoms have been re- 1 '2.<~-_~U_ ._", placed by hydroxyl groups [- I , OH] . The general formula of : saturated aliphatic alcohols is ~ "'" CnH2n+lOH, where n=1,2,3, ~ _ aliphatic compound ~tc. The sa~ated carbon chain ; an aliphatic compound is an orIS often deslgnated by the sym- : ganic compound which consists bol R, so that R?H can repre- ~ of carbon and hydrogen in a sent any alcohol m the homolo- ~ structure which consists ofopen gous senes.
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Ino'1ltlni& Chemistry
I
================ II
12
IIlItmes IIIlItma
unbtanched chains of carbon ~ atoms, open branched chains ; of carbon atoms, or closed : - bo . I · f car chaUlO natoms (I.e. ring : or ~.c structures where the I. co~ undshavechemicalprop-; emes that resemble those in the : alkanes, alkenes, or alkynes). ~ • alkenes I
II
between internal carbon atoms in the chain. Ethene C H 24
~=C~
Propene C 3H 6
CH3CH=C~
Butene C4Hg C~~CH=C~ Pentene CSHIO
the alkenes, (i.e. the olefms), ~ ~~~~CH=C~ are the second homologous se-: eptene C6 H12 des of hydrocarbons, where ~ C~~~~CH=C~ there is at least one double- I Hexene C~14 . . CH CT-f rJ..T bond between the carbon atoms ; 3'" ~....,... ~ in the molecules. : ~CH22CH=~ ~ Octene CSH16 AA
l
AA
B B +
'n' BRB
;C~~~~~~
:CH=~ ~ Nonene C;IlS
;~~~~~~~ The alkenes are said to be un- ~ CH=C~ saturated because of the existence of a multiple bond in the molecule. The general structure of the alkene series of hydrocarbons is C nH 2n . The first member of the ethene series is ethene, (previously called ethylene). In the case of higher members of the alkene series the double bond may be be~ tween the terminal carbon atoms -of the chain, or may be
: Decene CIO~O
~ ~~~~~~~~
; CH = CH 2 : Ethene, propene and butene ~ are planar compounds. The I first bond on the unsaturated ~ carbon atoms are Sp2 hybrids, : and these bonds are arranged ~ as far apart in space as pos; sible (i.e. at 120 degree in the : same plane). These are s ~ bonds (sigma bonds) and are I
11--==========
I'""1JMIie Chemistry
13
1/ IIlltyl rtUlietU I IIlloy
formed by the end -on overlap of Sp2 hydride orbitals of the carbon atoms. The second bond that makes up the double bond of the unsaturated carbon atoms in alkenes is a p-bond (pi-bond), formed by the side-on overlap of the p-orbitals of the carbon atoms. p-bond (pi-bonds) are much more reactive than the s bonds (sigma bonds). _ alkyl radical an alkyl group or an alkyl radical, is structurally similar to an alkane group, where a hydrogen atom is missing. Alkyl radicals are named by replacing the ending "-ane" from the name of the alkane, with the "-yl" smflx. _ allotrope an allotrope of an element is one of the forms in which the element can exist. For example, carbon can exist in several different forms, including graphite and diamond (which are pure forms of carbon that have different crystal structures) and charcoal, coke and lampblack (which are impure forms of carlnorglmic Chemistry
~
bon that are amorphous). Sulr phur can exist as five different ~ allotropes. :I - alloy : an alloy is a solid solution of ~ one metal in another. It is an ; example of a mixture, as no ~ chemical bondin~ exists be: tween the constItuent ele~ ments in the alloy. Common ; examples of alloys include : Brass (an alloy of copper and ~. zinc, and sometimes other ~ metals, known since Roman ; Times and widely used in in: dustry, for ornament and ~ decoration), Bronze (an alloy I of copper and Tin used for ~ tools, weapons, machine parts : and marine hardware), Stain~ less steel (an alloy of iron, ; chromium and nickel used for : cutlery and industrial compo~ nents where corrosion resis~ tance is required), Duralium ; (an alloy of aluminium, cop: per, magnesium, manganese ~ and silicon used in aircraft conI struction) and Solder (an al~· loy of lead and tin used in : making electrical connec~ tions).
================= II
14
• alloys of iron ~ a nwnber of steels are the im- "' portant alloys of iron, which : ~ include, Steel ~ Stainless Steel ; Chromium Steel ; Tungsten Steel ( :
• alpha-particles ~ an alpha-particles is the charged ~ particle emitted from the; nucleus during its spontaneous : decay. It haves the same struc- ~ ture as the nucleus of a heliwn , atom, consisting oftwo Protons : and two Neutrons. ~ ~ Alpha Particle Radiation
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_............ ,......• amides \ amides are organic compounds containing the amide functional group (i.e. -C=O.NH -). 2 Amides can be regarded as either a carboxylic acid derivatives in which the hydroxyl group, -OR, of the carboxyl acid group is replaced by an
~
,
~
: ~
~ ; :
~ ; :
~ ~
amino functional group, -NH2, or as an ammonia derivatives in which a hydrogen atom is replaced by an acyl functional group, -c=oAmides are volatile solids. • amines amines are organic compounds containing carbon, hydrogen and nitrogen which are derived from ammonia by replacing one or more of the hydrogen ato~ by a1ky~ alken~ a1kyny~ or arylgroups. Thus, the amine fimctional group, ,-~, is contained within the molecule. Amines are classified as Primary Amines, R-~, where one of the hydrogen atoms of ammonia is replaced by an alkyl, alkenyl, alkyny~ or aryl functional group, Secondary Amines, R-~, where two of the hydrogen atoms of ammonia are replaced by an alkyl, ~enyl, alkynyl, or aryl ~c tlO~al groups, or TertIary Ammes, R- N~~', where all three of~e hydrogen atoms of ammoma are replaced by an alkyl,. alkenyl, alkynyl, or aryl funcnonal group.
II amount ofa S'Ubstanee I atudysis
15 .~~~~~~~~
There are significant differ- ~ H 20 + NH3 <==> NH4 (+) ences in the reactivities of these I + OH(-) H 20 + HCI ~ <==> H30++ CI(-) ammes . • amount of a substance the amount of a substance is measured in moles. One mole is the quantity· of the substance (i.e. the weight of the substance in grams) that is present in numerically the same as its molecular weight. • amphoteric oxides amphoteric oxides are the oxides of weakly electropositive metals. Thus, the oxides of aluminium oxide, zinc oxide, and tin oxide are amphoteric o,q,des. These amphoteric oxides react as basic oxides with acids and as acidic oxides with bases. Aluminium oxide reacts with acids ~03 + 6 HCI = = > 2 AlCl 3 + 3 ~O Aluminium oxide reacts with bases Al 03 + 2 NaOH + H 0 2 2 = = > 2 NaAl(OH)4 Water is also an amphotercic oxide
1m1f1J."" Cbemistry
~
: ~ I
~
: ~
~
• amphoteric substance an amphoteric substance is one which has both acidic and basic properties and which can behave as a weak base or a weak acid underdifferentexperimental conditions. • analysis
analysis involves the determina~ tion of the composition of a : sample. ~ Qualitative Analysis involves I determining the nature of a ; pure unknown compound or : the compounds present in a ~ mixture. Quantitative AnalyI sis involves measuring the ~ proportions of known compo: nents in a mixture, and the ~ chemical techniques include ; volumetric analysis and gravi: metric analysis. Instrumental ~ Analysis include several physi~ cal tech~iques including spec; troscopic techniques, mass ~ spectrometry, polarography, : nuclear magnetic resonance, I etc. I
================
It
16
• anion an anion is the ion which is attracted to the anode. Thus, it is the negatively charged ion.
tmion
IIIIJ1IeOUS solutUms /I
I
• anion hydrolysis anion hydrolysis involves the reaction of the anion of a salt ~ with water to give excess hy- I droxyl ions in solution. • anode an anode is the positive electrode in electrolysis experiments, and it is at this electrode that the ions lose electrons. Thus, oxidation reactions occurs at the anode.
anti-MarkownikofI rule the anti-Markownikotf rule specifies the orientation, in the
I •
I · 1) B,H.
I 2) H,O,INIIOH
J-"..thylcycloptnUItI
I presence of free radicals, in • anode reactions which an asymmetric molecule anode reactions are the chemi- adds across the double bond of cal reactions that occur at the I an alkene in an addition reacanode of an electrochemical I tion. The orientation of the adceil, involve the negative ions dition across the multiple bond in solution which migrate to in the presence of free radicals the anode, where they lose an I is opposite to that specified for electron and are deposited as I ionic reactions in the neutral atoms. Anode reac- MarkownikoffRule. tions are oxidation reactions, ~ I . . c. f ·I . aqueous so. utions th as they mvolve the tranSler 0 an electron from the nega - : aq~eous soluttons ar~ ose so. 1 h d. luttons where water IS the solnve y c arge Ion. vent. An aqueous solution found in an equation describing
II ================ lnorgllnic Cbemistry
17
111J7meS IlJromatic compounds
*==========~=== a chemical reaction is denoted ~ oxidation state (i.e. + 1 oxida-
by the state symbol, (aq).
; tion state) , Ag+ .
• arenes ; • aromatic compounds the arenes are a homologous aromatic compoW1ds are ring series of aromatic hydrocar- compoW1ds with a benzenoid bons, which have a ring struc- I structure (i.e. have a ring structure of six carbon atoms, with I ture of six carbon atoms, with alternating single and double alternating single and double bonds. This closed ring struc- bonds),orthose resembling benture has a very high stability and I zene in chemical behaviour. these aromatic compoW1ds W1- I dergo substimtion reactions in order to preserve the configuration of the ring structure. • argentic compounds argentic compoW1ds are ionic compounds of silver in its higher oxidation state (i.e. + 2. oxidation state), Ag++.
--
I
• argentometric titrations argentometric titrations are I those in which an aqueous soI lution of silver nitrate is used ~ Although aromatic comto quantitatively precipitate a pounds are unsaturated, they silver halide (e.g. silver chloride, ~ do not readily undergo addisilver bromide) or other in; tion reactions, instead undersoluble silver salt (e.g. silver going electrophilic subs timthiocyanate) from solution. tion to preserve the stability • argentous compounds I of the aromatic ring. The simargentous compoW1ds are ionic I plest aromatic compound is compoW1ds of silver in its lower benzene, C6 H 6 • Inorganic Chemistry
==========~======__ II
",,18===========47
ricst4biJilY
14tmospheriepollution 1/
• aromatic stability I vides hydroxyl ions as a result aromatic stability is the resis- I ofdissociation and ionisation in tance of aromatic compounds aqueous solution as being to undergo addition reactions bases. on the ring structure which ~ • Arrhenius concept of would destroy the aromatic I neutralisation character (i.e. alternating single I the Arrhenius concept of and double bonds) of the aro- neutralisation involves the reacmatic ring. Aromatic com- I tion in which a hydrogen ion pounds readily undergo substi- ~ . and a hydroxide ion combine to tution reactions that preserve form water. the aromatic structure of the I ring. Aromatic stability is ex- ~ • atmospheric carbon dioxplained by resonance. ide I atmospheric carbon dioxide re• Arrhenius concept of acids I sults from the combustion of the Arrhenius concept of acids, fossil fuels, and it is an imporgave the fIrst understanding of ~ tant contributor to the greenthe true nature of acids in aque- ; house effect. ous solution. Arrhenius proposed that acids are substances which give rise to the hydrogen I ions in solution and that bases are substances that give rise to hydroxyl ions in solution. It is I the ionisation of the"acid which I gives rise to these hydrogen ions and thus also gives rise to the acidic properties. I • atmospheric pollution ~S04~=> H+ + HS04 I atmospheric pollution is caused • Arrhenius concept of bases by the emission of substances the Arrhenius concept of bases which are not natural constituregard substance which pro- I ents of the air, including soot,
II ================= Inot;!JlJnic Chemistry
II
baclt-tit'rtltUms I btdanced chemical e;""tions===========19
smoke, carbon monoxide, hy- ~ • back-titrations drocarbons, lead compounds, I back-titrations may be used in carbon dioxide, chlorofluoro- ~ volumetric analysis where direct carbons, sulphur dioxide, and : titrations cannot be used for technitrogen oxides . Soot and ~ nieal reasons. For example, when smoke, which are particulates ; a compound is not soluble in released during the combustion : water, or where it contains imof solid fuels, can be controlled ~ purities which interfere with diby using smokeless solid fuels. I reet titration, an excess of the tiThe smoke emitted from die- ~ trant may be added, and the exsel engines can be controlled by : cess then detennined by titration the use of properly adjusted fuel ~ (i.e. by back titration). injectors. Levels of sulphur di- ; . • balanced chemical equaoxide can be reduced by using . tions low sulphur fuels. The quantity of lead compounds which are ~ balanced chemical equations emitted from petrol engines : describe the chemical changes has been reduced significantly ~ which occur during the course since the introduction of lead_ ; ofa chemical reaction, and idenfree petrol. The quantity of car- : tifies reactants and products, bon monoxide and ofhydrocar- ~ Gives the correct composition bons which are emitted from ~ of each reaetant and product, petrol engines can be reduced; Gives relative numbers of atbyusingproperlyadjustingand : oms, ions and molecules intuning the engines of cars and ~ volved, and by fitting catalytic converters. ~ Gives relative weights of subInternational agreements has ; stances. lead to the reduction of the : For example, the following quantities of chlorofluorocar- ~ equation indicates that two bons which can be manufac- ; moles of hydrogen react with mred. Alternative new com- : one mole ofoxygen to form two pounds are being developed to ~ moles of water. ~ 2H2 + 02 ==> 2 H 20 replace the CFes.
Inorganic Chemistry
================= II
20
base I beta-particf
I
=========* • base
a base is a substance, which reacts with an acid to form salt and water only. Arrhenius in his researches in to the behaviour of electrolytes in solution proposed that a base is a substance which provides hydroxide ions in aqueous solution as a result of dissociation and ionisation. Later, Lewis introduced the idea that acids and bases had a reciprocal relationship and he introduced the concept of Lewis conjugate acid/base pairs. A Lewis Acid (conjugate) is an electron pair acceptor and a Lewis Base (conjugate) is an electron pair donor. NH3(Lewis Base) + H3 0 +(Lewis Acid) = = > NH/ (Lewis Acid) + H 20 (Lewis Base) , In particular, water and the Hydrated Proton, H 30 +, are a conjugate acid-base pair, as the hydrated proton is able to donate a proton to water and water is able to receive the proton. H+(Lewis Base) + H 20 ==> H30+(LewisAcid)
I
I
I
I
•
basic oxides
basic oxides are the oxides of metals (e.g. sodium oxide and copper oxide), and they react with water to form alkaline solutions.
I I
I I
I
I
I
I
I
I
Na 0 + H 0 = = > 2 NaOH 2 2 Basic oxides form salts and water on reaction with acids. Na 0 + 2HCI = = > 2 NaCI 2 + ~O CuO + 2HN0 ==> 3 CU(N0 )2 + H 0 3 2
Strongly basic oxides form compounds with water containing a metal combined direcdy to a hydroxyl group, they are therefore called hydroxides. The hydroxides of sodium and potassium are also called alkalis. ~O + H 0 = = > 2 KOH 2
• beta-particles I
I
a beta-particles is the charged particle emitted from the nucleus of an atom during its spontaneous decay.
II ================= Inorganic Chemistry
II
biochemical oxygen demand I Bohr mo;l""of=th"",c"",at"",um======="",2=1
_ biochemical oxygen demand biochemical oxygen demand, BOD, is the amount of oxygen taken up by microorganisms to decompose organic waste matter which is present in water. Biochemical oxygen demand is therefore used as an empirical measure of the amount of certain biologically de gradablle wastehtypes of organ.ic po lutant t at are present 10 water. Biochemical oxygen demand is calculated by keeping a sample of water containing a known amount of oxygen for five days at 20°C in the dark. The oxygen content is measured again after this time. A high biochemical oxygen demand indicates the presence of a large number of microorganisms, consuming large amounts of organic matter, which suggests a high level of pollution. There is an empirical relationship between the two determinants that describe pollution load in a sample (i.e. between biochemical oxygen demand and chemical oxygen demand).
Inorganic Chemistry
~
- biological oxidation biological oxidation involved the ~ mediation of biological species in : the Oxidation oforganic matter. ~ In general, biological oxidation ; proceeds by enzyme catalysis. I
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: - Bohr model of the atom ~ the Bohr model of the atom ; uses the particle theory of the : electron to explain the spectrum ~ of the hydrogen atom. ~ In 1913 AD, Neils Bohr used ; the particle theory of the elec: tron to explain the spectrum of ~ the hydrogen atom. I
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-
================= II
22
*
boiling point I Boltzmlmn ctmStRnt
II
Bohr postulated that the hydro- I of an electron fwm a higher gen atom consisted of a central I energy state to a lower energy positive nucleus round which an state involves emission of enelectron moved in atomic orbit : ergy in the form of radiation. and that an electron may only ~ Thus, the lines in the spectrum be found in one of a limited . of hydrogen are due to elecnumber of those orbits. trons falling from the excited The number of orbits was lim- I state (i.e. a higher energy ited, each corresponding to a I level) to the ground state (i.e. definite energy level, where the I the lower energy). Each line angular momentum, mvr, of : in the hydrogen spectrum is the electron in its path about the I ascribed to the transfer of an nucleus must always be equal to I electron from an orbit of a nh/2( (where n = 1, 2, 3 ... ) high n value to one of a lower Thus, n value. ~ _ boiling point mvr = nh/2 where m is the mass of the electron I the boiling point of a liquid is I the temperature at which the v is the velocity vapour pressure of the liquid is r is the radius of the orbit n is an integer called a Quan- equal to the atmospheric prestum Number used to I sure. The liquid changes from characterising the the liquid state to the gas state at its boiling point. orbit and h is Plank's constant. _ Boltzmann constant Bohr also postulated that as I the Boltzmann constant, k, long as an electron remains in I named after the Austrian physia given orbit it neither absorbs cist Ludwig Boltzmann (1844nor emits energy, and that 1906), is the ratio of the unimovement of an electron from I versal gas constant, R, to the a low energy state to a higher I Avogadro constant, No. The energy state involves absorp- Boltzmann constant, k, is as the tion of energy, and movement I gas constant per molecule.
/I ================= InD1lJllni& Chemistry
II
23
bomb calorimeter I bond energy
.==============~
k = R/Na, Na =1.380622 X 10-23 JKl
- bomb calorimeter a bomb calorimeter is an apparatus used for measuring heats of combustion. It consists of a strong container in which the sample is sealed with excess oxygen and ignited electrically. The heat of combustion at constant
-
~ two atoms involved in the bond ; and keeps the molecule intacv : as an entity. I
:I - bond energy : bond energy is the amount of ~ energy associated with a bond ; in a chemical compound.
~
;
---
:;g2. ~ .. " .1'V r O.238N11
~ For example, in methane the
--volume can be calculated from
; bond energy of the carbon to ~ hydrogen bond is one quarter : of the Enthalpy of the synthe~ sis process. ; CH4 (g) = = > C(g) + 4 H(g) : Bond energies can be calculated
~ I
from the standard enthalpy of formation ofthe compound and
the resulting rise in temperature of the calorimeter and its con- ; from the enthalpies of : atomisation of the elements. tents. ~ Energies calculated in this way - bond ; are called average bond energies a bond (i.e_ chemical bond) is : or bond energy terms. They I the attractive force between the : depend to some extent on the atoms in a molecule, which I molecule chosen; theC-Hbond keeps the molecule together. A ~ energy in methane will differ chemical bond between atoms : slighdy from that in ethane. The , involves the overlap of an ~ bond dissociation energy is a atofruc orbital frqm each of the ; different measurement, being Inorgllnic Chemistry
=========:;;;;;;;;;;======= I
"",24~~~~~~~~~=
*
bond pain I Boyle's itJw
II
the ~nergy require to break a ~ cannot be measured directly by partlcular bond. I experimental methods . • bond pairs bond pairs are the pairs of electrons involved in covalent bonds, or the unbonding lone pair of electrons which exist in a single sub-orbital of the central atom of a molecule . • bonding and structure in group VI oxides Silica, Si0 , forms a giant tet2 rahedral molecule which is bonded covalently. E~ery silicon atom is attached to four oxygen atoms, and every oxygen atom is common to two Si0 tetra4 hedral. Carbon, C, can form double bonds and Carbon Dioxide, CO , is an example of a 2 compound that exist as discrete molecules. However, since silicon cannot form double bonds Silicon Dioxide, Si0 2 , (i.e: Silica) only forms an infmite three-dimensional tetrahedral structure. • Born-Haber cycle the Born-Haber cycle is a cycle of reactions used to calculate the lattice energies ofionic crystalline solids. Lattice Energy
The Born-Haber Cycle Th,e Lattice energy can be calculated with Hess's law and the following steps: . ~.~(gJ.+.or .+.?,gl
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H
I ,(No)
i
...
E(~)j _r-I!I:19):,:c:;1(9L
... JN~(g1~.9l9L &H,·(ct,g
N~(i'-+ ~all~).
Mi,' (Na,g) Na 5
Lattice
+ %CI
energy
; • Boyle'S law ~ Boyl~'s L~w, is .the empi:ical : relatlonship, which states that ~ given a fIxed mass ofgas at con; ~tant temperature, its volume is : mversely proportional to its ~ pr~ssure. Boyle'S Law applies ~ to l~eal gases only. Real gases . deVIate considerable form this ~ ideal relatio~ship. It. i~ called ~ after the Insh phYSICISt and ; chemist Robert Boyle :
~
Fi.
. ;
Pz • ••
• •• ••• • •• I
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-
II ================ lnorgllnic Chemistry
II breathalysertest I BronstedLuwry th:;""Ofi"",at"",id"",S==========25
• breathalyser test ~ proton and a base as any subthe breathalyser Test is based on ; stance can accept a proton. The the colour change which occurs : relationship between an acid when the dichromate ions in a ~ and a base is represented by the glass tube through which the ~ following equation. person blows is reduced to ; HA <==> H(+) + A(-) chromate ion by the presence of : Acid Base alcohol in the breath. This is a ~ Here the acid, HA, and the test given to suspected drunken ; base, A(-), which differ from drivers, who are required to ~ one another bya proton, are deblow through a tube containing : scribed as a conjugate pair, (i.e. asolutionofaciWfied potassium ~ the Base, A(-), is said to be condichromate on an inert support. ; jugate base of the Acid, HA). When the ethanol, C 2H sOH, : It should be noted that the hyvapour is passed through the ~ drogen ion exist in aqueous sotube it is oxidised to carbon 1 lution as a hydrated proton, dioxid, and water. Correspond- ~ H3 O( +). ingly, the dichromate ions which : HCI + H 20 = = > I. Ao·d2 are ye11ow in colour, are reduced Base2 to chromate ions which are; H 20(+) + CI(-) green in colour. This results in : Acidl Base 1 1 the observed colour change : Bronsted and Lowry proposed from yellow to green when al- 1 that cohol is present in the exhaled ~ An Acid is a Proton Donor breath. : A Base is a Proton Acceptor ~ Thus, the ionisation ofsulphuric • Bronsted Lowry theory of ; acid satisfies this concept of an acids : acid, in that it donates a hydro• this theory of acids and bases 1 : gen Ion to water. which was proposed by ~ H S0 + H 20 ==> Bronsted and Lowry broadened ; H 20+ 4 + HS0 3 4 the Arrhenius concept of acids : Proton Donor Hydrated and bases by defining an acid as ~ Proton any substance which release a Inorganic Chemistry
================= II
Brownian nwvement I burette
26
/I
~=======*
Similarly, the hydroxyl ion is a base, as it can accept a proton from the hydrated proton. H30+ + HO- = = > 2 H 20 (Proton Acceptor) It should be noted that the hydrogen ion exist in aqueous solution as a hydrated proton. • Brownian movement brownian movement is the irregular zig-zag paths observed for the motion of pollen grains suspended in water, which strongly suggest that water molecules are moving about at random, and colliding with the grain pollens.
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microscope, the grains were seen to move in an erratic manner. They travelled along short straight paths, but the individual grains were rarely seen to collide with each other. The path of anyone grain can best be described as a zigzag line, with a straight path between each zig and zag. This zig-zag motion is called Brownian Movement. The irregular paths strongly suggest that the visible grains are pushed by invisible partides that are moving at random and which collided with the grains of pollen. If the water molecules are in motion, moving about at random, this would allow an explanation for the observations. This observation of Brownian Motion is one of the supporting pieces of evidence for the Atomic Theory and for the Kinetic theory of gases.
burette In 1828, Robert Brown ob- . a burette is a glass apparatus served the motion of pollen used in volumetric analysis. It grains which were suspended I is designed to deliver known in water. When these pollen I volumes of liquids during grains were viewed through a I •
II ================= Inorg{mic Chemistry
II
Celsius sCRle oftempemture I Celsius :=of""t""em""1'""em=tu""re======,,,,2=7
titration's, and consists of a thin glass graduated tube and a stopcock to control delivery of the liquid.
Burette
~ posit on the copper rod where ; they combine with electrons. : Cu++ + 2e- ==> Cu ~ The term half-cell is used to I describe the zinc rod in the soI lution of zinc ions. : Similarly, the copper rod in the ~ solution of copper ions is also ; called a half cell. ~ The zinc rod and the copper rod : are termed electrodes. If the ~ half-cells are left in isolation, a ; state of equilibrium is reached : and no further reaction takes ~ place. However, when the elecI trodes of each half-cell are ~ linked externally by means of a : wire and the cells are separated ~ by a porous partition, the elec; trons which would have col: lected previously on the zinc ~ electrode are now free to travel I along the external wire to the ~ copper electrode.
An electrical double layer is formed between the electrons in the rod and the ions in solution. The formation ofthis electrical double layer is accompanied by a potential difference ; • Celsius scale of temperabetween the rod and the soluture tion called electrode potential. If a copper rod is placed in a ~ the Celsius scale of tempera. contammg . . copper ions, . I ture, is the scale named after the soIunon the rod is found to be positively I: Swedish astronomer Andes charged with respect to the so- Celsius, where the temperature lution. In this instance metal I range between the melting ions leave the solution and de- I point at standard pressure of ice and the boiling point of water Inorganic Chemistry
====11
~2~8~~~~~~~~~~~c~~t~~~~~~~nd~C~~~~~~I~Ch~a~in~r.~~~t~ion= /I ;q '~ , 2120F 1: ___ WII:Ic:r_[ - IOO"C I boils ; , ~
t·
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98.6°F -\ 320F -1 ,
I
(i.e. cement) which hardens underwater.
I
.,ceramics ceramics are inorganic materials, such as pottery, enamels and refractories.
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5O"C ' , ,,- 37"C
-
_
Water_y - O"C freeze.< ,
'''''F -: -..., :
,,-4O"C --5O"C
-IOS0F-' __ DIy,ce ___ -_780C (solid CO2) ' _ -IOO'C
Liquid air
-312°F,
Aboiolute
-459°F- - - zero
'--15O"C __ 191°C • --2OO"C
I
, --25O"C - _273°C I
Fahrcoheit
Celsius (Centigrade)
I
has been divided into 100 degrees. The melting point of ice is taken as zero degrees and written as DoC. The boiling point of water is therefore taken as 100 degrees and written as 100°C.
I
I
• chain a chain is a linear combination of the same type of atom in a molecule. In straight chain molecules, the atoms are arranged in a line, with each atom in the chain linked to one preceding atom and one succeeding atom of the same type. In branched chain molecules, groups are attached to a central straight chain, and the group is called a side chain. A closed chain molecule is a chain where the atoms are linked in a ring structure; otherwise, the molecule has an open chain molecule.
• cement (portland cement) I portland cement, so called be- I cause after setting it resembles • chain reaction Portland stone, is made by heat- a chain reaction is a multi-step ing a mixture oflimestone and I sequence of chemical reactions clay, which is then ground to a I in which a product of the first fme powder. Limestone con- I step is used as a reagent in the taining more than 5 per cent of : second step, and a product of clay on burning forms a lime, i the second step is used as a rewhich gives a hydraulic mortar I agent in the third step, etc.. In
II ================;;;;; Inorganic Chemistry
II
chaos I chaos
29
*================ general, chain reactions are free ~ a molecule of methane to proradical reactions. ; duce a methyl free radical and ~ a molecule of hydrogen bro, . . .u 'd :...~U ~ ~:*: CH = = > CH * + HBr 'x,
i e;.. ~.~U:
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(2)
~ The methyl radical then at-
k
-:.,aa
b'
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: tac s a romme mo ecu e to , . ~u • • ~x' ~:':U ~ produce a molecule of methyl ~.. ". .u I bromide and to regenerate a bromine free radical, which For example, the reaction of ~ proceeds to react as in step (2). bromine with methane in the ~ CH3)(- + Br2 = = > CH3Br + presence of light is an example; Br* (3) of a chain reaction. The mecha- : The Termination of the Reacnism by which the reaction pro- ~ tion ceeds is as follows. ~ is the final step and results The first step is called the lni- ; when these steps can are tiation of the reaction. : stopped by the chance recomThe absorption of light breaks ~ bination of free radicals as in the covalent bond holding to- ~ (4). gether the bromine atoms to- ; Br* + CH * = = > CH Br (4) 3 4 gether in the bromine molecule , or and produces free bromine at- ~ Br* + Br* = = > Br oms (i.e. bromine free radicals, ; or 2 Br*). ; CH * + CH * ==> C H Br2==>Br*+Br*(1) 3 3 26 The Propagation of the Reac- ; • chaos tion involves repeating steps ~ chaos is the widely diverse (2) and (3), where the bro- : rangeofbehaviourwhichnonmine free radical then re- ~ linear dynamic systems exmoves a hydrogen atom from ; hibit under different initial :I conditions.
.,.U
Inorganic Chemistry
:
================= II
Charlc>s law I chemical change "
30
=================* • Charle's law Charle's Law is the empirical relationship, which states that which states that for an ideal gas at constant pressure, its volume is proportional to its absolute temperature. This relationship applies to ideal gases only. Real gases deviate considerable form this ideal relationship .
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It is called after Jacques Alexandre Cesar Charles • chemical bonds chemical bonds are the forces that hold atoms !ogether in a molecule are called chemical bonds. A Chemical Bond is the attractive force between two atoms
I
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in a molecule. These bonds keep the molecule intact as an entity. In 1916AD, the two kinds of chemical bonds which were known were described as the Ionic Bond by Walter Kossel (Germany) and the Covalent Bond by G.N.Lewis (University of California). These ionic and covalent bonds arise from the tendency of atoms to attain a stable configuration ofelectrons for each atom in a molecule, by either the transfer or the sharing of electrons between atoms. Because a molecule consists of at least two atoms with positively charges nuclei and negatively electronic clouds about these atoms, there are electrostatic interactions between the various particles of the atoms in the molecule. • chemical change a chemical change is a process which results in the production of one or more new materials. The system within which the process takes place is called a chemical system. A chemical change is also known as a
II ================== lnorgRnic Chemistry
II
chemical equilibrium I chromatoBrap;
chemical reaction, where one substance is converted into one or more different substances. When sodium and chlorine react to produce sodium chloride, a chemical reaction has taken place.
31
~ Many of the initial letters of the ; elements; others have a second : letter where there is more than ~ one starting with the small let~ ter. Example include . Hydrogen H Helium He Lithium Li Sodium Na
• chemical equilibrium chemical equilibrium is a state of dynamic equilibrium is set I • chloro-organics up when the rate of the forward ; the simplest type of chloro-orreaction is equal to the rate of : ganic compounds are the the back reaction. ~ chloroaikanes, which fmd ex; tensive use as solvents in indus• chemical formula : try. a chemical formula shows the I : Chloromethane, CH3Cl number and types of atoms that ~ Dichloromethane, ~C~, (i.e. are present in a molecule. ; Methylene Chloride) • chemical oxygen demand : Chloroform, CHCl3 the chemical oxygen demand is ~ Carbon Tetrachloride, CCl4 the quantity ofoxygen required I 1,2-Di:hkxu1ban; ~~a to destructively oxidise the or- ~ l,l-Dichloroethane, CH~~ ganic matter in a sample. It is ~ • chromatography expressed in mg COD per litre. : chromatography is a tech• chemical symbol ~ nique for analysing or separata chemical symbol is assigned ; ing mixtures of gases, liquids, to every element, which repre- ~ or dissolved substances. In sents one atom (occasionally, general, all types of chromaone mole) of that element. The I tography involve two distinct symbols of the elements which I phases, (a) a stationary phase were known in earlier days were (i.e. the adsorbent material) derived from Latin names. ~ and (b) moving phase (i.e. the
Inorg/lnic Chemistry
================= II
column c~togmphy ,column chrrmllz;togmphy
32
e!uting solvent). The se~~ra- ~ tion depends on competition I for molecules of sample be- : tween the moving phase and ~ the stationary phase. ; 1dsorptio~ Chromatography ~ IS a technique for the separation : and analysis of mixtures of ~ gases,liquids,ordissolvedsub- ; stances. In the case of liquid:
. SoMnt Front Separated {
Dyes
Ink SpOil;
adsorption chromatography, a ve.rtical glass robe is packed WIth an adsorbing material, (e.g. Alumina, ~03' or Silica Ge~ Si0 ), the sample is poured 2 onto the top of the column and then continuously transported downthroughthecolumnwith a solvent, in a process called Elution. Different components of the sample are adsorbed to different extents and move down the column at different rates. The usual method is to collect the
II
liquid (i.e. the eluatent) in fractions, as it passes out from the column.
~ column chromatography IS the .oldest chromatographic t~chmque. The apparatus conSISts of a glass tube (approximately about 20mm ( 250mm) which has a glass frit ~ at the bottom of the tube and ; a stopcock. A thin layer of : coarse, clean sand is placed :I over the frit, and the chosen ~ adsorbent (usually alumina or ; silica) is then placed in the : tube as a slurry. ~~he sample under analysis ~ ~ I.e. the mixrore) is poured ~ mto ~e top of the column and ; c~ntInuousl~ washed through : ~Ith an eluting solvent. Frac~ tIons. are collected. As the mix; ture IS. passed through the col: ~,ItS components separate ~ mto zon~s of material (i.e. I bands) WIth a space between : each zone. A band represents ~ a frac~ion .of homogeneous ~ matenal (I.e. either a pure ; compound or a group of com~ pounds behaving as a single : compound on the adsorbent).
==========__ lnorgllnic Cbemistry
11 ......
II cis-mms isomerism
33
I coal
• cis-trans isomerism as well as the structural isom- I erism, which was illustrated in the alkane series, a new type of isomerism is possible in the I alkene series. There is not free I rotation about the carbon to carbon double bond, and therefore there are two dis- I tinct isomers possible, de- I pending on the layout of the ~ groups attached to the carbons : involved in the double bond. ~ The cis-isomer and the trans- ; isomers are distinct chemical.: compounds and they have dif- ~ ferent physical properties and ~ chemical properties. ; H
OH
)=N
H3C
ttans-isomer E-isomer
cis-isomer Z-isomer
The atoms of highest precedence on each end of the C=N bond are shown in red.
• coagulation coagulation is the process in which colloidal particles come together to form lager masses. Coagulation can be brought about by adding ions to neutralise the charges stabilizing the colloid. Ions with a high I
lnorglt.nic Chemistry
~ J~ ()
~
• ~
.A6_
~
o. o •
charge are particularly effective. Another example of ionic coagulation is in the formation of river deltas, which occurs when colloidal silt particles in rivers are coagulated by ions in sea water. Heating is another way of coagulating certain colloids.
; • coal : coal is a brown or black carbon~ aceous deposit derived from I the accumulation and alteration ; of ancient vegetation, which : originated largely in swamps or ~ other moist environments. As ; the vegetation decomposed it ~ formed layers of pea~, which : were subsequently burled. UnI der the increased pressure and I the resulting higher temperatures the peat was transformed into coal.
=================_11
34
c04lgl1S I combinetlgllS rm,
•
• coal gas coal gas is a gas produced by the destructive. distillation .of coal, and contams approXImately 50% hydrogen, 35% ~ethane and 8% carbon monoXide. ~he by products of the produCtlon of coal gas are coal tar and
~
• colo~~tric an~~sis c?lo~emc ~YSIS IS ~ quantltatlve analysIS of solutions by estimating ~e colour produced by the reactl?n ~f the sample under analys~ WI~ a ~eagent and companng It WIth the
~ • combined gas law
II
colours produced by known ; standard solutions. ~ • colour of halogens ~ the halogen molecules are all : coloured due to the absorption ~ ofvisible light. This absorption ; of light results in the excitation : of outer electrons to higher enCoke. ~ ergy levels. The energy required • coal tar ~ to bring about these electronic coal tar is a material obtained ; transitions follows the same from the destructive distillation : pattern as the ionisation potenofcoal in the production ofcoal ~ tial values for the elements. gas. The crude tar contains a ~ Thus, the energy required to large number of organic com- ; bring about such a transition in pounds (e.g. benzene, naphtha- : the smaller fluorine atom is lene, methylbenzene, etc.), ~ much larger than the energy which can be separated by frac- ~ required for the same transition ; for the larger iodine atom. tional distillation. 1_ : Fluorine absorbs the higher • cOl\.e I · I ligh and . . . . energyVlolet t ttansnuts coke IS ~ lID~ure fo~m of car- ; yellow light whilst the iodine bon, whIch IS obtamed a~ a : absorbs the lower energy yelbyproduct from the destruCtlve ~ low light and transmits violet distillation of coal. ~ light. ; : ~ ~ ; : I
the combined gas law is the mathematical relationship between the pressure, volume and temperature of a fIxed quantity ofan ideal gas, which states that the product of the pressure P. '
,
II """comb~ustwn~'~IC~ombu.stion~~·~of~ca~rb~on~.. and the volume, V, of one mole of gas is equal to the product of the gas constant, R, and the absolute temperature, T. pV = RT The combined gas law is derived from Boyle's Law and Charles's Law. • combustion combustion is the reaction of substances with oxygen, with the evolution of heat and light. The combustion of organic materials are often free radical chain reactions, which can usually be summarised as the oxidation ofcarbon content of the material to form its oxides and the oxidation of hydrogen to form water. The corrosion of metals is the result of the slow combustion of the metals with the oxygen in air. • combustion of calcium when heated in an iron deflagrating spoon, calcium burns brightly in oxygen forming calcium oxide, which turns moist red litmus blue. 2 Ca + O = = > 2 CaO 2 (Calcium Oxide)
lnot;!Janic Chemistry
35
~ CaO + H 0 = = > ; Ca(OH)2 2 ~ • combustion of carbon
~ a piece ofwood charcoal, which ~ is:n impure form of carbon, . w en strongly heated in a de; flagration spoon burns brightly, : and then placed in a gas jar con~ taining oxygen, burns even ~ more vigorously throwing off ; bright ~parks. ~ ~he .chief prod.uc: of the reac: tl~n lS carbon dioXlde, although I a little carbon monoxide is also ~ formed: : C + O 2 = = > CO2 ~ Carbon Dioxide ; 2C + 02 = = > CO ~ Carbon monoxi?e : When shaken Wlth water, the ~ Carbon Dioxide, CO2, dissolves ; forming a solution of the very : weak and unstable solution of ~ Carbonic Acid, H 2C03 , which I changes the blue colour of lit~ mus to a port-wine red colour : : CO2 + H 20 = = > H 2C03 I Carbon Carbonic Dioxide Acid ~ Ifanother jar ofcontaining Car: bon Dioxide, CO 2' from the I . combustion of carbon is shaken ; with lime water, this becomes : milky from the formation of a
================= II
36
combustion ofhydTOB; I combustion ofnon-metals in ~~
precipitate of Calcium Carbonate, CaC0 3 · Ca(OH)z + COz = = > CaC0 3 + H 20 • combustion of hydrogen when a jet of hydrogen gas that is prepared by the action of dilute sulphuric acid on zinc burns in a dry oxygen water is produced and it condenses as a dew on the inside walls of the jar. 2 Hz + Oz ==> 2HzO • combustion of iron
I
I
I
I I I I
I
II
combustion of magnesium when magnesium ribbon held in a crucible tongs is ignited in air and inserted into a jar of oxygen, it burns with a blinding white light, forming white solid magnesium oxide, which •
1~: ~~~r:~~ :~~~l~e~a~f~:
paper blue. • combustion of metals some metals, when heated strongly in oxygen, burn to form metal oxides. These oxides are the Basic Oxides. Other
when a spiral of iron wire tipped with a piece of burning wood, I is lowered into a gas jar con- metals do not burn readily in th· I oxygen, but react with it on . . t ammg oxygen gas, e Iron : . .d .. fif I. heatIng to form OX! es. 0 b urns b n·11·Iantly, glvmg bright sparks of the burning; • combustion of non-metals metal. Ferrosoferric oxide,: in oxygen Fe 30 4 , is formed in fused glob- the chemical characteristic of ules, which fall to the bottom I the non-metals is that their oxof the gas jar, on a layer ofsand. ides on reaction with water give It has no action on litmus. rise to acids. The acidic proper3 Fe + 2 Oz = = > Fe30 4 ties of the hydrolysis of these I oxides vary considerable, so that (Ferrosoferric Oxide) Ferrosoferric oxide may be re- the oxides of sulphur and phosgarded as a compound of fer- phorus give rise to strong acroUS oxide and ferric oxide and I ids, while the oxides of boron it is sometimes called a mixed I give rise to weak acids . ... oxide. Some non-metallic elements, FeO + FeZ0 3 ==> Fe 30 4 such as phosphorus, sulphur,
II ================= Inorganic Chemistry
II
combustion ofphosphorus I c~of=SO"",d."",·u"",m========3=7
and carbon, burn in oxygen to ~ 2 K + 02 = = > K20 2 form Acidic Oxides ; Potassium Peroxide : K + 02 = = > K0 2 - combustion of phospho- ~ Potassium Dioxide rus I When these substances are diswhen a piece of phosphorus on ~ solved in water, oxygen is an iron deflagrating spoon is : evolved and an alkaline solukindled by touching it with a ~ tions, containing potassium hyhot wire, and it is put into a gas ; droxide, which turn red litmus jar containing oxygen, it burns : blue is formed. in the oxygen with an exceed- I ·2KO + 4HO==> 4 ingly brilliant white flame, pro-· 2 2 2 ~ KOH + 02 ducing a whit~ cloud of ph?s- ; 4 K0 + 2~0 = = > 4 2 phorus pentOJade, P205' which : KOH + 3 settles in flocks on the inside of I 2 the dry jar. : - combustion of sodium P4 + 5°2 = = > 2 P205 ~ when sodium is heated in an When water is poured into the ~ iron deflagrating spoon until it jar the oxide dissolves and phos- ; ignites and then lowered in dry phoric acid is formed, which : jars of oxygen, it burns with changes the colour of blue lit- ~ bright yellow flame forming mus solution to red: I orange-yellow solid higher oxP20 S + 3~0 ==> 2~P04 ~ ides (e.g. sodium peroxide, _ combustion of potassium : Na20 2)· ~ 2Na + 02 ==> Na20 2 when potassium is heated in an ; When this substance is disiron deflagrating spoon until it : solved in water, oxygen is ignites and then lowered in dry ~ evolved and an alkaline solujars of oxygen, it burns with I tions, containing sodium hybright lilac flame forming or~ droxide, which turn red litmus ange-yellow solid higher oxides : blue is formed. (e.g. potassium peroxide, I. 2NaO 2 2 +2HO==> 2 ~02' and potassium dioxide, ; 4 NaOH + 02 K0 2 )·
°
Inorganic Chemistry
================= II
combustion ofsulphur I compound
38
II
~~====~=====*~============
• combustion of sulphur ~ C 1oH 9 naphthyl when a small amount of sul- ; Alkenylgroups vinyl phur is kindled on a deflagrat- : C2H 3 ing spoon, it burns with a C3H S allyl bright blue flame when intro- I • component duced into a gas jar contain- I a component is a distinct chemiing oxygen. A gas, sulphur di- ~ cal species in a mixture. rfthere oxide is the main product of : are no chemical reactions bethe combustion. However, a I tween the components in a mixlittle sulphur trioxide is also I ture, the number of compoformed, which makes the gas ~ nents is the number of distinct slightly doudy. : chemical species. S + - 2 ==> S02 :I • compound 2 S + 3 02 = = > 2 S03 I When shaken with water, the a compound is a substance Products of combustion dis- I composed of two or more elsolve, forming an acidic solu- ements that are bound totion which turns litmus red. gether by chemical bonds. A S02 + H 20 = = > H 2S03 compound cannot be broken SO + H = = > H SO I down into its individual ele3 2 2 4 ments of which it is composed • common group by physical means. However, I common groups which are de- a compound can be broken rived from hydrocarbons in- down to the elements of which dude: it is composed by chemical Alkylgroups means. CH3 methyl I Compounds Elements C2H S ethyl Calcium chloride H C3 7 propyl Calcium, Chlorine C4~ butyl I Calcium oxide C~29 nonyl I Calcium, Oxygen Aromaticgroups Sodium chloride C6 H S phenyl Sodium, Chlorine
°
°
" =============== I~anic Chemistry
I compound ions I condensation polymerisation
I,
39
*~==============
~ are incapable of independent Hydrogen oxide ; existence. They have an overHydrogen, Oxygen Iron oxide ~ all charge. Examples include Iron, Oxygen : the carbonate ion, C0 3 " , niJust as every element has its ~ trate ion, N0 3", ammonium own symbol, every compound ; ion, NH4 ++, etc. has its own formula. The for; • concentration mula identifies the elements present in the compOlmd and ~ conc~ntration is the quantity the number of atoms of each: of dissolved substance per kind that are in a molecule of ~ unit quantity of solvent in a ~ s?lut~on. The mass concentrathe compound. As all compounds are made ; tl0? IS the mass of solute per from elements so the elements : umt volume of solvent. The , I molal concentration is the are the building blocks of com- . . pounds. When a compound is ~ amount of substance per umt formed by the combination of ; mass of solvent. elements, this reaction is called : - condensation ~ condensation is the change of a a sy~thesis reaction. Unhke the elements, com- ~ vapour or gas into a liquid. The p.ounds can be spli~ up into ; change ofphase is accompanied SImpler substances (1.e. the el- : by the evolution of heat. . ements of which they are com- ~ posed). The splitting up of ; • condens~t1~n compounds into simpler sub- ~ ~olymerlSatiOn stances is called decomposi- : thIS may be defmed as the proI cess in which the monomer tion. ~ molecules of different com. • compoun~ lOns : pounds combine with the loss compound ~ons are gr?ups of ~ of some simple molecules, like atoms whIch remalll un- ; water, or HC!. changed through a series of : chemical reactions, but which I
Inorganic Chemistry
================= II
""40""""""""""""""""""""""""""""""""""""""""""""""""""",, ;ondensation ~tion I configuration I
Monomers of nylon
I
o
0
1/
tube and is cooled by the water flowing around the condenser's outer jacket.
II " H-O -C~~~,~j-C-O-H hexanedioic acid
H
I
H
I
H -N -:
This process can produce both thermoplastics and thermosetting plastics. e.g. Polyesters and nylon are formed by this process. • condensation reaction condensation reaction are those chemical reactions in which two molecules combine to form a larger molecule with elimination of a small molecule , typically water, during the course of the reaction. • condenser a condenser, (i.e. a Liebig Condenser) consists of a straight glass tube enclosed in a glass jacket through which water is passed. The condenser speeds the cooling and condensing process, when vapour passes through the condenser's centre
I
\ DlsnLLED
WATER
• conductimetric titration a coductimetric titration is one I in which the electrical conductivity of the reaction mixture is continuously monitored as lone reactant is added. The I equivalence point (i.e. the :I end-point of the titration) is . . : the pomt at whIch the conduc~ tivity undergoes a sudden ; change . configuration two defInitions are associated with the term, confIguration. ConfIguration is the arrangement of atoms or groups of atoms in a molecule, or ConfIguration is the arrangement of electrons about the nucleus of an atom.
I •
I I
I
II ================_ Inorgllnu Chemistry
II
conical flask
I contact process
41
*================
~ • consolute temperature • conical flask a conical flask is used for I consolute temperature is a temtitration's to facilitate the return ~ perature at which two-partially ofliquid splashed onto the walls : miscible liquids become fully of the flask to the body of the ~ miscible as the temperature is liquid at the bottom ofthe flask. ; increased.
contact process ~ the contact process is used for : manufacturing sulphuric acid ~ and fuming sulphuric acid from ; sulphur dioxide, which is made : by burning sulphur or byroast~ ing sulphide ores and oxygen I (in the form of air) which com~ bine to form sulphur trioxide in : the presence of a Catalyst. The ~ reaction is exothermic and the ; conditions are controlled to : keep the temperature at 450°C. ~ The catalyst used is valadium ~ (V) oxide (V20 S ) . The sulphur ; trioxide is dissolved in sulphuric : acid to form fuming sulphuric ~ acid, this called oleum. ; S(S)+02(g)==>S02(g) • 2S0 ( ) ; 2 g + 2 g = = > : 2S03 (g) S03(g)+ ~S04(l) ~ ==> ~S207 (l) Oleum : This Oleum is then diluted with I . . water lllto concentrated ~ sulphuric acid. I •
• conjugated bonds conjugated bonds describe the alternating pattern of double and single bonds, or triple bonds and single bonds, in a molecule. In such molecules, there is some delocalisation of electrons into the pi orbitals of the carbon atoms linked by the single bond. Conjugated Double Bonds
II.B.ii.·17
• Two of thHe structuftt rontain I"lmjug.1h·J double
bonds - p.utiruJarty stable )
,
, ", __
•
. '~, .
10 II
"
H
..
° ()
;
"
H
~/.,.; ' - \~"~" U n f{~"~ iS
Inorganic Chemistry
"
;;p,;- _i(~'",
; ' \ ___
================= II
Contin1UNS specmz. I comJlion
42
H2S20il) + H 20 (1) ==>
I
2~S04(1)
I
• continuous spectra a continuous spectrum consisting of a band of coloured light is produced when a narrow be f unli h' 11 d s h g t.IS a ~we to ~ass roug a pnsm. hn a clontlnUOUS spectrum, eac co our merges into the next, so that it is difficult to say where one colour ends and the next colour begins. Each colour corresponds to radiation of different energy.
am;
,.. 'f
I
: ~
II
movement occurs as a result of gravity, the hot part of the fluid expands, become less dense and is displaced by the colder d f fl d thi
d~:;~rt!~:~t. ~6rc: c~~ve~~
. . h h fl'd . non IS were ot ill IS trans~ ferred from one region to an; other by a pump. : ~ • coordination complex ; a coordination complex is a : compound in which molecules ~ or ions form coordinate bonds ; toa central metal atom or Ion. : The complex may contain positive ions, negative ions or neuI tral molecules. The formation of such coordination complexes is typical behaviour of TransiI tionMetals.
r
CHJ~C
1
I
j;~\) C~-::::CH
HJC....-L~
~
• convection convection is the process Py which heat is transferred from one part of a fluid to another by movement of the fluid itself. There are two methods in which this can be carried out. One is by na~ convection, in which
~ ; : ~
/
3+
,...,/t._
CH
Fe _v 00
J
d~ / II HJC/
~~
'CHJ
lris(2,4.penlanedionato)iron(IIIJ
. corrosIOn : corrosion is the chemical changes which occurs in a maI •
II ================_ IfW11/""" Chemistry
II corrosion cells I covalent borul terial over time due to its contact with air or moisture, and which result in the loss of physical strength and the mechanical properties of the material, rendering it unsuitable for its intended use. For example, metals are oxidised in moist air to their oxides which have low mechanical strength. • corrosion cells corrosion cells are the arrangements of electrodes and solutions which result in electrochemical changes to the contents of the cells. • coulomb the coulomb is the charge carried by a current ofone ampere flowing for a period ofone second.
43 ~ almost equal (i.e. it is formed ; by sharing electrons between : any two constituent atoms in a I : molecule such as the elements ~ in the middle of the periodic ; table, who do not lose or gain : electrons easily). Thus, in the ~ covalent bond, the Electron Pair ; in the covalent bond is shared ; equally between the atoms, so : that stable outer shells are cre~ ated in each atom by this sharI mg. I
88 ~
I
@ Covalent bond
I For example, in the chlorine • coupling reaction a coupling reaction is a chemi- ; molecule each chlorine atom cal reaction in which two mol- : contributes one electron from ecules join together to form a ~ its outer shell to form a shared ; pair, thus giving both a stable single product. : outer shell. • covalent bond ~ The atoms in carbon dioxide a covalent bond is the principal ~ are also covalently bonded. type of bond be~e~n atoms ; Each oxygen atom shares two whose ElectronegauVlty's are of : pairs of electrons with the carI
[nora""" CheMistry ===============-=
II
44
bon atom. Thus, there is a double covalent bond between the carbon atom and each oxygenatom.
COJ1tIlmt chlorUles I crystRJ lIIttiee "
critical pressure critical pressure is the pressure of a fluid at its critical state.
I •
I
• critical state • covalent chlorides the critical state of a fluid is the chlorides ofnon-metals (e.g. I when the liquid and gas phase phosphorus trichloride) are co- I both have the same density. In valent compounds. the critical state, the fluid is With the exception of carbon at its critical temperature, tetrachloride, these chlorides I critical pressure and critical fume in air and are readily hy- I volume. drolysed to yield either an acid or an acidic oxide. ; • critical temperature For example, phosphorus ~ the critical temperature is the trichloride fumes in air temperature above which a gas p~ + 3~O ==> ~P03 I cannot be liquefied by an in+ 3 HCI I crease m pressure. I • critical volume • cracking cracking is the process of break- I the critical volume is the voling down chemical compounds ume occupied by a fixed mass at high temperature. The term I of a fluid in its critical state. is applied particularly to the ~ • crude oil cracking of hydrocarbons in the I crude oil is the material exkerosene fraction obtained : tracted from oil wells and from petroleum refining to gi~e ~ which is subjected to a refming smaller hydrocarbons. ThIs ~ process to isolate various grades process involves the decompo- ; of fuels. sition of petroleum fractions ; • crystal lattice into hydrocarbons of lower molecular weight, by heating ~ crystal lattice are the regular them under pressure in the pattern of atoms, ions or molpresence of a suitable Catalyst. I ecules in a crystalline subI stance.
II = = = = = = = = = = = = 1'""1J_ie Chemistry
45
~ - cyclocyclo- is the prefix used in ~ chemical nomenclature to des: ignate a cyclic compound. I
I
.....
~H
Ct
o,tI( H2O
- crystallisation crystallisation is the precipitation of crystals of a solid from a supersaturated solution on cooled, when the solvent is unable to hold all the solute in solution. - crystals crystals are solids with regular polyhedral shape. All crystals of the same substance grow so that they have the same angles between their faces. - cubic lattice a cubic lattice is name for the unit cell of solid crystalline structure of Sodium Chloride, NaC!.
: - Dalton's atomic theory ~ a theory of chemical combina; tion, first stated by the British ~ chemist John Dalton (1766: 1844) in 1803. It involves the ~ following postulates: ; 1. elements consist of indivis: ible small particles (atoms). I : 2. all atoms of the same eleI ment are identical; different el~ ements have different types of : atom. ~ 3. atoms can neither be created I nor destroyed. ~ 4. 'Compound elements' (i.e.) : compounds) are formed when ~ atoms ofdifferent elements join ; in simple ratios to form 'com: pound atoms' (i.e.) molecules). ~ Dalton also proposed symbols ; for atoms of different elements : (later replaced by the present ~ notation using letters). I
: - daltonide ~ refers to a compound that con; forms to the laws of constant : composition and multiple proI . : portIons.
]IUJrganic
Chemistry
================='
II
46
. • daughter 1. a nuclide which is produced by radioactive *decay of some other Il.J.lClide (the parent). • -
~-:;..•=-.
:V: \
* . _.
"
," __
~
.... _. _/~" r:-.;..
_
I
deamination the term used for abstraction or replacement ofthe amino group in organic substances .
•
I
~
•
I
==:::-~ =:w.:=.,===:
: • debye effect ~ selective absorption ofhertzian ; waves h"l dielectrics, because of ~ app~ent existence of molecu: lar dipoles. I •
debye~huckel theory
2. an ion or free radical which ~ the activity coefficient of an is produced by dissociation or ~ electrolyte depe~d mark~dly reaction of some other (parent) ; upon. concentratIon. In dilu~e ion or radical. solutIon, due to the columblc I forces of attraction and repul• d-block elements sion of ions tend to surround refers to the transition elements them selves within the atmoof the ~st, se~ond, and third ~ sphere of oppositely charged long penods, ...e., Sc to Zn, Y I ions. Debye and Huckel to Cd, and La to.Hg. They are ~ showed that it was possible to so call~ because m gen~ra1 they : explain the abnormal activity have ~er d-Ievels WIth con- I coefficient at least for very difiguratIons of the type (n-I)tI' I lute solution of electrolytes. ns 2 wherex = 1.10. • dea~on process an earlier process which was ~ used for making chlorine by ; oxidising hydrogen chloride in air at 450°C using a copper chloride catalyst. It was pat- I ented in 1870 by Henry Deacon (1822-76).
Debye-Huckel Theory '"rkl.. ilof ....oII~ly ·· kT.'. sioll(x) - xso"" aliocarV"" Poin_IloIlzat_ r........ he ..'<Xl ~". &:"\'. "ilJ. ..: - 2e;,.ttkT, 111. ~"" is UAQf au ~I("". aM potcntil'.mltmd •• ingle to. in of wc:M.; dc:c&l'olyla. SoIaIioes tOr die. ~:IIC arc: \' • \ ·..."qI(••S) ,,1>crt j,
,i. U<>ooy.L"_"
or the double t.ycr",
1iI1·
IOM_
II dmlhytimte IMtJenemte
47
~ • defoliant • decahydrate a crystalline hydrate containing ; a chemical sprayed on plants that ten molecules ofwater per mol- ~ causes leaves to fall off prema: turely. Agent organ, a defoliant, ecule of compound. ~ was extensively used in the Viet• decalin ; nam war to defoliate jungles. obtained when naphthalene is ; • deformation energy reduced by hydrogen in the presence of nickel as a catalyst; ~ refers to the energy which must : be supplied to an initially first tetralin and them decalin ~ spherical nucleus to give it a is formed. ; certain deformation in the • decay : Bohr-Wheeler Theory. it describes how the activity of ~ • deformation potential a substance decreases with ~ effective electric potential acttime. ~ ing on a free electron in a metal • decrepitation ; or semiconductor resulting a crystalline solid gives crack_ ~ from a l~ deformation of the ing noise on heating due to the : crystallattlce. I removal of water of:. degenerate ~ describing different quantum crystallisation. ; states that have the same en• defect : ergy. For instance, the five drefers to any irregularity in the ~ orbitals in transition-metal lattice of a crystal. Two impor- I atom all have the same energy tant defects are: ~ but different values of the mag1. Schottky defects. Vacant site : netic quantum number m. Difwith the migrated atom at the ~ ferences in energy occur if a surface. ; magnetic field is applied or if 2. Frenkel defects. Vacant sites : the arrangement of electrons with an interstitial atom. ~ around the atom is not symI metrical. The degeneracy is ~ then said to be 'lifted'.
Intn1JII1Ii& Chemistry
================
II
48
• degradation a chemical reaction in which a molecule decomposes into simpler molecules, e.g., conversion ofamide into amine in the presence of bromine ad alcoholic KOH.
delocalisation refers to spreading out of bonding electrons in a molecule over the molecule.
I •
I
I
• delocalised bond (non-localised bond) a type of I bonding in molecules that is • degree of freedom occurring in addition to sigma from the standpoint of statisti- bonding. The electrons forming cal mechanics, a degree of free- ~ the delocalised bond are no dom means the independent ; longer regarded as remaining ways in which particle can take : between two atoms; i.e., the up energy, e.g., a mono-atomic ~ electron density of the gas has three translational de- I delocalised electrons is spread grees of freedom. From the over the whole molecule. standpoint of phase, it is the minimum number of variables I (e.g., pressure, temperatuce I and concentration) which must be fixed to define the complete state of a system. • dehydration . a process of removing water ~om a substance, e.~., dehydranon of ethyl ala:>hol.ffi the presence of sulphuriC aCid. • delayed proton refers to a proton emitted spontaneously from a nucleus as a consequence of excitation left from a previous radioactive decay event. II
I
. ; • delta bonding ~ lateral overlap between two or: bitals e.g.} d-orbitals such that ~ there are four regions of over; lap. ; • delta ray : refers to an electron or proton ejected by recoil when a rapidly I moving alpha particle of other
================= Inorganic Chemistry
II demj/UU1T1 reRrm"IJement I deaxyribo;UC""ICU""·""RC=id""(",,D,,,,!NA=)=====",,4~9 primary ionising particle passes ~ bristlecone pine (Pinus aristata), ; which lives up to 5000 years, through matter. : has been used to date specimen • demjanov rearrangement ~ over 8000 years old. Fossil refers to a structural rearrange~ specimen accurately dated by ment that accompanies treat; dendrochronology have been ment of certain primary ali:. used to make corrections to the phatic amines with nitrous acid; ~ carbon-dating technique. Denthe amine will undergo a ring ; drochronology trace elements in " contraction or expansion. : sections of rings can also pro• demulsification ~ vide formation on past atmothe process of breaking the ~ spheric pollution. emulsion by adding an electro- I • denitrification lyte or a material that would ; the rerurn of ftxed nitrogen, destroy the emulsifier. Heating : generally nitrates and ammofreezing or centrifugation may ~ nium salts, to the atmosphere also cause demulsification. ~ generally as Nzand N 2o. • dendrochronology an absolute dating technique using the growth rings of trees .. It depends on the fact that trees I in the same locality show a characteristic pattern of growth rings resulting from climatic I conditions. This it becomes pos- I sible to assign a defInite date for each growth ring in living trees, and to use the ring patterns to ~ date fossil trees or specimens of ; • deoxyribo nucleic acid woo d (e.g.) used for buildings: (DNA) or objects on archaeological ~ a nucleic acid, a polymer of sites) with life-spans that over- ; nucleotides. Incorporates phoslap those of living trees. The ~ phoric acid, deoxyribose, and [norDllnic Chemistry
=============....=== II
50
nitrogenous bases such as ad- ~ • desulphorisation enine, guanine cytosine, and I a process which involves the thymine. Found in the cell : removal ofsulphur compounds nucleus. Plays an important ~ from petroleum fractions in the · part in heredity mechanism. ~ presence of a catalyst. (Also The Watson-Crlck ; known as hydrotreating or Model of DNA (19S3) ..1_ fining) .. hywe . I
~~ (lnIIcIe) A + T
G+C
: • detonating gas ~ it is a mixture of~ and O 2in a ~ ratio of2:1. It is produced by ; electrolysis of water. It : explodgs violently to reform I . .. : water, on IgrutlOn. ~ • detonation
• depolarisation I means the prevention or de- ~ crease ofpolarisation in electro- : lytic cells and ion current ~ sources with the help of; depolarisers added to electro- : lyte or electrodes. Oxidiscrs ~ find use to depolarise cathodes, ~ and reducing agents with an- ; odes. ; • derived unit : refers to a unit defmed terms ~ of base units, and not directly ~ from a standard value of the ; quantity it measures. e.g., the: • • fl:. defIned newton IS a urut 0 loree. metre second-2 asa kilog ram ' (kg ms-2). ~
refers to an exothermic chemical reaction that propagates with such rapidity the rare of advance of the reaction zone into the unreacted material exceeds. The velocity of sound in the unreacted material, i.e., the advancing reaction zone is preceded by a shock wave. • deuterated compound a compound in which one or more IH atoms have been replaced by deuterium (2H) atoms. d . eutenum . . a naturally occurrmg ISOtOpe of " I I hdr Y' ogen, It IS a co our ess gas
I.
51 having twice the density of ordinary hydrogen. It is chemically less reactive than hydrogen. _ devitrification
~ - dextran ; the temperature at which a mix~ ture of air ~d water vapour is : saturated WIth respect to water I : vapour.
loss ofthe amorphous nature of ~ - dextrin glass as a result of; intermediate product formed crystallisation. : during the hydrolysis of starch ~ to sugars. Used as adhesives. - dew point the temperature at which a mixture of air and water vapour is saturated with respect to water vapour.
I
: - dextrose (grape-sugar) ~ refers to a naturally occurring ; glucose, belongs to the stere: ochemical series D and is dex- dewar flask (vacuum flask) ~ trorotatory indicated by the refers to a double walled con- ~ symbol ( + ). Thus the term dextainer of thin glass with the ; trose is used to indicate D- ( + ) : glucose. space between the walls evacu- I ated and sealed to stop conduc- : - diagonal relationship tion and convection of energy ~ it refers to the similarities in ~ properties shown by the first ; element of a group to the sec: ond element of second period. ~ e.g., Li to Mg, Be to AI, B to Si I etc. ~ - diamagnetism ; the property of all substances : that causes repulsion ofthe sub~ stance from a magnetic field. ; Originates in the inter-action of through it. The glass is often : the electronic charge and the silvered to reduce radiation. ~ field and is an additive property
Inorgllnic Chemistry
================= II
52
diamond I Dibereiner's trUuIs "
~==~===~*
of the atoms and groups present. Order of magnitude 10.3 that of paramagnetism so that the effect is swamped by the presence of unpaired electrons.
~
(N2 ), and the halogens are ex; amples of diatomic elements. : • Diazonium compounds ~ important type of compounds I containing the RN = NX I groups, where R is aromatic I group and X a negative group. : • dibasic ~ compounds containing two hyI ~ drogens that may be replaced : by a monovalent metal or radical. An alcohol that has two hyI ; droxyl groups, e.g., ethylene : glycol.
• diamond an allotropic modification of carbon. It is the hardest substance known. In it, each carbon atoms is Sp3 hybridised. Each carbon atom is covalently bonded to four other carbon atoms resulting in a three dimensional network of covalent bonds. It is used in jewellery, I • Dibereiner's triads for cutting glass, as a rock drill, I triads of chemically similar eleas an abrasive etc. I ments in which the central nUmber, when placed in order of increasing atomic weight, has an I atomic weight approximately I equal to the average of the outer two. Other chemical and physiDlo.md Crt IIcol Nel Olooond Crl tlcol Net cal properties of the central I number also lie between those • diaspore an important constituent of ~ of the first and last numbers of bauxite. . the triad. Dobereiner noted this relationship in 1817; the triads • diatomic I are now recognized as consecudescribing a molecule that con- tive numbers of a group of the sists of two atoms. Hydrogen periodic table; e.g.) Ca, Sr, and (H2 ), oxygen (0 2 ), nitrogen I Ba and el, Br, and I.
II ================= InorDlm" Chemistry
II dibomne I dielectric properties
53
*================
_ diborane
~ - dichroism
B2H 6, a colourless, volatile com- I the property of some crystals, poW1d that is soluble in ether; such as tourmaline, of selecboiling point-92.5°C, melting tively absorbing light vibrations point -16S.So C; can be used to I in one plane while allowing produce pentaborane and I light vibrations at right angles decaborane, proposed for use as to this plane to pass through. rocket fuels; also used to synthe- ~ Polaroid is a synthetic dichroic size organic boron compoW1ds. I material. Also known as boroethane; ~ - dichromate (vi) diboron hexahydride. ; a salt containing the ion Cr2 7" : . Dichromates are strong ~ oxidising agents. 119pm .I _ dichronuc ° act°d
°
·K .·.· ·"·)
Dt"borane
'.
.\
./
.'
~ H 2Cr20 7, an acid known only ; in solution, especially in the ; form of dichromates . I
; - dielectric ~ a material which is an electrical _ dichloramine I insulator or in which an electric 1. NH2 CI2 , an unstable molecule considered to be formed ; field can be sustained with a from ammonia by the action :I minimum dissipation of power. of chlorine. Also known as : - dielectric constant I , chlorimide. : reciprocal ofthe force of attrac2. any chloramine with two I tion between two electric chlorine atoms jointed to the ; charges of W1it value separated nitrogen atom. ; by a distance of I centimeter. I - dichloride : - dielectric properties any inorganic salt or organic ~ a dielectric is a substance in compoW1d that has two chloride ~ which an electric field gives rise atoms in its molecule. EIha..
InD1l1"nic Chemistry
================== II
~54! ! ! ! ! ! ~! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ~tliel~~ a~' JltJpourtletector ItlijfnlaionJNIItem II to no net flow ofelectric chaFge. The substance having dielectric properties shows piezoelectric effect. • dielectric vapour detector refers to an apparatus to measure the chan e in the dielectric g constant of gases ,of gas mixtures, used as a detector in gas chromatographs to sense changes in carrier gas. • dielectronic recombination the combination of an electron with a positive-ion in a gas; thus the energy released is taken up by two electrons of the resultingatom.
• dielectrophoresis refers to the ability of an unchanged material to move when subjected to an electric field.
~
• differential extraction
the process in which a component from a mixture can be taken out part by part by solI vent or any other means. In orI der to extract another compoI nent, the solvent or other.simi: lar means correspondmgly I
~ change. differential manometer a manometer that is used for the measurement of differences of pressure, e.g., between the ~ vapour pressure ofa solvent and its solution. I I •
.~
I
• dienophile I refers to an alkene compound : in a reaction when an alkene ~ reacts with a diene. • diffraction pattern I the pattern obtained on a phoI tographic plate when a beam of : X-rays or electrons is passed ~ through a crystal. It is used for I the study of crystal structures.
II ================= l1Wf1Jlmie Chemistry
II dihytlmte Idil.aion
55 ~
acidic properties and exist in ; keto and enol forms.
Tht" Dill'rdction Pattern
;~ ..
/~:-i : :
~
- -:-::::-.:-..:::-:.-:.:"'-....
s-- of x...,.,
0ytUl
\
• dihydrate a crystalline compound which contains two molecules of water of crystallisation per molecule of compound. • dihydrogen molecular hydrogen, H 2• It is a colourless, odourless gas and is used as a rocket fuel in liquid form. It is also used in hydrogenation of vegetable oils.
; • dilatant ; a material with the ability to : increase in volume when its ~ shape is changed. ~ • dilatometer
; an apparatus for measuring ; small changes of volume of a : liquid, solution or solid im~ mersed in a liquid. I I
• di-iodide a molecule that contains two ~ • dilute iodine atoms bonded to an ele~ denoting a solution in which the ment or radical. ; amount of solute is low relative • diketones : to that of the solvent. The term organic compounds having two ~ is always relative and includes keto (>C = 0) groups. Show I dilution at trace level as well as ; the common term 'bench dilute : acid', which usually means a 2M ~ solution.
#. ,
\
.... / '"
-
IntI'lJllnic Chemistry
~
\.
...
~
• dilution ; refers to the volume of solvent ; in which a given amowlt of sol: ute is dissolved.
================= II
*
56
dimethylmnine I dipolemoment
II
• dimethyl amine ~ a colourless gas with an ammo- I niacal smell. It is used in ~ dehairing hides and as a rubber: accelerator. ~
• dioxygen 02 formally the oxygen molecule but used for dioxygen complexes and dioxygenyl, (02)+' salts.
~
; ;
• dioxygenyl compounds compounds containing the posirive ion 0/ as in dioxygenyl hexafluoroplatinate 02PtF6 an organic solid that sublimes in vacuum at 100°C. • dipole moment
• dinitrogen tetraoxide ~ (N2 a colourless gas that changes ~ to a pale yellow liquid below; 21°C and solidifies below : 11°C. It is used as a nitrating ~ agent. ~ • diodine hexachloride ; : ref~rs to a powder ~ade .by ~e- ~ a~g ex~ess chlorme ~I~ .10- ; dine. It IS a st!O~g ?Xldi~mg ; ~gen~ an~ at 70 C It dis~oclates : mto Iodine monochlonde and I chlorine. ~ • diol (dihydric alcohol, : ~ glycol) refers to an alcohol that has two ; hydroxyl groups (-OR) per : ~ molecule of compound.
in a heteronuclear diat~mic molecule, because of the difference in electronegativities of the two atoms, one atom acquires a small positive charge (qJ, the other a negative charge (q.). The molecule is then said to have a dipole moment whose magnitude ?=qd, where d is the distance of separation of the charges. With polyatomic molecules, the net dipole moment is the vector sum of the dipole moments of the individual bonds within the molecule. Thus symmetrical molecules, e.g.) CCI" may contain polar bonds but"possess no dipole moment. Measurements of dipole moments may be of
• dinitrogen oxide ( ni tro us oxide, N 2 a colourless gas with a faintly sweet odour and taste. It is prepared commercially and in the laboratory by the careful hearing of ammonium nitrate:
°),
°,)
; ~
: ~
:
I
II ================_ I"DrlJ"n" Chemistry
II direct dyes I dispersing R!Jcnt
57
use to give information about ~ 4S-S0DC and the fabric added. the structure of complex mol- ; By modifying the method of ecules. : application, it is possible to I . : dye polyacrylic and polyester • direct dyes ~ fibres. The yellow/orange a group of dyes obtained from ; shades are; nitroarylamine debenzene or benzidene. These : rivatives and t are used to dye cotton, viscous rayon and other cellulose fibres ~ he green to bluish shades are directly in the presence ofNaCl I derivatives of I-amino anor sodiwn sulphate as mordant. ~ thraquinone. Certain azo : compounds are disperse dyes • direct effect ~ and these give a range of refers to a chemical effect ; colours. caused bv the direct transfer of: di . d'· spersmg agent energy firom lOrusmg ra lanon . to an atom or molecule in a ; a substance used in the promediwn. : duction of emulsions or dis~ persions of immiscible liquids • disinfectants I or liquids and solids. The disthose chemical substances ~ persing agent may lower the whichcandestroyorkillmicro- : interfacial surface tension organism or stop their growth ~ (surface tension depressant) ~ut are also harmful to hwnan ; or increase the viscosity of the tlSsu~: Such substan~ are used ~ continuous phase (protective to disinfect floors, toilets etc. : colloid). e.g., phenol (1%), S02(g) etc. ~ Dispersing agents, such as • disperse dyes ; polyethylene polyamide succwater insoluble dyes, which, ~ inimides or methacrylate type when held in fine suspension, : copolymers, are added to mocan be applied to acetate rayon ~ tor oils to disperse 'low-temfabrics. The dye, together; perature sludge' formed in with a dispersing agent, is ~ spark-ignition-engines. warmed to a temperature of : J
•
lnorollnic Chemistry
••
I.
================= II
- displacement series the elements in decreasing order of their negative potentials. Also known as constant series; electromotive series; Volta senes.
I
I
- disproportionation a process in which a compound of one oxidation state changes to compounds of two or more I oxidation states, e.g., I 2Cu+ = = > Cu + C~ + in aque- : - dithionate ous solution. Alternatively, re- ~ a salt ofdithionic acid, containdistributionofgroupsarounda I ing the ion S2062- usually central atom, e.g., formed by the oxidation of a 2PF4CI = = > PF3C~ +PF5 sulphite using manganese re_ dissociation pressure ducing properties. the pressure for a given tem- ~ _ dithionic acid perature at which a chemical I H S 0 a strong acid fomed · . 2 2 6' compounddissoaates. ; by the oxidation of sulphurous - distillate ; acid, and known only by its salts the material generally liquid, that : and in solution. is vapourised ~d.co~densed in ~ _ ditungsten carbide the process ofdistillanon. ~ W 2C, a grey powder having - distillation I hardness approaching that of refers to a process of boiling diamond; forms hexagonal a liquid and condensing the crystals with specific gravity vapour. Distillation is used to : 17.2; melting point 2850°C. purify liquids or to separate ~ _ di al t (b· al t) ·d· v en lV en components of a Iiqw mlX-; h · al f avmg a v ency 0 two. ture.
IliUM I
59
doublet
• d-lines two close lines in the yellow region of the visible spectrum of sodium, having wavelengths 589.6 nm. As they are prominent an~ easily rec~~, they are use as a stan ar m spectroscopy. • donor an ion or molerule that provides a pair of electrons in forming a coordinate bond. • dopamine a catecholamine that is a precursor in the synthesis of nonadrenaline and adrenaline. It is also believed to function as neurotransmitter in the brain. • doping the na.tllC given .to the practi~e whereby electnc~, ma~e~c
an~otherpropertleSOf~lOruc
solid may be changed by mcorporation of ~ intervalent .ion in the h?st lattIce. e.g. the mcorporatlon of small amounts of . th . 1- I L 1·+ or Ga3+ mto e ruCl\.e oxide lattice results in a respective decrease or increase in conductivity of the latter. When the dopant is not incorporated di-
~ rectly into the lattice, but rather
; forms discrete aggregations : within it, the process is referred ~ to as domain doping. ~ • double refraction ~ refers to the property which is ; possessed by certain crystals : (notably calcite), offonning two ~ refracted rays from a single in~ cident ray. The ordinary ray ; obeys the normal laws of remc: tion. The other refracted ray, ~ called the extraordinary ray, fol; lows different laws. ; • double salt ~ a salt formed by crystallisation : from a solution of two or more ~ components that has distinct ; properties in the solid but in : solution behaves as a mixture ~ ofthe components. e.g. iron (IT) I ammonium sulphate, FeS0 4 ~ (NH4)2' S046H20. Double : salts are either weak, easily dis~ sociated complexes or the solid I lattice which have an extensive : interaction e.n. hvdrogen bondI 'v J . ing not found in the c _ ; ne~ts ompo : . ~ • doublet ; a pair of associated lines in cer~ tain spectra, e.g., the two lines
=
1'""11l1ni& Chemistry ________________________________
II
60
that make up the sodium Dlines. ., dry cell refers to a, voltaic cell in which the electrolytic is in the form of a jelly or paste. The Leclanche
dry cell I dymuffi
II
~ directlytoagasat-78.5°Cas ; heat is absorbed . ; _ ductility ~ the ability of a material to be : plastically deformed byelonga~ tion, without fracture. A prop; erty by which materials can be : drawn into wires. Silver and ~ gold are highly ductile. I
: - duplet ~ a pair of electrons in a covalent ; chemical bond. ; - duralumin
' . . . dry c~ll1S extensIvely used for flas~g~ts and other portable applicattons. _ dry cleaning the process of cleaning fabrics using solvents which dissolve dirt at low temperatures but d~ not swell fibr~s. Th~ most WIdely used cleanmg flwds are the highly inflammable hydrocarbons and chlorinated hydrocarbons, particularly C CI .
~ (~rademark), a strong light-
: ~ ; :
~ ~
; ~ :
weight aluminium alloy conraining 3-4% copper, with small amounts of magnesium, manganese, and sometimes silicon. It is widely used in aircraft bodies. _ dutch metal a Cu-Zn alloy prepared in leaf form in imitation of gold-leaf.
~
. - dyestuffs ~ intensely coloured compounds ~ applied to a substrate, e.g., fi2 4. ; bre, paper, cosmetic, hair, to - dry Ice. . . . ~ give colour. React by absorpcarbon dIOxIde I~ the solId : tion, solution, bonding. Pigform, usually made m blocks to I ments retain their identity be used as a coolant; changes more closely on bonding to the
II ================__ 11IOflI-ie Chemistry
" dynR-mite I earth's enut
61
*==============~ substrate. Colours generally ~ Mars, and has three distinct lay-
originate in electronic trans i- I ers. tions; most dyestuffs are organic in nature but are frequently applied together with I inorganic species. Classified in the colour index by chemical nature; also classified by tlleir I method of application as acid, I basic, direct, disperse, aw, sulphur, vat or fibre reactive. • dynamite ~ the gaseous atmosphere, ; the liquid hydrosphere, and any of a class of high explosives . . : the solid lithosphere which has based on mtroglycenn. The I thr di . .' . . al c. . d· 1867· ee stmct reglOns ongm 10rm mvente m .I the crust (EarthCrust ), . by Alfred Nobel, consIsted of : th tl (E rthM tl) d nitroglycerin absorbed in kie- ~ the man (BearthaCo an) e an . . e core re . seIg uh r. M 0 d ern d ynamltes, I which are used for blasting con- : • earth's atmosphere tain sodium or ammonium ni- ~ earth's atmosphere is the layer trate sensitised with nitroglyc- I of gasses that surrounds the erin and use other absorbers ~ earth. (e.g.) wood pulp). ~ • earth's core • dynel or vinyon : earth's core, part of which is a copolymer ofacrylonitrile and ~ believe to be liquid, lies below vinyl chloride containing about I the mantle. equimol~ quantities of the two I • earth's crust monomers and can be spun into ; earth's Crust has a mean thickfibre from acetone solution. : ness of about 32 km under the • earth ~ land and 10 km under the sea, planet Earth orbits the sun be- I and has the approximate chemitween ·the planets Venus and ~ cal composition: InOTB"nic Chemistry
================= II
",,6~2~~~~~~~~~~eR~rt:mRntle I ~~rtliRMeter II ~
Oxygen Silicon
47%
~
28% 8%
I
- effective atomic number rule
~ applied to transition metal : carbonyls and to many orgaIron ~ nometallic derivatives. It is Calciutn ; frequently found that the toSodium tal number of electrons availPotassium able to the central atom from Magnesium I its own electrons, by donation - earth's mande I (lone pairs, etc. of electrons earth's mantle extends some: from ?-bonding systems), by 2900 kmbelow the crust. , ~ covalent bonding (each covaI lent bond to a substituent or ~ another metal contributes I : electron), and taking into ac~ count charge add up to the ; total number of electrons of : the next noble gas. This does I . spe: not app1y to paramagnenc ~ cies and there are many other ; exceptions to the rule. e.g., - ebullioscopy : CIMn(CO)s.Mn7 valence a process used for the determi- ~ electrons, I from covalent nation of molecular weight ~ bond to CI, 5 x 2 electrons from elevation of boiling point ; from carbonyls. Total 18 elecof solution. : trons, krypton structure.
Aluminium
4.5% 3.5% 2.5% 2.5% 2.2%
I
_ edeleanu process : I an extraction method utilizing: liquid sulphur dioxide for the ~ removal of aromatic hydrocar- ; boos and polar molecules from ~ petr0 1eum firactl·oos.
- effective molecular diameter the general extent of. the electron cloud surroundi~g a gas molecule as calculated ill any of several ways.
II ================_ ImwolJni& Chemistry
II
effirvescmee I elearochemictd cell
63 *==~~~~~~~
- effervescence effervescence is the formation of gas bubbles in a liquid by chemical reaction. An example of effervescence is the release of carbon dioxide whi~h bubbles as a gas fro~ the ~quid when limestone chi?s, which are composed of calc~um carbonate are added to dilute hydrochloric acid. _ efforescence efforescence is the process where a crystalline hydrate loses water, forming a powdery deposit on the crystals. - effusion effusion is the flow of a gas through a small aperture. The relative rates at which gases effuse, under the same conditions, is approximately inversely proportio~al to .t?e square roots of therr denslttes. - Einstein it is a unit of radiant energy named after a great scientist.
~ tripositive actinide, EsCI 3,
; EsOCI and ES20 3 are known. ~ EsBr2 is reduced to EsBr3 by : hydrogen. ~ _ Elaidinisation ~ refers to the process of chang; ing the geometric form of an : unsaturated fatty acid or a com~ pound related to it into the I transform, resulting in an acid :I that is more resistant to oxida: tion. I : _ electret .~ refers to a permanently electri; fied substance or body that has ~ opposite charges at its extremi: ties. I : _ electrical conductivity ~ refers to the ability of sub; stances to transmit electricity : under the action of an external ~ electrical field. If electrons are ~ charge carriers as, e.g., in met; als and most semiconductors, : the phenomenon is termed as ~ electronic conductivity. ~ _ electrochemical cell
- Einsteinium compounds I an Electrochemical Cell consists the element shows oxidation ~ of a pair of electrodes imstates of + 2 and + 3, the + 3 ~ mersed din solutiondso~ electrostate being that of a typical : lytes an connecte VIa an ex-
lmn;gllni& Chemistry
================= II
electrrJc:ical corrosion I electrochemical series
64
II
ternal metallic conductor such ~ • electrochemical equivalent an arrangement is called an ; the Electrochemical Equivalent electrochemical cell. :I of a substance is the mass of the substance, in grams, which is ~ liberated by the passage of 1 ; coulomb of electricity. -.,
--
~
: ~
.:=--.. . . . . . . . . . . . .
It ......... ~ . .01
.:.~ . . . . . . . . . . . . . . . . . . . . It . . . . . . , ..... · 4......,.~
electrochemical series the electrochemical series consists of a list of metals have been arranged in order of their standard electrode potentials. The standard electrode potentials which has been measured for most elements that form ions in solution. Metals which are hi~her.in the electroch~mical senes ~place metals which are lo~er m the s~quence from solunons of theIr salts. The electrochemical series The following is a list of the standard potentials:
I •
......... ............. ~
~lt
.~~-=.:::"'-.-.--...,......,.,. • .."....-caI ... .
; : ~ I
If the cell is used as a source of ~ electrical energy, (i.e. if it con- I verts the free energy of a physi- : cal or chemical change into elec- ~ trical free energy) it is called a . ~ Galvanic Cells. ' If the cell is used to achieve a ~ change in the physical or chemi- ; cal composition of the constitu- ~. ents of the cell by the applica- : Element tion of electrical energy from ~ Electrode Potential (Volts) some external source, it is called ; ============== an Electrolytic Cell. I Lithium -3.04 • electrochemical corrosion ; Rubidium -2.92 it involves deterioration of : Potassium -2.92 metal due to flow of electric ~ Calcium -2.87 current from one point to an- I Barium -2.80 other point. Sodium -2.71
II ================= Inorgllnk Chemistry
II elearrJchemimy I electrochemistry Magnesium -2.37 Aluminium -1.67 -2.34 Mangnesium -0.76 Zinc -0.74 Chromium -0.44 Iron -0.24 Nickel -0.14 Tin -0.13 Lead +0.00 Hydrogen +0.34 Copper +0.54 Iodine Silver +0.80 Gold +0.80 Mercury +0.80 Iodide +0.54 Bromine +1.07 +1.36 Chlorine Fluorine +2.87 A negative value for electrode potential means that the element loses electrons more readily than hydrogen (i.e. it is betterreducing agent). A positive value for electrode potential means that the element is a poor reducing agent than hydrogen. A strong oxidising agent has a large positive potential and a strong reducing agent a large negative potential.
lnoralJni& Cbemistry
•
~~~~~~~~~6~5
~ The electrochemical series is ; extremely useful for predicting ~ the chemical behaviour of an : element. An electropositive el~ ement will displace a less elec; tropositive element from a so~ lution of its ions (e.g. zinc will : displace copper from a copper ~ solution). ; However, aluminium which is : more electropositive than copI . : per does not displace copper ~ from copper salt solutions, due ; to the presence of a very stable : film of aluminium oxide on the ~ surface ofthe aluminium which ~ has a lower electrode potential. ; This oxide film can be de: stroyed by the presence of ~ added chlorine ions. Thus, in ~ the presence of added chloride ; ions in the solution, copper is : deposited and the aluminium ~ dissolves. I
: - electrochemistry ~ electrochemistry is the study of I the effects of electric current on ~ the properties and reactions of : chemical substances in solution, ~ including electrolysis and elecI tric cells.
================ II
66
elemvtIe I elemvtIejIt1tmhRl
~~~~~~~~*
• electrode ~ an electrode is a conductor that I emits or collects electrons in a ~ cell. The anode is the positive : electrode, where ions lose elec- ~ tronsand thus, oxidation occurs ; at the anode. The cathode is the ~ negative electrode, where ions : gain electrons and thus reduc- I tion occurs at'the cathode. ~ . : • electrode potenti~ . ~ the electrode potential (I.e. the . Reduction Potential) of a half ~ cell is a measure of the pote~- ~ tial for an element to lose Its ; electrons when in contact with : a solution of its ions. It is not ~ possible to measure. the elec- ~ trode potential of a smgle elec- ; trode, so two h~lf-cells are : joined and the difference be- ~ tween their electrode potentials ; is measured. If the electrode : potential is known for one of ~ the half cells, that of the other I may be calculated. The standard ~ half-cell chosen as a refere~ce : is the hydrogen half cell, which ~ is assigned an electrode poten- I tial of zero. The hydrogen cell : consists of a platinum electrode ~ coated with platinum black con- ~ taining absorbed hydrogen 0
II
which catalyses the half-cell reaction. 2H + :-. 2e = = > H2 T~e ~bihty of an ele~ent to ~ madised or r~duced m a cell IS used to obtam a. value for the electr~d~ potential .. If an electrode IS unm~rse~ m one molac hydrochlonc aad and hydrogen gas at a pressure of 1 atmosphere is bubbled over the platinum black electrode to maintain equilibrium, it is possible to obtain a value for the electrode potential of any element. For example, if a hydrogen half cell is connected to a copper half-cell, (i.e. a copper rod in a solution ofcopper ions) and the potential of the cell measured, it is found to be +0.34 volts, and assigned as the electrode potential ofthe copper halfcell, using the following convention. If the metal electrode loses electrons more readily than the hydrogen electrode, the metal eventually acquires a negative potential due to the accumulation of electrons on the metal. If the metal electrode does not form ions as readily as the hyo
67
I! electrodeposition I electrolytic cell drogen electrode, the metal appears positive with respect to the hydrogen electrode. Standard electrode potentials have been measured for most elements that form ions in solution. A negative value for electrode potential means that such an element loses electrons more readily than hydrogen (i.e. it is a better reducing agent). A positive value means the element is a poorer reducing agent than hydrogen. Thus, strong oxidisjng agent has a large positive potential and a strong reducing agent a large negative potential.
~
; :
~
I
; : ~ I
~ :
electrons to form neutral species. Alternatively, atoms of the electrode can lose electrons and go into solution as positive ions. In either case, anodic reactions are oxidation reactions. At the cathode, positive ions in solution can gain electrons to form neutral species. Thus, cathodic reactions are reduction reactions.
I
I
......
-I ~u I
~ • electrodeposition : refers to the process of depos- ~ iting one metal on another by ; electrolysis, as in electroform- ~ ing and electroplating. : • electrolysis ~ electroly.,is is the production of ~ a chemical change by electrical . · .. ~ energy. In eIectroIYSIS, posltlve· ions migrate to the cathode and ~ negative ions migrate to the ~ anode. At the anode, the nega- ; tive ions in solution may lose :
=
IL
-- .......
..,.,
(
• electro~yte an electrolyte is a compound which conducts an electric current when in solution or in the molten state, and is simultaneously decomposed by the current. In contrast' ~ith ~etals where the c.urrent IS carnedby electrons, m electrolytes the current is carried by the ions . . th h th r 'd ffilgratmg roug e lQW . • electrolytic cell an electrolytic cell is one in which a physical or chemical
I
ltwrgani& Chemistry
================= II
68
electrolytic corrosion I eIectnm "
change is caused by electrical ~ visible radiation energy applied from some ex- ; (4 x 10-7 to 7x 10-7 meters), ternal source. : ultraviolet waves (10- 7- to 10-9 meters) and ~ X-rays and gamma radiation ; (10-9 to 10-14 meters).
--
.-.-
• electrolytic corrosion electrolytic corrosion ofa metal occurs through electrochemical reactions. • electrolytic gas electrolytic gas is the highly explosive gas formed by the electrolysis of water. It consists of two pans hydrogen and one part oxygen by volume. . • electromagnetic spectrum the electromagnetic spectrum is the range of wavelengths over which electromagnetic radia tion extends. The spectrum includes radio waves (105 to 10-3 meters), the longest waves, infrared waves (10-3-10-6 meters), next longest,
; • electrometallurgy : the uses of electrical processes ~ in the separation of metals ~ from their ores, the refIning of ; metals, or the forming or plat: ing of metals. ~ • electron ~ the electron is an atomic par~ ticle. It travels in the orbitals ; about the nucleus, which is the ; cenn:u core ?f the atom. It ~ : a umt negatIve charge ~d Its ~ mass is only. 1/1850 tha~of~e ; proton. ~t IS ch.aractensed m : terms of Its parttcle and waveI like properties. : I : Atomic Structure 1 I
nUcieus-0---'. _ I
@
I
~
a
0
m_um of2 oIecWns
~~
m_um 018 eledrcns
3"'ohel
m_um of 8 eleaans
4 .-
II = = = = = = = = = = [nora''''" chemistry
II
electron affinity I electron affinity
• electron affinity the electron affinity of an element is the energy released when an electron is added to a neutral gaseous atom of that element. It is measured in electron volts. The values of the electron affmities are difficult to determine, but some have been obtained by a method involving the Born-Haber Cycle. The fluorine and chlorine atoms can each readily acquire an electron to form the fluoride and chloride ions, respectively. These ions have the Electronic Configuration of the noble gases (i.e. a full outer valency shell), and are therefore stable ions. The reason for this is that the fluorine and chlorine atoms can accommodate an electron in . 2 d3 b" als thelr pan p or It respec"ly and th at the attractIon . 0f tIve the positively charged nucleus is great enough to overcome the repulsion from the other five electrons. A list of values for the electron affmities of fluorine, chlorine, bromine, iodine, hydrogen, oxygen and sulphur is given below.
69
•
~ Table of Electron Affinity (eV) 1
~ F
+ e( -) : CI + e( -) ~ Br + e( -)
F (-) - 3.62 CI( -) - 3.79 Br( -) - 3.56 1 I + e( -) I( -) - 3.28 ~ H + e( -) H( -) - 0.77 : 0 + 2 e( -) 0(2-) + 7.28 ~ S + 2 e( -) S(2-)+ 3.44 ; The Electron Affmity for an el~ ement depends on the atomic : radius, the nuclear charge, and ~ the screening effect ofinner lay1 ers of electrons. ~ The decrease in value of the : Electron Affmity on going from ~ chlorine to iodine is reasonable, 1 because the electron added to I: the iodine goes into the fifth : level and is less tightly bound ~ to the nucleus. Hence the addi" " " I tIon of thIS electron releases :I I ess energy. " ; For the el~ments oxygen ~d : ~ulphur which form di~negatIve ~ Ions, the ~lectron affllllty values 1 are negatIve. Although energy : is released when one extra elec~ tron is added, much more en1 ergy is required to force the sec~ ond electron into an ionised : atom. 1
Inorganic Chemistry
================= II
!!!!!70~~~~~~~~~ele&!!!!!;compMmtls I elearonJlllirwpulsion II The electron affinity for the alkali elements of Group 1 are assumed to be zero. Electron Deficient Compound An electron deficient compound is one in which there are fewer electrons forming the chemical bonds ~ required in normal electron-parr bonds.
~
; :
~
~
; :
~ I
was used by Davission and Germer to demonstrate that electrons have wave properties. Electron diffraction fmds use to study molecular structure, especially in the gas phase and the investigation of surfaces. _ electron microscope . .
: the electron ffilCroSCOpe IS a - electron compounds I form of microscope that uses a compounds which are formed ~ by transition metals and one of : the main group elements in ~ which the structure of particu- ; lar phases depends on the ratio : I of the total valency electrons : available to the total number of I atoms in the simrlest empirical ; formula (making assumptions : such that Fe, Co, Ni group ele- ~ ments have 0, eu group 1 va- I . lence electrons). The ratios are ~ beam of ~Iectro~ lDSte.ad of.a 3:2,21 ; 13 (y-phase complex), : beam of light (as m opncal~7: 4. I croscope) to form a large lffi: age of a very small object. _ electron diffraction I : - electron pair repulsion w hen we allow beam 0 f eIec- I trons to interact with atoms or ~ electron pair repulsion is the molecules, because of the wave : divergent force between the properties of the electrons, they ~ electron pairs in the sub-orbitget diffracted. The diffraction of ; als of the valence shell about an a beam of electrons by the sur- : atom. The~e are two types of face of a nickel single crystal ~ .electron parrs :
II ================_ l1W'1Ja,," Ch_istry
II eleetrrm jHJirs I eleetrrm pairs
71 *~~~~~~~~
Bond Pairs : where the electron pair are shared in a covalent bond, Lone Pairs : where the electron pair are not shared in any bond. There are three types of interaction between these different types of electron pairs : bond pair : bond pair repulsion (bp:bp) where both electron pairs are shared in covalent bonds, lone pair : lone pair repulsion (lp:lp) where both electron pairs are not shared in any bond, and lone pair : bonding pair repulsion (Ip: bp) where one electron pairs are
~
further away from the central atom. : Repulsion between electron ~ pairs is inversely proportional I to the distance between them. ; The repulsion between electron : pairs influence the shape of ~ simple covalent molecules, be; cause the presence of a lone pair ~ in a mo~ecule tends to cause : bond parrs to come closer to~ gether. This will result in ; smaller bond angles in the mol: ecule; since it is the angle be~ tween the bond pairs which dic~ tates the bond angle. 1 . ~ • e ectron parrs I
; electron pairs are the two elec: trons which have opposite spins ~ that occupy the same sub-orshared in a covalent bond, and I bital in the valence shell of an the other electron pair is not shared in any bond. ~ atom, or in the single covalent : bond between atoms. The magnitude ofthe repulsion I .......... ,..... force between electron p,airs Namo (boftcI., .......... bMdlllg)
depend on the proximity of each pair to the central atom. Lone pairs lie closer to the central atom than bond pairs, since lone pairs have no other nearby positive nucleus to attract them away from the centre. Bond pairs are attracted by a second nucleus and so they are drawn Inorganic Chemistry
I I
S,",ctv ...
....
:-M-:
r
«'M....••
I
l21li'
Trigonal Planer
Te_odrGI
Trigonal Blpyranldol
I
================= II
Y ""7""2========""elec=t,,,,,ron;bemicroanal sis I e/earrnu>eatiflity "
- electron probe mi~ croanalysis electron probe microanalysis, ~ EPM, is the method of: analysing a very small quantity ~ (i.e. as little as 10-13 gram) of a ; substance. The method consists : of directing a very fmely fo- ~ cused beam of electrons on to ~ the sample to produce the char- ; acteristic X-ray spectrum of the : elements present in the sample. ~ It can be used quantitatively for ~ elements with atomic numbers ; : in excess ofl1.
- electron-deficient COIDpounds compounds in which the number of electrons available for bonding is insufficient for the bonds to consist ofconventional two-electron covalent bonds. Diborane, B2H 6 , is an example in which each boron atom has two terminal hydrogen atoms bo~d by conventional electronpaIr bonds and in addition the molec~e ~as two hydrogen atoms bndgmg the boron atoms (B-H-B). In each bridge there I are only two electrons for the - electron spin resonance ~ bonding orbital. a similar technique to nuclear : _ e1ectronegatlvlty . . . I
~gnetl~ r~~ance, b~ applield : electronegativity is the measure
cu:
~unp( ~ctron~m a dm~ - ~ e . e ra er an to ~ nu eI). I It IS a. powerful technique for:I . studymg free .. al radicals and tran- .smon-met complexes. ~ _ electron volt ; an electron volt (e V) is the en- I ergy acquired by an electron : when it passes through a poten- ~ tial difference of one volt. I 1 eV = 1.60 XI0 12 erg = 96 ~ kJ/mole. : I
of the relative attraction that atoms in a molecule have for h d . f I S are paIrs 0 e ectrons. . . Tables of the eIectronegatlVlty values of the elements have been prepared by Millikan by correlating ionisation potential and electron affinity data: EN = (IP. + EA) I 2 L.ater, Pauling used bond energies to prepare a scale in which he assigned fluorine, the most electronegative element, a value 4.
II ================-= InorglJnic Chemistry
II electronic bmul speam. I electronic con:ration oflin lltom The electronegativity values increase across each row of the periodic table because the nuclear positive charge is increasing and the atomic radius decreasing. Hence the closer the outer level of electrons is to the nucleus, the more difficult to attract electrons from the atom. The values decrease down each group, because the increasing atomic radius means a looser hold on outer level electrons
73
~
ments between which the bond ; is formed is greater than 1.9, : then the bond will likely be ionic. ~ Similarly, ifthe difference of the ~ electronegativities on the ; Pauling Scale of the elements : between which the bond is ~ formed is equal to or less than ; 1.9 the bond will be predomi~ nantly covalent. ~ • electronic band spectra
: molecular spectra occurring in ~ ultraviolet or visible regions of ; spectrUm, studied by absorpand the eftect of the increasing .. ch . ak: tion or emission. nuc1ear posltIVe arge 18 we - I ened by the screening effect of ~ • electronic configuration of the extra inner shells. an atom The uses of electronegativity ~ the electronic configuration of values are that they help to pre- ; an atom is the arrangement of diet the type of bonding to be : electrons in the atomic orbitals expected in a molecule, as well ~ about the nucleus of the atom. as the polarity of covalent mol- I The electrons of an atom travel ecules. The greater the differ- ~ in orbitals about the nucleus of ence in electronegativity values : the atom. Each orbitals is a volbetween the combining ele- ~ ume in space in which the elecments, the more likelihood of ; trons located in that orbital an ionic bond; the closer the : travel, giving rise to an electron values, the more likelihood of ~ cloud. The orbitals about an ~ atom have different energy leva covalent bond. For simple bonds, if the differ- ; els. The electrons associated ence of the electronegativities : with a given atom fill these oron the Pauling Scale of the ele- I
= ___= ___= ___= II
Inorganic Chemistry ______________________________
74
.. electronic publishing I electrophiles
II
bitals of that atom according to I and display on a computer systhe following rules. I tern. This hypertext document I is an example of electronic pubThe Aufbau Principle Electrons occupy the lowest : lishing. energy levels (i.e. sub-orbital) I • electronic structure of available when the atom is in the elements ground state. Hund's Rule ofMaximumMul- I the electrons of atoms are distiplicity I tributed over various levels in Where more than one orbital of ~ accordance with Pauli's excluequal energy is available, the : sio~ principle, H~d's ~e etc. electrons will occupy each or- I It IS represented III a SImple bital singly, before filling any ~ form as e.g., for Na, lS 2, 2S2 , orbital in pairs. : 2 p6,3S1• Pauli's Exclusion Principle ~ • electrons in the outer A pair of electrons in any sub- I shells orbital must have opposite ~ the electrons in the outer shells spins. Hence, no two electrons (i.e. in the outer atomic orbitin the same atom can have the I als) of the atom determine to a same four Quantum Numbers. I great extent the chemical propTo construct the electronic conerties of the elements. figuration of an atom from ~ these rules it is necessary to I • electrophiles know the energy levels of the ~ electrophiles are atoms or radidifferent orbitals in an atom, or : cals which are attracted to the at least the sequence of increas- I electron rich sites in a molecule. ing energy levels of the orbit- I Frequently, when an also electrophile attacks a carbon • electronic publishing atom in a molecule, it results in electronic publishing is the the displacement of another method of preparing and deliv- I atom, or group, from that carering text material for access I bon, giving rise to a substitution reaction.
" ================= Inorganic Chemistry
II
75
electrophilic I electroplating
*================ • electrophilic ~ from an electron rich carbon any chemical process in which ; atom during the course of the electron are acquired from or reaction. shared with other molecules or Common electrophiles include Ions. I the positively charged Meta-DiTecton I nitronium ion, N0 +, the posi2 ~H~JNO' NH~~mQprocucI ; tively charged chloronium ion, V ":sC\ y : CI+), and the positively charged j ~NOl • r _.".. """,, ~ methyl ion, CH3 + • N~HO _ H H :.;;:r~~~ ~ H'.,
".~>
9~:o
1¥~1IIodct!
0 0 ' 0,
- -ZCH~?~HO
i"""YHO o~~""" -
~
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~
InfJrgsnic Chemistry
electrophoretic effect
~ :~~~:o~~h~~:n:~~:g:; ~~ : opposite direction to that of a
~ particular ion. The ionic atmo~
• electrophilic addition ; reactions : electrophilic additions reactions ~ occur when the electrophile, ~ adds to the molecule without ; displa~ing any atom or group of ; atoms already present in the: I moIecule. : • electrophilic substitution reactions electrophilic substitution reactions are substitution reactions at electron rich carbon sites, where the substituting reagent is an electrophile and it displaces another atom, or radicals,
•
sphere tends to drag the ion with it. This is equivalent to an increase in viscosity of the solution which slows down the speed of an ion towards an dec trode. • electroplating I I · · th f e ectrop atmg IS e process 0 . the sun:ace 0 f one metal coatmg
~ object with a thin layer of anI
~
: ~ I
;
other metal. The applied metal is usually more expensive than the base metal that is coated. Electroplating is used for the protection of the metal which is coated, or to give a shining surface.
=================_11
76
eleetrtJrefining I element
II
===============* • electrorefining I • element electrorefrning is process of us- I chemists once defined an eleing electrolysis for the purifica- ment as a substance which tion of metals. For example, could not be broken down when copper rods are used as ~ chemically to give two or more electrodes in the hydrolysis of ; simpler substances. Thus, the a solution of copper sulphate, elements are the simplest if impure copper is used as an- chemical entities. However, ode, it dissolves and pure cop- I with the discovery of Radioacper is deposited on the cathode, tivity, this definition was not leaving the impurities behind in strictly correct. For example, solution. I the element radium ~vas found • electrovalent bond I to be constantly decomposing into different substances. (ionic bond) a binding force I Chemists once defmed an elebetween the ions in com- I ment as a substance in which all pounds in which the ions are the atoms were alike. However, formed by complete transfer I the discovery of Isotopes of electrons from one ele- I showed that not all atoms of an ment to another element or I element are alike. A new defiradical. For example, Na + CI nition was thus proposed: becomes N a + + CI-. The elec- I An element is defined as a subtrovalent bond arises from the I stance in which all of the atoms excess of the net attractive have the same atomic number force between the ions of op- (i.e. they contain the same numposite charge over the net re- ~ ber of protons in their nuclei). pulsive force between ions of ; Elements cannot be further sublike charge. The magnitude of : divided by chemical means. electrovalent interactions is of ~ Each element is unique and is the order 102 -10 3 kJ moP and I composed of atoms with a defielectrovalent compounds are I nite fixed atomic composition. generally solids with rigid lat- There are 92 naturally OCCUftices of closely packed ions. ring Element') on Earth. Further
II ================== Inorgallic Chemistry
I elevlJtion ofthe boiling point I elevlJtion ofthe boiling point
I I
77
*================
elements have been synthesisef ~ with the small letter (e.g. Hyin nuclear reactions. All known ; drogen has the symbol H and matter on Earth is composed of : Helium has the symbol He). different combination of these ~ Some elements can exist in difelements. The majority of ele- ~ ferent physical forms, which ments are classified as metals, ; differ in colour, hardness, meltthe remainder being non-met- : ing point, etc.. These different also ~ forms are called allotropes. For ; example, carbon can exist in Metals Iron, Copper, Tin, Manganese, : several different forms, includPotassium, Sodium ~ ing graphite and diamond Non-Metals ~ (which are pure forms of carCarbon, Hydrogen, Iodine, ; bon) and charcoal, coke and Phosphorus, Nitrogen, Sulphur : lampblack (which are impure I From the 18th Century, chem- : forms of carbon). Sulphur has ists began to discover new ele- ~ five different allotropes. ments. This discovery of ele- I • elevation of the boiling ments continued until 92 elepoint ments had been identified. : an elevation of the boiling point Chemists have been successful ~ of a solvent is observed when in synthesising new elements so ; substances are dissolved in it. that the total has now risen to ~ The amount by which the boil103. : ing point is elevated is proporEvery element has its own sym- I tional to the number of molbol, which represents one atom . 1 fth ; ecules of solute and indepenor sometlmes one mo e 0 at. d fth . . ent 0 elr nature. element. The symbols of the I Th 1 ul I . fboil kn ., e mo ec are evationo · h e1ements w h 1C were own ill I ing point is the elevation of the earlier days were derived from ~ boiling point produced when Latin names. Many of the ini: one gram-molecular weight of tialletters of the elements; oth~ the solute is dissolved in 100 ers have a second letter where ; gm. of solvent. there is more than one starting
i
Inorg4nic Chemistry
================= II
78
elutriRtion I empirical data "
==============~*
• elutriation : - enusslOn spectrum the method of separating a I a spectrum formed by a mamaterial into fractions ofvari- ~ terial which is heated, e.g., a ous sizes by permitting it to white hot wire, or byexcitasettle against upward moving I tion from an electric arc or stream of fluid, generally air or I electric discharge, e.g., as seen water. in gases in a discharge tube. • emanation A spectrum can be a continuI ous line or a band spectrum. an obsolete name for radon. I It is formed in the visible region or in the infrared or ul• emerald the green gem variety of beryl tra-violet region of e.m. : containing some Cr3+one of ~ waves. It is produced byexthe most highly prized gem- ; tra-nuclear electrons first bestones. The frnest specimen oc- ing excited by energy and becur in the Muzomines, Colom- I ing raised to a higher energy bia. Other occurrences include I level, and then falling back to the Ural Mountains, the a lower energy level and emitTransvaal in South Mrica, and ting energy in the form of e.m. Kallgunan in India. Emeralds waves. " .lIIIlDiIIII• • • • • can also be successfully synthe- I FSR=2GHz sized.
1--
• Emil Hermann Fischer a German chemist, Emil )1 !\ I II Hermann Fischer (1852-1919), _:_\__.,..L~_~_ produced synthetic sugars. His ~ Frequency [a ".J description of the chemistry of ; the carbohydrates and peptides - empirical data laid the foundations for the sci- I empirical data are the results that are obtained by experiment ence of biochemistry. or observation rather than from He received the Nobel prize I theory. 1902. &,0 00
0.2
04
0.6
OJ
1,0
II ================== Inorganic Chemistry
II
79
empiricalformula I end point
• empirical formula ~ optical antipode; optical isothe empirical formula ofa com- I mer. pound is the number of atoms ofeach element the are present I CHO CHO in a molecule of the compound HCOH HOCH in their simplest ratio.
I
• emulsification the process of dispersing one liquid in a second immiscible liquid; the largest group of emulsifying agents are soaps, detergents, and other compounds, whose basic structure ~s a paraffm chain terminating m a polar group. • emulsion breaking in an emulsion, the combined sedimentation and coalescence of emulsified drops of the dispersed phase so that they will settle out of the carrier liquid; can be accomplished mechanically (in settlers, cyclones, or centrifuges) with or without the aid of the droplets. • enantiomorph one of an isomeric pair of crystalline forms or compounds whose molecules are nonsuperimposable mirror images. Also known as enantiomer·,
lnorglJni& Chemistry
I
HOCH . ;
~
I
HCOH
I
CH20H
I I
HCOH
I
HOCH
I
CH20H
~ • enantiotropy ~ refers to the existence of differ; ent stable allotropes of an ele: ment at different temperatures· ~ sulphur, for example, exhibi~ ~ enantiotropy. The phase dia; gram ~or ~ onantiotropic ele~ ment IS havmg a point at ~hi~h : all the allotr~~s .can coeXist m ~ a stable equilibnum. At tem; pe~atures above or below this : pomt, one of the allotropes will ~ be more stable than the ; others(s).
~ • end point
: the end-point of a titration oc~ curs when the reaction is com~ plete, as shown by the change ; of colour of an indicator or by : other means.
================ II
""80"""""""""""""""""""""""""====""",,,,,* endothermiereRCtion I energy level /I
• endothermic reaction an endothermic reaction is a chemical reaction in which heat is absorbed.
I
• energy energy is the ability to do work, I and it is measured in joules. I • enermr change Energy is conveniently classi- I whenever a reaction occurs, it : is generally accompanied by a fied into two forms. ~ release or absorption of energy. Potential Energy which is the energy stored in a ; This gives the change in energy body or system as a conse- : i.e. the difference in the energy quence of its position, shape or ~ of products and reactants. state (this includes gravitational I • energy change in nuclear energy, electrical energy, ~ reaction nuclear energy and chemical : energy) and I it is given by the .Einstein's en. .' ergy mass equanon. E = mc2 Kinenc Energy I . . hi h . f' d . where E IS the energy eqwva~ c IS energy 0 monon an ; lent of mass m and c is the veIS usually defined as the work . l ' fligh 1 931 M that will be done by the work ~ OCltyO t. amu= ev. that will be done by the body ; • energy changes in chemical possessing the energy when it: reactions is brought to rest. I the energy changes in chemical I reactions is manifested in the • energy bands '. heat which is either absorbed or refers to continuous bands of I released during the course of energy arising from a series of ~ the reaction. close energy levels occurring mainly in metals where the va- ~ • energy level leney electrons form bonds with ; one of the discrete energies an increased number of: that an atom or molecule, for quantised energy levels. I instance, can have according to
II
================= Inorganic Chemistry
*
II enol-ketomutomerism I epaxyresins =====~=====81 quantum theory. Hence, in an ~ • enthalpy of sublimation atom there have been certain ; it is the enthalpy change that definite orbits that the elec- -~ accompanies the conversion of trons can be in, corresponding : one mole of solid directly into to definite electronic energy ~ gaseous state at a temperature levels of the atom. Similarly, ; below its melting point. a vibrating or rotating molI • entropy ecule can be having discrete ~ the entropy, S, is a measure of vibrational and rotational en: the fraction of the energy in a ergy levels. ~ system that is unavailable to do • enol-keto tautomerism ; work. the tautomeric migration of a : In a closed system, an incr~ase hydrogen atom from an adja- ~ in entropy is accompanied by a cent carbon atom to a carbonyl I decrease in energy available to group of a keto-compound to ~ dowork. produce the end form of the ; • enzymes compound, the reverse process : enzymes are proteins that acts of hydrogen atom migration ~ as a catalyst in biochemical realso occurs. I actions. Each enzyme is spe~ cific to a particular reaction or : group of similar reactions. ~ The names of most enzymes • enthalpy ; end in "-ase", which is added enthalpy, H, is the thermody~ to the names of the substrates namic property of a system de: on which they act. fined by the relationship I : • epoxy resins H = U + pV where H is the Enthalpy, ~ polyethers obtained by condenU is the Internal Energy of the ; sation ofepichlorophydrin with system, ~ polyols like bisphenol A, or by p its Pressure, and V its Vol- : epoxidation ofDiels-Alder adume. ~ ducts with peroxy compounds.
Inorganic Chemistry
================= /I
82
.. ClJuationofstat.e I equiptUencepoint
II
These are used as adhesives ~ - equilibrium protective coatings, etc. ~ equilibrium is a state in which _ equation of state ; a system has its energy distribthe equation of state is an equa- : uted in the statistically most tion that relates the pressure, p, ~ probable manner, in which the the volume, V., and the thermo- .I forces, influences, reactions, dynamic temperamre, T, and ; etc., balance each other out so the amount of substance, n. The : that there is no net change over simplest equation of state ~ time. A system at equilibrium (which applies only to ideal gas- I shows no tendency to alter over ~ time. A body is said to be in ses) is the ideal gas law PV = nRT : thermal equilibrium with its where R is the universal gas ~ surroundings if no net heat exconstant. ; change is taking place within it A more accurate equation of : or between it and its surround. I . state IS : : mgs. (p + k~(V - nb) = nRT ~ _ equilibrium constant where k IS a factor that reflects ; th uilib . num constant of a the decreased pressure on the: e e9 walls of the container as a re- ~ chemIcal reaction is the prodsult of the attractive forces be- ; uct of the molar concentrations tween particles and nb is the : of the products divided by the volume occupi~d by the par- ~ ~roductofthemolarconcentra tides themselves when the I nons of the reactants at a spepressure is infInitely high. ; cific temperature. In the Van der Waal's equation : _ equivalence point of state: ~ the equivalence point in a titra2 k = n ~ / V2' . I tion is the point at which reacwher~ a IS a constant. ThIS I tion is complete, as shown by equation more accurately . dica· f re- I the colour change ofthem b h aVlOur 0 real tor or by any other means. fl ects the e gases.
II ================= Inorganic Chemistry
83 .~=====~
• equivalent electrons electron in an atom which have the same principal and orbital uantum numbers but not ~ecessarily the same'inagnetic orbital and magnetic spin quantum numbers. • equivalent weight the equivalent weight of an element or compound is the mass that combines with or displaces one gram of hydrogen (or eight grams of ~xyg~n or 35.5 grams of chlonne) m a chemical reaction. The eq~valent weight represents the combining power of the substance. For an ~lement ~t is the relative atOmIC mass dlvided by the valency. For a compound it depends on the reaction considered. . • erbium symbol Er, a soft silvery metallic element belonging to the lanthanides; a. n. 68; r.a.m. 167.26; r.d. 9.066 (20°C); m.p. 1529°C; b.p. 2868°C. It occurs in apalite, gadolinite, and xenotine from certain sources. There are six natural isotopes, which are stable, and Imn;gllnic Chemistry
~ I
~
:
~
I
~
~ I I
; : ~ I
~
: ~ I
~
:
twelve artificial isotope~ are known. It has been used m alloys for nuclear technology ~s it is a neutron absorber; It IS being ~nvestigated for other potentIal uses. • eriochrome black T indicator eriochrome Black T is the indicator used in titrations. • essential amino acid refers to an amino acid that an organism is unable to synthesize in sufficient quantities. It must therefore be present in the diet. In man, the essential amino acids are arginine, histidine, lysine, threonine, methionine, isoleucine, leucine, valine, phenylanine, and tryp_ tophan.
I
: • esters .~ esters , RCOO~, are organic I compounds of carbon, hydro~ gen and oxygen, that are the : products formed by the con~ densation reaction between ; organic acids and alcohols. : The ester functional group, ~ C=O.O-, is contained within ~ the molecule.
================ II
84 ~====~=~
•
ethtmid I ethylme oxUIe
II
• ethanal ~ heating ethylene chloropethanal, CH3 .CHO, is the sec- ; hydrin with Ca(OH)2 or ond member of the aldehyde ~ NaOH solution; or by the diseries of compounds. : rect oxidation of ethene at ~ 2SO-300°C using a silver cata; lyst. It forms an explosive , Aldehydes : mixture with air. Reacts with Nomenclature' ~ water in the presence of 1/ ~ sulphuric acid to give ethylene CH-C-H 3 ; glycol and polyethylene glyetbaoaI : cols; with alcohols and phenols (acetaldehyde) I . . . to give ethers of glycol; and • eth ane .I WI'th hYd rochl' . . ' onc aCI'd to gIve ethane, CH3CH3, IS the se~ond ~ ethylene chlorophydrin. It remember of the alkane senes of : acts with many primary and hydrocarbons. ~ secondary amines to give etha• ethanolamines ; nolamines; with organic acids ethanolamines form soaps; to give monoeste~s of ~thyl with higher fatty acids, which : ene ~lycol, ~d w~th aCId a~ are excellent emulsifying ~ hydndes to give dlesters. It IS agents and are used exten- ; reduced by ~ydrogen to ethasively in the manufacture of ; nol, and IS cO~lVerted to shaving creams and lotions, : ethanal by heatmg at 200insecticide sprays, furniture ~ 3~0°C in th~ p~esence o~ alU,. polishes, and dry-cleaning; mma. Its. prI?clpal use IS for preparation. : PolymensatlOn to 1, 2-ep~ oxide polymers. It is also used . • ethylene oXlde ' . d" h I as an Interme late m t e 2-epoxyethane, oxirane CHr : manufacture of ethylene glyCH20. Colourle~s g~s with a ~ col, polyethylene glycols, glysweet odour which IS some- I col ethers ethano-lamines and what lachrymatory; b.p. ~ similarco'mpounds. 10.SoC. Manufactured by :
o
II ================= 11JOf'8.nu Cbemistry
II
85
eucalyptus oil I evRporation
_ eucalyptus oil
.
oil distilled from the leaves of different species of Eucalyptus. It is used as an antiseptic and as a prophylactic for cold and influenza.
I
--
. a.- ......
.
I
_ europium oxide
Eu2 0 3 , a white powder, insoluble in water; used in redand infrared-sensitive phospho-
I
.::::r.::-
I
fUS.
: oxygen by night, and increased ~ synthesis of toxic compounds I associated with algae. Further, ~ the organic compounds : synthesised by algae give rise to ~ chloroorganics when these wa; ters are extracted and dis in: fected with chlorine for use as ~ drinking water.
- eutectic mixture a solid solution having two or more substances and;having the lowest freezing point of any prn;siblc mixture of these components. The minimum freezing point for a set of components is termed as the eutectic I point. : ~ _ eutrophication eutrophication is the enrich- ; ment of bodies of water by nu- : trients which lead to the en- ~
hanced growth of algae. High levels of algae in natural waters give rise to undesirable consequence, including increased turbidity due to the suspended solids, reduced levels of dissolved
Imn;gRnic Chemistry
...-._-
I
~
: ~
; :
~
•
- evaporatlon evaporation is the change of state of a liquid into a vapour at a temperature below the boiling point of the liquid. Evaporation occurs at the surface of a liquid, some of those molecules with the highest kinetic energies escaping into the gas phase. The result is a fall in the average kinetic energy ofthe molecules of the liquid and con-
================ II
86 ~~~~~~~~*
sequentlya fall in its tempera- ~ • exclusion principle ture. ~ the principle, enunciated by • even-even nucleus ; Pauli in 1925, that no two eleca nucleus having an even num- : trons in an atom could have an her of neutrons and an even ~ identical set of four quantum number of protons. I numbers. • excitation I • exothermic reactions refers to the process of produc- ; exothermic reactions are chemiing an excited state of an atom, ~ cal reaction in which heat is molecule, etc . evolved. • excitation el)cr;gy refers to the energy which is I required to change an atom, I molecule, etc. from one quan- : . h a:I tum state toa state WIt higher energy. ·The excitation ~ energy (sometimes called exci- ; tation potential) refers to the : diffi . erence between two energy .~ IeveIs 0 f the system. :I • excitation ~ excitation is a process in which ; a nucleus, electrons, atom, ion, I: or molecule acquires energy : that raises it to a higher quan- I tum state (i.e; excited state) than : that of its ground state. The dif- ~ ference between the energy in I the ground state and that in the ~ excited state is called the excita- : I tion energy.
• experiment . .IS a proced ure an expenment used tocheck thevalidityof an assumption or hypothesis, or to measure some characteristic of a substance. • explosion .
.
a cheffilcal.rea~on or ch.ange of stat~ which IS effected ill an e~eedingly short. space of time WIth the generatIon of a high temperatu~e and generally a large quantIty of gas.
• explosives modern explosives are or- I ganic_ compounds of carbon, hydrogen, nitrogen and oxygen, whose the molecules contain sufficient oxygen to con- I vert the carbon and hydrogen in the molecule to carbon dioxide and water and to liber- I ate the nitrogen as a gas. The decomposition ofexplosives is ~ • factors affecting the rates extremely rapid and highly I of chemical reactions ~ the factors affecting the rates of exothermic. : chemical reactions include tem• extinction coefficient . f :I perature, concentranon 0 reacthe reciprocal of the thickness ~ tants, the presence of catalysts, of an absorber necessary to re- ; etc.. duce the light intensity to 9/10 ~ • Fahrenheit scale of temof its initial value. perature • face-centred cubic crystal ~ the Fahrenheit scale of tempera(fc.c.), a crystal structure in ; ture, named after G.D. Fahrenwhich the unit cell has atoms, : heit (1686-1736) who invented ions, or molecules at each cor- ~ it, has the temperature of boilner and each face ce~tre of a ~ ing water as 212 degre~s ~d cube (also called CUbl~ cl~se- I the temperature of melnng l~e packed). It has a coordinano? : as 32 degrees. The FahrenheIt number of 12. The structure IS ~ scale is no longer in scientific close-packed and made up of ~ use. layers of atoms in whic? each ; To convert from the Fahrenheit atom is surrounded by SIX oth- : scale to the Celsius scale the ers arranged hexagonally. O:>p- ~ formula is per and Aluminium have face- ; deg C = 5 ( deg F - 32) /9. centred cubic structures. . lnorzTanic Chemistry
==============___
11
88
• FRjtm~smethotll F.,.."sCDMtilnt
II
- Fajan's method ~ sion fragments iodine-131 and the titration of CI- with Ag+ ; strontium-90_ Both can be using fluorescein as an adsorp- ~ taken up by grazing animals tion indicator. At the end point, : and passed on to human poputhe colour of the precipitate is ~ lations in milk, milk products, ; and meat. Iodine 131 accumured. : lates in the thyroid gland and . 'rut - FaJan s es I ' . ·· f' tak - stromum-90 accumulates In the poIansatIon 0 aruon. es; bones. place w~en two OppOSItely ~ 2. chemical fall-out. Hazardous charged Ions approach t d · feach ' ._ chemicals dis ch arged'moan th Th laris ? er. e po atIo~ 0 aruon I subsequently released from the ~ favoured by. large SIZe of the ~ atmosphere, especially by fac~ons, small catIon and large an- : tory chimne s. lOn, nature of the solvent and I y nature of the cation. ~ - family £0_11 t : a group of elements whose -1.iU10U I ' a l propertles, . _.. ch effilC such as ~. radioactIve partIcles depos- ; valence, solubility of salts, and lted from the atmosphere eIther : behaviour toward reagents are from a nuclear e~plosion or ~ similar. ' from a nuclear aCCIdent. Local ; fall-out, within 250 km of an : - Faraday's constant explosion, falls within a few ~ the Faraday Constant, F, is the hours of the explosion. Tropo- ; electric charge carried by one spheric fall-out consists of fme ' : mole of electrons or singly particles deposited all round the ~ ionised ions (i.e. the product of earth in the approximate lati- I Avogadro constant and the tude of the explosion within ~ charge on an electron or ion, about one week. Stratospheric : disregarding sign). fall-out may fall any where on ~ It has the value 9.648670 X 1()4 earth over a period of years. ; coulombs per mole. The most dangerous radioactive : This number of coulombs is isotopes in fall-out are the fis- ~ sometimes treated as a unit of
II ================ I'""1Jllnie Chmfimy
II F.nularsIIIws ofelearolysis Ifotty ac: electric charge called the Faraday. _ Faraday's laws of electrolysis faraday's Laws of Electrolysis govern the electrolysis of aqueous solutions and state Faraday's First Laws of Electrolysis The mass of a substance liberated at each electrode is directly proportional to the quantity of electricity which passes (i.e. to the current strength and to the time), and Faraday's Second Laws ofElectrolysis The masses of the elements liberated by the same quantity of electricity are directly proportional to their chemical equivalents. _ fast chemical reaction refers to a reaction with a halflife of millisecond or less; such reactions proceed so rapidly that special experimental techniques are required to observe their rate. _ fat
89
~ normal body temperatures. I
~ :
~ ; :
~ ~
; :
~
~ ; : ~ I
; : ~
; : I
Fats occur widely in plants and animals as a means of storing food energy, having twice the calorific value of carbohydrates. In mammals, fat is deposited in a layer beneath the skin (subcutaneous fat) and deep within the body as a specialised adipose tissue. Fats derived from plants and fish gen:rally have a greater proportIOn of unsaturated fatty acids than those from mammals. Their melting points thus tend to be lower, causing a softer consistency at room temperatures. Highly unsaturat~d fats are liquid at room temperatures and are therefore more properly called oils.
: - fatty acids I . : fatty aCIds, RCOOH, are a ho~ mologous series of organic ac; ids, where R is an alkyl radi: cal. The higher members of ~ this series of acids occur in ~ nature in the combined form ; of esters of glycerol, and
a mixture of lipids, chiefly : hence all of this family are ~. called fatty acids. triglycerides, that is solid at lnorgllnic Chemistry
================= II
90
fodstock I flnnium "
~~~~=====* I
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• feedstock the Feedstock for the manufacture of petroleum products and petrochemicals is crude oil extracted from known reserves. .• feldspars a group of aluminosilicates with framework structures with AI or Si in tetrahedral co-ordination. The most common constituents of igneous rocks. Subdivided into two groups depending on the detailed structural types. Used in the ceramic and enamelling industries. • fermentation of carbohydrates the fermentation of carbohydrates is a form of anaerobic respiration occurring in certain microorganism (e.g. yeasts), comprises a series of biochemical reactions by which sugars (i.e. saccha-
rides), including glucose and sucrose, are converted to ethanol and carbon dioxide. • fermi a unit of length equal to 10. 15 metre. It was formerly used in atomic and nuclear physics . fermi level refers to the energy level in a solid at which the probability of finding an electron is 1/2. The Fermi level in conductors is situated in the conduction band, in insulators it is situated in the valence band, and in semiconductors it falls in the gap between the conduction band and the valence band.
I • I
I
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fermium symbol Fm, a radioactive metallic transuranic element belonging to the actinoids; a.n . I 100; mass number of the most stable isotope 257 (half-life 10 I days). Ten isotopes are known. I The element was first identiI fied by A. Ghiorso and associates in debris from the first ~ hydrogen-bomb explosion in ; 1952. : I •
I
I
================ IntI'1JlJnic Chemistry
11 __
II formte lferrouscompounds
91
~ _ ferrous ammonium sul- ferrate a multiple iron oxide with an- ; phate other oxide, for example, : Fe(S04)· (NH)zS04· 6H zO , ~ light-green, water-soluble crysN~Fe°4· I tals· used in medicine, analyti- ferric ~ cal ~hemistry, and metallurgy. the term for a compound of : Also known as iron ammonium trivalent iron, for example, fer- ~ sulphate; Mohr's salt. ~ _ ferrous arsenate ric bromide, FeBr3·
- ferric compound ferric compound are compounds of iron in its + 3 oxidation state. Examples include iron (ill) chloride, Fe~, which was previously called ferric chlo-
~ Fe3(As04)3.6HzO, water-in; soluble, toxic green amorphous : powder, soluble in acids; used ~ in medicine and as an insecti; cide. Also known as iron arsen. ate.
ride. _ ferromolybdenum alloy of Fe and Mo (60-65%) used to introduce Mo into alloy steels and special cast irons. Obtained by reducing MoS z with Fe and C in an electric furnace.
: _ ferrous carbonate
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: FeC0 3 , green rhombohedral ~ crystals that are soluble in car; bonated water and decompose :I when heated; used in medicine. : - ferrous chloride ~ FeCl2"4Hz0, green, monoclinic ~ crystals, soluble in water; used ; as a mordant in dyeing, for sew: age treatment, in metallurgy, ~ and in pharmaceutical preparaI tions. Also known as iron chlo~ ride; iron dichloride.
- ferrosilicon iron silicide, FeSi, obtained by reducing a silicon-containing iron-ore in an electric furnace; used in the manufacture of steels and to reduce the ~ - ferrous compounds amount of iron carbide in cast : ferrous compounds are comiron. ~ pounds of iron in its + 2 oxidaInorganic Chemistry
================
II
ftrrous hydrtMtle Ifilter
92
II
tion state. Examples include ~ hydrogen sulphide in ceramics iron (II) chloride, FeC12, which ; manufacture. Also known as was previously called ferrous : iron sulphide. chloride. ~ • fertilisers I
• ferrous hydroxide although any substance which Fe(OH)2' a white, water-in- ~ increases production when soluble, gelatinous solid that ; added to the soil could be called turns reddish-brown as it : afertiliser,usualIyinpracticeby I fertilisers are meant comoxidises to ferric hydroxide. • ferrous oxide ~ pounds containing N, P or K. ; Ammonium sulphate is the FeO, a black powder, soluble in most important nitrogenous water, melting at 1419<>C. Also I fertiliser; sodium nitrate, amknown as black iron oxide; iron I monium nitrate, ammonia and monoxide. urea are also used. A mixture • ferrous sulphate of ammonium nitrate and calFeS04.~O, blue-green, wa- I cium carbonate is sold under ter-soluble, monoclinic crystals; I the name of Nitro-chalk. The used as a mordant in dyeing : most important fertilisers conwool, in the manufacture ofink, ~ taining phosphorus are the suand as a disinfectant. Also I perphosphates which are minknown as ferricsulphates; green eral tricalcium phosphates rencopper as; green vitriol; iron dered more soluble by treatsulphate. I ment with sulphuric acid and I ammonium phosphate. Many • ferrous sulphate mixed fertilisers are now sold, ferrous sulphate, Fe(II)SO4' is I containing various proportions the salt formed when iron is I of nitrogen, phosphorus and dissolved in sulphuric acid. I potassium. • ferrous sulphide ~ • filter FeS, black crystals, insoluble in : a ftlter is a device for separatwater, soluble in acids, melting I ing solids from liquids or an point 1195°C; used to generate: II
================= I1tIJ11!4ni& Chemistry
II filter pump Ifluori1l4tion insoluble substance from a soluble one. The simplest laboratory fIlter for liquids is a fluted glass funnel in which a cone of special paper, known as fIlter paper, is placed. The liquid to be fIltered is passed through the paper fIlter, whereupon the insoluble solids are retained on the fIlter. Grouch crucibles, which are special containers with a porous base of sintered glass, are also used as fIlters.
93 ~ I
• first law of thermodynamlCS
: the First Law of Thermody~ namics states that in a system ~ of constant mass, energy can ; neither be created nor de: stroyed, but may be converted ~ from one form to another.
~ • flocculation ~ flocculation is a process of ag; gregating into larger clumps. : Finely divided precipitates, ~ where the particles are small I enough to pass through the • filter pump ~ pores in a futer, need to undergo a fIlter pump is a simple labo- : flocculation to form larger parratory vacuum pump in which ~ ticles before fIltration. air is removed from a system ~ • fluorescence by a jet ofwater forced through ; fluorescence is emission oflight a narrow nozzle. The lowest pressure possible is the vapour ~ from compounds which have : been illuminated, due to the pressure or water. ~ return of the compound from • filtration ; an excited state to the ground fIltration is a method of sepa- : state. I rating a solid from a liquid or : • fluorides an insoluble substance from a soluble one. The mixture is ~ fluorides are the salts ofhydrofI luoric acid. poured through a fIlter; the liquid that goes through the fIlter I • fluorination and is called the fIltrate, and the ; fluorination is a chemical reacsolid that remains on the fIlter : tion in which a fluorine atom is is called the residue';:. ~ introduced into a molecule.
lnorglJni& Chemistry
================= II
94
fluorocarbons
Ifossil foeU /I
• fluorocarbons ~ Fluorspar is used chiefly as a fluorocarbons are compounds ; flux material in the smelting of obtained by replacing some or iron and steel. It is also used as all the hydrogen atoms of hy- a source of fluorine and hydrofdrocarbons with fluorine at- I luoric acid and in the manufacoms. Their high stability to tem- I ture of ceramics and in the opperature makes them suitable tical-glass industry. for a variety of uses, including • foam aerosol propellants, oils, poly- I foam is a dispersion of bubbles mers, etc.. I of gas in a liquid. They are often known as freons. Their use in aerosols is one ~ • folic acid cause of the depletion of zone ; folic acid is a member of the layer. ~ vitamin B group of vitamins . • fluorspar fluorite or fluorspar (i.e. calcium fluoride, CaP 2) is a mineral that occurs in Derbyshire, crystallised in cubes or octahedral or in compact masses like marble. It is also called Derbyshire spar, or Blue Jhon, when the crystals are coloured blue or purple. The colourless transparent crystals show a bluish tinge when light falls on them, and this property is called fluorescence. Fluorspar was described by Agricola in 1530AD, as fluor (from the Latin fluo, I flow), since it melts at a red heat, approximately 1330 degC.
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; • formula : a formula is a way of represent~ ing a chemical compound using I symbols for the atoms present. Subscripts are used to denote I the numbers of each type of I atom.
~ • fossil fuels I I
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the fossil fuels (i.e. coal, oil, natural gas, etc.) derive from the decay of vegetable matter and are used by man as a source of energy.
II ================= Inorganic Chemistry
95
- fractional crystallisation fractional crystallisation is a method of separating a mixture of soluble solids by dissolving them in a suitable hot solvent and then lowering the temperature slowly. The least soluble component will crystallise out frrst, leaving the other components in solution. By controlling the temperature, it is sometimes possible to remove each component in turn.
~ tional distillation is used to ; separate liquids with close boil: ing points. I
:I - fractionating column : a fractionating column is added ~ before the condenser in frac; tional distillation and contains : glass rings or balls which pro~ vide a large surface area for con~ densation and re-evaporation. I ....ac:tia18ling
cdurmwilh bubble cops
- fractional distillation fractional distillation is similar to distillation, but uses an additional piece of apparatus called a fractionating column. A fractionating column ~ntains glass
rings or balls which provide a large surface area for condensation and re-evaporation. The vapour of the liquid with the lowest boiling point reaches the top of the column first. Frac-
Inora,,,,it; Chemistry
L..~~->--diesel
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~ - Francois Auguste-Victor ; Grignard : a French chemist, Francois ~ Auguste-Victor Grignard I (1871-1935) discovered in ; 1900 a series of organic com: pounds now known as the ~ Grignard Reagents. These re; agents have found applications : as some of the most versatile ~ reagents in organic chemistry. I Members of this class contain a ; hydrocarbon radical, magne-
==========~===== II
~96! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !F:~';h process 1}We nulictU chtM ~ II chemical reaction or for longer periods under special conditions. Examples of free radi,:al formaI tion include the case where a - Frasch process chlorine molecule is dissociated the Frasch Process is a method' ~ by a photon of light into two of obtaining sulphur from un- ; chlorine radicals (i.e. unpaired dergrounddepositsusingatube I chlorine atoms), which are consisting of three concentric highly reactive sium, and a halogen such as chlorine. He received the Nobel Prize for chemi$try in 1912.
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pipes. Superheated steam is passed down the outer pipe to melt the sulphur, which is then forced up through the intermediate pipe by compressed air from the inner tube. The steam in the outer casing keeps the sulphur molten in the pipe. _ free radical a free radical is an atom,or , group ofatoms, which normally exist only in combination with other atoms, but which may exist independently for short periods during the coUrse of a
II
Cl2 (light) = = > 2 CI* These radicals are then available to initiate and propagate other chemical reactions.
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: _ free radical chain reaction I the free radical chain reaction I is the mechanism of many selfsustaining chemical reactions. Chain reactions are exothermic I (i.e. they release large amounts I of heat), but they may require a high temperature, or other special conditions, to start I them. In the case of combustion, the initial heat is required for the bond breaki.D.g which is I required to produce the free I radicals, and initiate the chain : reaction. However, when this ~ initiation has been achieved, the ; chain reaction can proceed with the release of energy in suffiI
================_ ltun'lJllnic Chemistry
frwudrying I Friedel-cmfts~
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cient quantity to' continue to ~ molecule of halogen hydracid, ; usually hydrogen chloride or propagate the reaction. : hydrogen bromide from the I • freeze drying : complex formed between the freeze drying is the process used I molecule of an aromatic comin dehydrating food, blood ; pound and another halo-complasma and other heat sensitive : pound which mayor may not substances. The product is deep ~ be aromatic in character. This frozen and the ice trapped in it ; reaction is effected with the aid removed by reducing the pres: of anhydrous aluminum chlosure and causing it to sublime. ~ ride as a catalyst. The water vapour is then reI The mechanism is an electromoved, leaving an undamaged ; philic substitution. The hydrodry product. : gen atom which is eliminated • freezing ~ must come from the nucleus of freezing is the process by which I an aromatic body, and the haloa liquid changes from liquid to ~ gen atom may be provided eisolid. It is the opposite of melt- : ther by an aliphatic halogen ing. ~ compound or by an aromatic • freezing point ; compound in which the halogen : atom is present in a side chain the freezing point ofa substance · ~ (i.e. not in the nucleus). is the temperature at which it ~ For example, when benzene is changes state from a liquid to a ; heated with methyl chloride or solid. The melting point and the : bromide in the presence of the freezing point are identical. ~ catalyst anhydrous aluminum • Friedel-Crafts reaction ; chloride, toluene, CH3,C6HS the Friedel-Crafts Reaction, : (i.e. methyl benzene) is obnamed after the French chem- ~ tained. The catalyst acts as an ist Charles Friedel (1832-99) ~ electron acceptor for a lone pair and the US chemist James M ; on the chlorine atom. This Craft (1839-1917), consists es- : polarises the haloalkane or acyl I sentially in the elimination of a : group.
I
It is worth noting that the ~ - fuel oil Friedel-Crafts reaction has no i fuel oil is a higher boiling fracparallel in aliphatic chemistry. ~ tion from the distillation of : crude oil. - Fritz Haber I a German chemist, Fritz Haber : - functional group (1868-1934) was the inventor ~ a functional group is an atom of the Haber Process. He was I or a group of atoms that defines awarded the Nobel Prize in ~ the characteristic properties of Chemistry in 1918AD for this : a particular family of comwork which led to the Synthe- ~ pounds .. Org~c compounds sified mto a num~r of sis ofAmmonia from hydrogen, ~ ~e and nitrogen. i distmct homologo~ senes of His study of the combustion of : com~unds, accor~ to the hydrocarbons led to the com- ~ fun~onal groups which they bustion of hydrocarbon led to ~ contam. ·al" C kin . For example, any compound the commercl rac g or I .. th bo 1 fun f tural· contammg e car xy c. naldistilla· . FraCt10 non 0 na . . nal COOH . .• I no group, , beloogs oil (petroleum) mto Its compo- : to the carboxylic acid homolonents.. ~ gous series and acidic properIn ElectrocheffilStry, he was.the ~ ties are always associated with ~t to demons~te that oXlda- i the carboxylic acids due to the non and redUctlon take place at : presence of an ionisable hydrothe electrodes, from this he de- ~ gen atom.. veloped a general electrochemi- i fundam " tal am· 1 .. en p ces caltheory. I . I the fundamental particles--are - fuel cells ~ the subatomic particles in thefuel cells are electrochemical : atomic particles, from which cells in which the chemical en- ~ the atoms of all elements are ergy"of a fuel is'converted di- ~ made. T~e p~otons and neui trons eXIsts m the nucleus, rectly.into electrical energy. : which is the central core of the
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99
atom, and the electrons travels in the orbitals about the nucleus of the atom. These atomic particles (i.e. protons, and neutrons) are themselves composed of the sub-atomic particles (i.e. the Quarks and Leptons), which are also called the fundamental particles.
~
tric energy. When the electro; chemical cell is used as a source : of electrical energy, (i.e. if it :• converts the free energy of a ~ physical or chemical change into ; electrical free energy), it is : called a Galvanit Cell. •
: - gamma-ray ~ a gamma-Ray is a photon of • electromagnetic radiation emit- furan furan, C 4H 40, is a colourless ~ ted from the excited (i.e. high liquid. : energy state) nucleus, so that It has a five membered ring ~ the latter goes to a more stable consisting of four methylene ; lower energy state. groups, C~, groups and one .-gas oxygen atom. ~ a gas is one of the states in _ galvanic cells : which matter can exist. A gas galvanic cells are electrochemi- ~ has neither a fixed volume, or a cal cells in which the chemical ; definite shape. energy ofthe constituents ofthe ; - gas discharge tubes cell are converted into electri~ gas discharge tubes were used cal energy. Electrochemical cells : about 1750AD by William ~ Watson in England, who ; showed that the flow of charge Gas Discharge Tube
I
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are the assembly of electrodes and solutions ofelectrolytes that result in the production of elec- •
lnoral" ' " Chmlinry
================
II
8111~1~11
100 through a gas in sealed con- ~ tainer increases as the pressure ; is lowered. As the pressure in : ~ the container is reduced below ~ that of the atmosphere, conduc- ~ tivity increases until, at a pres- ; sure of about 0.001 atmo- : sphere, gases become fairly ~ good conductors. ; Two things can be observed ~ about electric conduction in a : gas at low pressure. I A COnsl·derable' potenn·al diffcer- :I . . ence (1.e. voltage) must be ap-· . I plied to the gas before any cur- : rent can be detected. The exact I value of the minimum voltage ~ depends on the gas used and on : the design of the apparatus. ~ As charge flows through the ; gas, the gas glows with a colour : which depends on the gas used. ~ This process is often called gas I discharge, and the apparatus used is called a gas discharge tube. - gas mixtures gas mixtures result from the property that all gases expand to fill the volume into which they are introduced (i.e. they do not have a fIxed shape). Provided that the individual gases
introduced into a given volwne do not react with each other, that volume becomes a homogeneous mixture of the gases. The physical properties of a mixture of gases, which do not react with each other, are described by Dalton's Law of Partial Pressures and by Graham's Law. _ gas thermometer . .
a gas thermometer IS a deVIce . . for measunng temperature m ··ch tbeworking flill·d·IS a gas. WID
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: - gasahol I gasahol is the mixture of petroIleum spirits with ethanol derived from the fermentation of
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to carbon axis in the case of ; double bonds, which is pre: vented by the pi bond (i.e. the I : second bond of the double ~ bond). The geometry of the ; molecule is determined by the : n~e of the s bonds (sigma ~ bOncJs) between the two carbon ; atoms and the four attached ~ groups (i.e. sp2 hybrid.bonds). : Thus, the two carbons linked by I the double bond and the fIrst • Gay-Iussac's law ; atom of each ofthe four groups Gay-Lussac's 's Law states that : attached to these atoms are plawhen gases combine in chemical I .. od . nar. d'ffi d reactlons to gIve gaseous p1'l - ' Th . fthe vo1urnes 0 f I : .us, 1 erent compoun s ucts, the ratio 0 . . gasesto thatofthe I whichf contam the. same numthereacnng : ber 0 each constituent atoms . . l '
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~lO~2! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !GerINml! ! ! ! ! ! ! ! ! ! ! J:Jorua#t! ! ! ! . I GrrIhtIm~s -tf8M«"" ~ atom or groups of atoms attached to that bond. If either carbon carries two identical atom or groups of atoms, geometric isomerism cannot exist. Geometric isomers are possible only if a certain order exists among the atom or groups of atoms attached to that bond. If either carbon carries two identical atom or groups of atoms, geometric isomerism cat,Ulot exist. • Gerhard Domagk a German pathologist Gerhard Domagk (1895-1964), the antibacterial sulphonamide drugs. He found in 1932 that coal..;tar dye called Prontosil red contains
II
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chemicals with powerful antii bacterial properties. : Sulphanamide drugs, used be~ fore antibiotics were discovered ~ to treat a wide range of condii tions, including pneumonia and : septic wounds. Domagk was ~ awarded the 1939 Nobel Prize I for Physiology and medicine ~ (because of the war had to wait : until 1947 to claim his prize). ~ • Germain Henri Hess ~ a Swiss chemist and doctor, ; Germain Henri Hess (1892: 1850), was born in Geneva and ~ was brought to Russia in ~ 1805AD. He is remembered ; for his work in Thermochem: istry and his Law of Heat of ~ Summation. ~ • Gooch crucible ~ a Gooch crucible is a porcelain i dish with a perforated base : over which a layer of asbestos ~ is placed, used for fIltration in ~ gravimetric analysis. I • Graham's law of gaseous : diffusion I : Graham's Law of Gaseous DiEI fusion states that the diffusion I rate of a gas is inversely pro-
II grtIvimetrie antdysis I Grignartl reRfJmts
103
*==========~
portion:u to the square root of Its den~lty: .., The ~rmClpal descnbed m this law IS used in the diffusion method of separating isotopes. • gravimetric analysis gravimetric analysis is the quantitative analysis of materials that depends on weighing. For example, the amount of silver in a solution of silver salts could be measured by adding excess hydrochloric acid to precipitate s~v~r chloride, fdtering the preclpltate, washing, drying and weighing. • greenhouse effect the greenhouse effect is the increase in the temperature of the earth's atmosphere caused by the presence of certain gases. Carbon dioxide plays an irpportant role in warming the earth by trapping the sun's heat. For millions of years the carbon cycle maintained a balance between the process that add and those that take away carbon from the air. . In modern times, people have upset this balance by burning vast amounts of fossil fuels, and
lnoraanic Chemistry
~ so releasing excess carbon diox~ ide into the atmosphere. A lot
. of tropical rainforest has been ~ destroyed, which in turn has ~ reduced the amount of carbon ; dioxide used up by green plants : during photosynthesis. This has ~ resulted in an increase in the ~ ~oncentration ofcarbon dioxide I m the atmosphere. : As the concentration of carbon ~ dioxide in the air increases, ~ more heat energy is trapped, ; and less is radiated out of the : atmosphere. Thus, the average ~ temperature of the earth's sur~ face gradually increases. ; ~ ~ : ~
; : ~ ; ~ : ~ ; ~ :
• Grignard reagents the Grignard Reagents, named after their Fre.nch discoverer, are very reactive compounds and are used in the synthesis of hydr~car?ons, alcohols, carboxylic aClds and aldehydes. For example, when a solution of a suitable alkyl halide in dry die~yl ethel~ is added to magneSlum turmngs h~at is evolved ~d the magneSIum gradually dIssolves i~ the boiling ether. Th~ resultmg solution is the Gngnard Reagent, which con-
================ II
"",l04"""",,=======~*grouPI elements IgroupID dementi
II
tains a highly reactive polar co- ~ • group II elements valent carbon to magnesium ; the elements in this group have . th· bond. I: tw0 e1ectrons m elf outer e1ec• group I elements : tronic shell. Thus, each element the elements in this group ~ in this group has a tendency to have one electron in their I lose two electron, to form a outer electronic shell. Thus, ~ do~bly charged positive ion, each element in this group has ; which has ~e stable electro~ic a tendency to lose a single elec- : co~figur~tlOn of ItS tron, to form a singly charged ~ neIgh?ourmg ~0t:>el Gas elepositive ion which has the . ment m the penodic table. stable electro;Uc configuration ~ The e.lements in. the group are of its neighbouring Nobel Gas ~ chemIcally reactive. element in the periodic table. ; Sub-Group II A: The Alkaline The elements in the group are ; Earth ~etals . chemically reactive. : ~erylhum, ~agnesn~m, CalThe group is divided into two I c~um, StrontIum, Banum, Ra: dium I . . sub-groups. Sub-Group I A : The Alkali : Sub-Group IIB : TranSItIon ~ ~etal Elements Metals Lithium, Sodium, Potassium, ~ Zmc, Cadmium, Mercury Rubidium, Caesium, Fran- ; • group III elements cium : the elements in this group have Sub-Group I B : Transition ~ three electrons in their outer; most electronic shell. The elecMetal Elements Copper, Silver, Gold ; tronic configurations ofthe n th Hydrogen is included in this: orbitals (i.e. outer-most orbitgroup because it has a single ~ als) are ns 2 np!. Thus, each elelectron in its outer electronic ; ement in this group has a tenshell. However, hydrogen has ; dency to l.ose three electron, to ~one of the metallic proper- : ~orm a Iply charged positive tIes of the alkali metals. I lon, whICh has the stable electronic configuration of its near-
:r
II ================ lnorgllni& Chemistry
II8"f1UP IV elements l8"f1Upnumber •
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est neighbouring Nobel Gas el- ~ These are the inner transition ement in the periodic table. ; elements, and are also called the The elements in the group are : Actinides. ~ Sub-Group IlIb : Main Group chemically reactive. Sub-Group IlIa : Transition ~ Elements Metal Elements ; Boron, Aluminium, Gallium, Scandium, yttrium, Lanthanum : Indium, Thallium , The following elements also ~ • group IV elements •• have the same electronic con- 1 I than (. 42. the elements In this group have . fi19uratlOn as an um I.e. s . c. I . h· · th· I 1 lour e ectrons In t elr outer 4 p 1) In elr outer-most e ec- : . 11 . orb·Itals, w hileth· she . Thus, each eletromc e mner I electromc .. 3d b· l b · fill d : ment In this group has a tenfi or It.a s ~re e\ng I t\' ~ dency to share these four elec-
rlom gOIng rom e emen 0; trons, to form covalent come ement. .. pound s, t here by gammg .. the · Pd· C enum, raeseo ymmm, ~ stable electronic configuration Neodymium, Promethium, Sa~ of its neighbouring Nobel Gas marium, Europium, Gadolinium, Terbium, Dysprosium, ; element in the periodic table. Holmium, Erbium, Thulium, : The elements in the group are ••1 chemically reactive. Ytterbium, Lutecium, These are the transition elements, and 1 Sub-Group IVA : Transition are also called the Lanthanides. ~ Metal Elements Actinium : Titanium, Zirconium, ~ Hafnium, Thorium , The following elements also have the same electronic con- ; Sub-Group IV sB : Main figuration as actinium (i.e. 5s2 : Group Elements ~ Carbon, Silicon, Germanium, 5p1) in their outer-most electronic orbitals, while the inner ~ Tin, Lead 4d orbitals are being filled, on ~ • group number going from element to element. ; the group number is the numNeptunium, Plutonium, Am- : ber assigned to the vertical colericium, Curium, Berkelium ~ umns of the structured list of
I1t117911nie Chemistry
===============;;;;;;;;;;;;;;
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106
all known elements in the periodic table. Elements within the same group have the same number of electrons in their outer electron shells. Thus, all elements in the same group have similar chemical properties. • group V elements the elements in this group have five electrons in their outer electronic shell. Thus, each element in this group has a tendency to gain three two electron, to form . I h . . a trIple c arged negauve lon, which has the stable electronic . f . confiIguratlon 0 Its nearest . hbo . N nelg urmg 0 bel Gas eIe. dicae. t bl · thepeno ment m The elements in the group are chemically reactive. Sub-Group VA : Transition Metal Elements Vanadium, Niobium, Tantalum, Protactinium Sub-Group VB: Main Growp Elements Nitrogen, Phosphorus, Arsenic, Antimony, Bismuth • group VI elements the elements in this group have six electrons in their
;roup I
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outer electronic shell. Thus, each element in this group has a tendency to gain two electron, to form a doubly charged negative ion, which has the stable electronic configuration of its nearest neighbouring Nobel Gas element in the p'eriodic table . The elements in the group are chemically reactive. Sub-Group VI A : Transition Metal Elements Chromium, Molybdenum, Tungsten, Uranium, S bG VI B M' G EUI - roup : am roup ements 0 Sui h S I . xygen, pur, e enmm, . . TellurIUm, Poloruum • group VII t:lements the elements in this group have seven electrons in their outer electronic shell. Thus, each element in this group has a tendency to lose an electron, to form a singly charged negative ion, which has the stable electronic configuration of its nearest neighbouring Nobel Gas element in the periodic table. The elements in the group are chemically reactive.
II ================..
lnorallnic Chemistry
Sub-Group VIla : Transition Metal Elements Manganese, Technetium, Rhemum Sub-Group VIIb : Main Group Elements Fluorine, Chlorine, Bromine, Iodine, Astatine
~ - gun metal ; a type of bronze usually having ~ 88-90% copper, 8-10% tin, : and 2-4% zinc. Formerly used ~ for cannons, it is still used for ; bearings and other parts that : require high resistance to wear . .I and corroslon. .
- group VIII elements this group contains three triads of elements, in the centre of the periodictable. Iron, Cobalt, Nickel, Ruthenium, Rhodium, Palladium, Osmium, Iridium, Platinum, These elements have the typical properties of metals, metallic luster, tensile strength, andrighdy.
: - gunpowder ~ a powdered mixture of sulphur, ; charcoal, and potassium nitrate, : used as an explosive.
- groups in the periodic table the elements are arranged in the sequence of their increasing atomic numbers into the periodic table, which is arranged in rows and columns, so that elements with similar chemical properties are in the same vertical column. The elements which are in the same columns are said to be in the same group, and they have similar chemical properties.
I
I
: - Gurney-Mott theory ~ a theory of the photographic ~ process that proposes a two; stage mechanism; in the fIrst : stage, a light quantum is ab~ sorbed at a point within the silI ver halide gelatin, releasing a : mobile electron and a positive ~ hole; these mobile defects dif~ fuse to trapping sites within the ; volume or on the surface of the : grain; in the second stage, ~ trapped electron is neutralised I by an interstitial silver ion, ~ which combines with the elec: tron to form a silver atom; the ~ silver atom is capable of trap; ping a second electron, after : which the process repeats itself, ~ causing the silver speck to grow.
[nora""ic Chemimy = = = = = = = = =
II
108
Gtaseits test I hill!cell
• Gutzeits test
II
,
the test is used to detect arsenic; H, in samples. The sample is I heated to release arsenic, which : t reduces silver nitrate to yellow ~ .., deposit Ag3 As. AgN03, which ; rapidly changes to silver. • gypsum
I
mineralCaS04,2H2o. Used in : the production of plaster of ~ paris, to control the rate of set- ; ting of Portland cement and as : a filler. It occurs in five variet- ~ ies: rock gypsum, which is of- ~ ten red stained and granular; ; gypsite, an impure earthy form : occurring as a surface deposit: ; alabaster, a pure fme-grained I translucent form; stain spar, ~ which is fibrous and silky; and : selenite, which occurs as trans- ~ parent crystals in muds and ; days. It is used in the building : industry and in the manufacture ; of cement, rubber, paper, and .I plaster of Paris. ; :
• Haber process
N2 + 3H2 ==> 2NH3 The process is reversible and exothermic. The process operates at high temperatures because at low temperature the rate of reaction would be too slow for equilibrium to be reached in a reasonable time. Thus, high temperature, 450 degC, and high pressure, 250 atmospheres, is used to increase the yield. An iron catalyst is used. The process was invented by the German chemist, Fritz Haber in 1909AD. However, Carl Bosch developed it for industrial use, leading to the alternative name HaberBosch Process .
I
: • half cell the Haber Process is the industrial method for the production ~ a half-cell is an electrode in conof ammonia by reacting nitro- I tact with a solution of ions, and ~ it forms one half of a cell. Gas gen with hydrogen. half cells have a gold or plati-
II = = = = = = = = = = [nora."ie Chemistry
109 num plate ill a solution with gas ~ electron short of the stable conbubbled o'.'er the metal plate. ; figuration of its neighbouring The hydrogen half-cell is used: Nobel Gases in the periodic I as a reference half cell and is : table. The halogen atoms can assigned the electrode potential ~ acquire a Nobel Gas structure of zero. Common half cells in- ; in either of two ways. clude the zinc and copper half : by accepting an electron from a cells. ~ donor atom to form an ionic • halides ; bond. Example of this : behaviour includes sodium chlohalides are compounds which ~ ride, potassium bromide and contain one of the halogen elements in chemical combination ~ sodium iodide, or with another element. The ha- ; by forming a covalent bond by : either lides of typical metals are ionic. ~. overlap of p orbitals of the atMetals form halides in which I oms. Example of this behaviour the chemical bonding is largely . covalent. The halide salts are the ; includes chlorine and bromine, : or fluorides, chlorides, bromides or iodides. ~ by overlap of a p ofthe halogen ; and the s orbital of another • halogens : atom. Example of this the halogens (from the Greek ~ behaviour includes hydrogen hals, salt) are the non-metallic I chloride and hydrogen broelements in group VII of the ~ mide. periodic table (i.e. fluorine, : Thus, the halogens exhibit an chlorine, bromine, iodine and ~ electrovalence and a covalence astatine). They are highly reac- ; of 1. Positive oxidation states of tive and are not found in the : III, V, VII are also known for elemental state in nature. The ~ all the halogens, with the excephalogens are used as oxidising I tion of fluorine. agents in many chemical reac- ; The melting points and boiling tions. The electronic configura- : points of the halogens increase tion of the halogens has one ~ with atomic number.
lnorgllnic Chemistry
======;;;;;;;;0;;;=========
II
no
hard wtZter I hmt e:cchfmaers
II
~~~~~~~~*
The electron affinity is at a ~ maximum in chlorine. The; halogens are oxidising agents, (i.e. they readily gain electrons ~ to form negatively charged ~ ; ions). Fluorine has the highest elec- : trode potential and is therefore ~ the strongest oxidising agent. I The high electrode potentials: illustrate high activity in solution. Fluorine with its high elec- I tronegativity, is the most reac- I tive non-metal in the Periodic I Table.
calcium and magnesium salts are the source of the hardness of water. Total hardness and calcium hardness can be distinguished chemically. The hardness may be classified as temporary hardness which is removed on boiling, or permanent hardness which is due to dissolved salts.
- heat capacity of constant pressure the quantity of heat required to raise the temperature of a gaseous system at constant volume - hard water by one degree Kelvin. water which does not form I h e I - eat energy . leather WI·th soap d ue, to th: presence of Ca Mg and Fe : all the substances possess heat compounds. Re~oval of these I ener~ More the temperature compounds renders the water I more IS the heat energy assosoft ciated with it. This type of en• I ergy is absorbed during en- hardness of water I dothermic reaction and given the hardness of water results our during exothermic reac. from dissolved salts of calcium~. non. and magnesium, which are In- I troduced into the water in the - heat exchangers environment when it passes I devices that enables the heat through limestone areas. The I from a hot fluid to be transnature of the materials dis- I ferred to a cool fluid without solved will depend on the ge- allowing them to come into conology of the region. However, I tact. The normal arrangement II ================= lnorgllnie
Chemistry
II
heatofctrmbusticn I heRtofneutralis;: HEATDDf_£.. ,NTH£
SMCOUIlION .........TOR
III
~ rued by an evolution of heat are ;
called exothermic reactions.
; • heat of formation :I the heat of formation of a sub: stance is the heat evolved when Heat of Formation for Ni,AI•.,
is for one of the fluids to flow I in a coiled tube through a jacket I containing the second fluid. : one gram-molecule of the subBoth the cooling and heating ~ stance is produced from its eleeffect may be of benefit in con- I ments. serving the energy used in a I chemical plant and in control; ling the process. : • heat of combustion ~ the heat ofcombustion of a sub- ; stance is the heat evolved when ~ one gram-molecule of the sub- : stance combines with oxygen. ~ When a substance burns in air, ; combustion is the process of : reacting a substance with oxy- ~ gen. In everyday life, we make I use of the combustion of coal : or gas in air as a source of heat. Chemical reactions accompa- I
InorgRni& Chemistry
•
heat of neutralisation
the heat of neutralisation is the quantity of heat liberated when one mole of a strong acid is neutralised by one mole of strong base. The heat Of neutralisation is independent ofthe nature ofthe acid or base. For this reason, it is assumed to be the heat released due to the recombination of the hydrogen ion from the acid and hydroxide ion from the base to form water. H+ + OH- ==> ~O
=====~===========
11
The heat of neutralisation is the ~ • heat of vaporisation _amount of heat evolved when i the quantity of heat required one gram equivalent of an acid : to vaporise a unit mass of a is neutralised by one gram ' ~ given liqu.id at constant temeq?ivalent of a base to give one I perature. ' gram equivalent of a neutral I h h d salt. Thus, in dilute solution, an : . eavy y rogen acid or base is considered to be I it is deuterium. completely ionised, and the I • heavy water (deuterium neutralisarion reaction is : oxide) Na( +) + OH( -) + H( +) + water in which hydrogen atQ(-) ==> Na(+) + 0(-) + I oms, lH, are replaced by the ~O , heavier isotope deuterium, The value of H should always , 2H. It is a colourless liquid, be - 5!.~6 kJ per mole f<:>r : which forms hexagonal crysneutralisatton ofany strong aad ~ tals on freezing. Its physical and strong base. i properties differ from those • heat of reaction of ,normal' water; r.d. 1.105; the heat of reaction is a differ- m.p. 38°C; b P 101.4°C. Deuence between the intrinsic en- ' terium oxide occurs to a small ergyintheproductsofachemi- , extent (about 0.003% by cal reaction and the intrinsic; weight) in natural water, from energy in the reactants, and it : which it can be separated by is either adsorbed or released ~ fractional distillation or by during the course of the chemi- ; electrolysis. It is particularly cal reaction. useful in the nuclear industry , because of its ability to reduce • heat of solution , the energies of fast neutrons the amount of energy change to thermal energies and bewhen one mole of a substance I cause its quenching cross-secis dissolved in a given solvent , tion is lower than that of hyto inftnite-dilution (in practice , drogen and consequently it to form a dilute solution). does not appreciably reduce
II
Heismberguncertainty principle I h~~r;"",lir:"",c"",om"",1JOU~"",nds~~~~~~1l""",3
the neutron flux. In the laboratory it is used, for labelling other molecules for studies of reaction mechanisms.
~
• heptane ; heptane, C7H 26, is the seventh : member of the alkane series of ~ hydrocarbons. It is a liquid ~ which is obtained from pctro• Heisenberg uncertainty ; leum. Its relative density is principle : 0.684, its melting point is -90.6 the Heisenberg Uncertainty ~ oC, and its boiling point is 98.4 Principle describes the uncer- I 0c. tainty with which the velocity and position of an electron in I . Hertz an orbital can be known. Only ; Hz, is the unit of frequency, and the wave function for the elec- : is the number of cycle per sectron is known with certainty, ~ ond. It is called after a German and the electron density at any ~ physicist, Heinrich Hertz. point is the square of the wave I • Hess's law of heat summafunction at that point. Thus, the I tion probability of ftnding an elec: Hess's Law ofHeat Summation tron at any point is propor~ states that the internal energy tional to the electron density at ; of a substance is independent of that point. : the process by which it was • Henry's law ~ made. Thus, if a chemical reacHenry's Law states that the ~ tion takes place in stages, the mass of gas which is dissolved ; algebraic sum of the amount of by a given volume of liquid at a : heat evolved in each separate fIxed temperature, is propor- ~ stage is equal to the total tional to the pressure of the gas. I amount of heat that would be In the case of water, the law ~ evolved if the reaction took only applies to those gases : place in one stage. which are slightly soluble in it, I : • heterocyclic compounds as the more soluble gases react with water to form ionic spe- ~ heterocyclic compounds are ~ ring compounds in which the cies in solution.
Inorglmic Chemistry
;;;;;;;;;;;================
II
ring contains carbon and other ~ similar chemical properties, elements, the commonest being ; a regular trend in physical properties, and oxygen, nitrogen and sulphur. a molecular weight difference of I 14 between adjacent members of the series, due to each member of the series containing an ~ extra -CH2- group (i.e. a me~ thylene group).
-----
---
- high density polyethylene high density polyethylene, HDPE, is an important plastic which is manufactured industrially by the polymerisation of ethylene. • Hofmann voltmeter a Hofmann Voltmeter is an apparatus for the volumetric analysis of gases produced during electrolysis. For example, the hydrogen and oxygen produced during electrolysis can be collected in separate graduated tubes, and volumes produced compared. _ homologous series a Homologous Series is a family oforganic compounds which have a common general formula, similar methods of preparation,
; - Hund's rule of maximum multiplicity I : the Hund's Rule of Maximum ~ Multiplicity states that when ; electrons occupy the orbitals : about a nucleus, and two or ~ more orbitals are at the same I energy level, each orbital is filled I singly, before any is filled douI bly. : - hybridisation ~ when bonds are formed beI tween atoms in the formation of molecules, there is a change in the nature of the Atomic I Orbitals in each atom. EffecI tively, new molecular orbitals are formed, and the electrons in these orbitals are those of the I molecule as a whole. The alteration of the structure of the atomic orbitals is called I hydridisation, as it involves
II =-============ lnorgll"U: chemistry
II
hybritlistlriorup I hybritlisation tp
• =========1l!!!:!!5
combining a number of orbit- ~ not be explained using the als to create an equal number; shape ofthe Atomic Orbitals on of new orbitals, where each of : the carbon atom. the new hybrid orbitals have ~ The Electronic Configuration of properties which are an average ~ carbon in the ground state (i.e. of those of the orbitals from ; the lowest energy state) is 1s(2) which they were created. : 2s(2) 2p(2). If energy is supA number of different types of ~ plied to raise one of the 2s elechybrid orbitals are known for ; trons to a higher energy level carbon in the organic com- : to fill the vacant 2p orbital, the pounds. ~ electronic configuration of car~ bon in the excited state, is Is(2) Hybridisation sp Hybridisationspl ; 2s(l) 2p(3). More specifically, Hybridisation Sp3 : the electronic configuration of The different hybrid orbitals, ~ the excited carbon atom is Is(2) which have different orienta- I 2s(l) 2px(l) 2py(l) 2pz(I). If tions in space, account for the ; we leave two of the 2p sub-orgeometry of the organic com- : bitals (e.g. the 2py(l) and pounds ofcarbon in which they ~ 2pz( 1) sub-orbitals) to fonn the appear;: :~ . ; second and third bonds of the • hybridisation sp ; carbon to carbon triple bond, : we can rearrange the other two the simplest alkyne, Ethyne (i.e. I sub-orbitals (i.e. 2s ( 1) and Acetylene), has a linear struc- ~ 2px(I»tofonntwoequivalent ture, where the two carbon at: hybrid orbitals. When these oms and the two hydrogens at- ~ new orbitals are arranged as far oms that are attached to these ; apart in space as possible, the carbon atom lie along a straight line. The carbon to carbon and ~ new orbitals are arranged in a : plane and are 180 degrees carbon to hydrogen bonds are ~ apart. • arranged as far apart in space ; The particular hybridisation of as possible. Thus, these bonds : the orbitals of carbon atoms in are at 1800 to each other. The ~ ethene, are called spl hybrids geometry of this structure canlnorgllnie Chemistry
================ II
=11=6=========* hybridisatitmspl I hybridisationspl orbitals, (i.e. they arises from the hybridising of one sigma orbital and one pi orbitals). The bonds between the hydrogen atoms and carbons, and the fIrst bond (of the double bond) between the carbon atoms of ethene are formed by the endon overlap of these sp 1 hybrids orbitals to form sigma bonds, and accounts for the 180 degree bond angles observed in this compound. The second and third bonds (of the triple bond) between the carbon atoms in ethyne is formed by the side-on overlap of the original atomic unhybridised orbitals (i.e. the 2py( 1) and 2pz( 1) orbitals) and these are pi bonds. • hybridisation Sp2
"
~
plained using the shape of the ; Atomic Orbitals on the carbon : atom. ~ The Electronic Configuration of ~ carbon in the ground state (i.e. ; the lowest energy state) is Is(2) : 2s(2) 2p(2). If energy is supI plied to raise one of the 2s elecI trons to a higher energy level to fill the vacant 2p orbital, the electronic confIguration of carI bon in the excited state, is 1s(2) I 2s(1) 2p(3). More specifIcally, : the electronic confIguration of ~ the excited carbon atom is Is(2) I 2s(1) 2px(1) 2py(1) 2pz(1). If ~ we leave one of the 2p sub-or: bitals (e.g. the 2pz(1) sub-or~ bital) to form the second bond ; ofthe carbon to carbon double : bond, we can rearrange the ~ other three sub-orbitals (i.e. the simplest alkene, Ethene, has ~ 2s( 1) 2px( 1) 2py( 1» to form a planar structure, where the . three equivalent hybrid orbitals. two carbon atoms and four hy- I When these new orbitals are drogens atoms that are attached I to these carbon atom lie in a arranged as far apart in space I as possible, the new orbitals are plane. The carbon to carbon : arranged in a plane and are 120 and carbon to hydrogen bonds I . degrees apart. are arranged a1t far apart in ; The particular hybridisation of space as possible. Thus, these : the orbitals of carbon atoms in bonds are at 120 degrees to ~ each other. The geometry of ; ethene, are called sp2 hybrids this structure cannot be ex- : orbitals, (i.e. they arises from
II ================_ Inorganic Chemistry
" hybrUliMtiontpl I indiulton
the hybridising of one sigma orbital and two pi orbitals). The bonds between the hydrogen atoms and carbons, and the ftrst bond (of the double bond) between the carbon atoms of ethene are formed by the endon overlap of these Sp2 hybrids orbitals to form s bonds (sigma bonds), and accounts c.lor the 120 bond angles observed in th IS compound . The second bond (of the double bond) between the carbon atoms in ethene is formed by the side-on overlap of the original ~tomic unhybridised orbital~ (l:e. the 2pz( 1) orbital) and ~ p~ bond prevents free rotation m the carbon to carbon axis.
.~~~~~~~~~
117
~ I
~
: ~
i
sp3 sp3
: ~
sp3
I " "tt" t pera..... -e : - 19ru on em ....u. .. . : Igrutton temper~ture 15 the tem.I perature to whlCh a£4 substance . ill i must. be .heated be ore It w : burn m aIr. ~ _ implosion ~ implosion is the inward collapse i of a vessel, usually when the ~ pressure of the gas in the co~ : tainer is less than atmosphenc ~ pressure. - hybridisation Sp3 ~ _ indicators the simplest alkane, Methane, i indicators are substances which CH4 , has a tetrahedral struc- : change colour at the end point ture, where the four hydrogens ~ of titration's. Indicators are that are attached to the central ~ compounds which change carbon atom are arranged sym- i colour in different concentrametrically about the carbon: tions of the speciftc analyte for atom, and arranged as far apart ~ which they are used, so as to in space as possible. The geom- ; give visual indication ofthe conetry of this structure cannot be : centration. explained using the shape ofthe ~ For example, a number of comAtomic Orbitals on the carbon ~ pounds have a different colour atom. I.
o
l1W111I1"" Chemistry
==============-=-11
in acid solutions than they have in basic solutions. These compounds are used in acid-base titration's as indicators, because they change colour during the course of the titration, to give a visual indication of the endpoint of the titration.
~
; ~
: ~
;
• initiation initiation is the ftrst step in a free radical mechanism that creates the initial free radicals necessary to start the sequence of reactions.
; • inner transition tpetals : the Inner Transition Metals are • industrial nitrogen fixation ~ the series of elements industrial nitrogen fIxation is ~ from Cerium (Atomic Number the conversion of atmospheric ; 58) to Lutetium (Atomic Numnitrogen into anunonia which is : ber 71), which are called the carried out using the Haber ~ Lanthanoids, and from ThoProcess. ; rium (Atomic Number 90) to • inert electrodes ~ Lawrencium (Atomic Number . 1 od 1 od : 103), which are called the mert e ectr es are e eCtr es I A· .ds .. I which do not undergo chemical: h~Ol. h d · th f i T e mner translt10n elements c ange ~g ~ course 0 an : are found between group 2 and electrolysIS expenment. I tb .. I t s · tb : e translt10n e!emen m e • influence of temperature I fifth row of the periodic table. on the rates of chemical ~ The transition elements are also reactions : known as the f-block elements. the influence of temperature on ~ These two series make up the the rates of chemical reactions ; f-block elements in the periodic depends on the Boltzman dis- : table, and their chemical proptribution of energies in the re- ~ erties of the elements derive actant molecules. Thus, the ~ from the filling of the fatomic higher the temperature, the ; sub-orbitals. The electronic congreater the fraction of mol- : fIguration ofthese elements are ecules that is present in an ex- ~ characterised as having full ; outer orbitals and full second cited (i.e. reactive) state. outermost orbitals, while the
II = = = = = = = = = = I'""1!_i& c~
second outermost orbitals are incompletely filled. Thus, in the case of the first inner transition metals series, the electronic configuration of the outermost and second outermost orbitals is 4s2 3d10, while the third outermost orbitals (i.e. the 4f level) are incompletely filled.
~
; : :I ~
; : I : I
~ : ~
;
• inorganic chemistry inorganic chemistry is the chemistry of all other sub. comstances other tanh orgaruc pounds, although it is convenient to include in it such common carbon compounds as are frequently encountered e.g. carbon dioxide, carbonates or are essential to placing the element carbon in its correct relationship in the periodic system of classification.
; • insoluble • inoraganic ion exchanges ~ a s.oli~ ~ s~id to be Ins?luble ~ these are hydrated aluminium ~ a liq~d It does not dISsolve m silicates N~~ S~ Os' xH2o. : theliqwd. It can be prepared by mixing ~ • instability constant soda ash (Na 2 C0 3 ), sand; thereverseofastabilityconstant; (Si02 )and alumina (~03)' It : the measure ofdissociation. is also known as permutit. The ~ . ul ' . AI2 S'12 S· xH20'IS ~ • inS ator . portlon Zeolte (Z) and inorganic ; a~ubstance~~a verylowelecexhanger is represented by : mcal conductlVlty. In lllSulators, . N~Z. ~ there is a wide separation be.. ; tween completely filled and • Inorgaruc : completely empty electronic pertaining to or composed of ~ energy levels. Most pure solid chemical compounds that do not ; ionic substances are insulators contain carbon as the principal : although impurities or imperelement i.e:, matter other than ~ fections may introduce semi~ conductivity. plant or arumal.
!f
°
Inora"nie Chemistry
===============;;;;;;;;;;;;;;;
II
120
- insulin ~ (C6H 1oO s)x' a fructose polysac-; charide of approximately 30:.1 fructofuranose units. It is : present in the underground tu- ~ bers and rhizomes of the ; Compositae. : ~
- .International Union Of ~ure And Applied ChemIStry
the Intemational Union ofPure and Applied Chemistry, IUPAC, is the organisation which regulates the nomenclature of chemical substances. In ~ particular, it prescribes the for;. mal rules for naming organic .: compounds. 1
: - interstitial compound ~ a crystalline compound in which ~ atoms of a nonmetal (e.g., car; bon hydrogen or boron) occupy -. interatomic distances . 'al POSlttons .. . the crys.. :. mtersnn m It IS the distance between the ~ tal lattice of a metal. (bonded or non- ;. NI VI = N V nuclei ofatoms . I l bonded) m a molecule or crys- . N V = unknown normally (tital. It can be determined by ~ tr~) ~d volume of the solution spectroscopy, electron diffrac- 1 to be titrated. ; NlV l = normality and volume · tion method etc. _ intercalation compounds ; of th~ titratin~ sol.ution. derivatives, particularly of : In aCld-?ase ntran~ns, close t? graphite, in which molecules are ~ the e~Ulvalence J?Omt, ther~ IS accommodated in holes or be- 1 a rapId change m pH which tween layers in the lattice. The ; m~y be. as~essed by ad~g a resulting compounds are easily : sUltable mdicator. The aad-base handled and stored (e.g.~ graph- ~ . indicator must change i~ co~our ite-SbF used as a fluorinating ; over a range of pH which IS as agent· gS;aphite-FeCI stable to : near as possible to that of , 3 I ' al . water. : eqUlv ence pomt.
II intrinsic me11JY I ionic bOnd
121
~ in sodium chloride, the sodium ; ion, N a+, is formed when a so2~O(g) : dium atom loses an electron to The gas is used as a mild aesthetic in medicine and dentistry, ~ form a positively charged sobeing marketed in small steel .I dium ion " Na+ cylinders. It is sometimes called ; the chloride i CaZ+ 2 : groups have been attached. An NaCI ~ ionic resin has negative ions I built into its structure and • intrinsic energy ~ therefore exchanges positive the intrinsic energy, U, (i.e. its : ions. A cationic resin has posiinternal energy) of a substance ~ tive ions built in and exchanges is the chemical energy of a sub- ; I1:egative ions. stance (i.e. the amount of energy stored within the sub- ; • ionic bond ~ an ionic bond, (which is also stance). : called an electrostatic bond), is ~ the attractive force between an Ion IS ; oppositely charged ions. an atom, or a group of atom, : An ionic bond results from the I which has gained one or more : transfer of one or more elecelectrons to form a negatively I trons from the outer shell of charged ion; or ; one atom to the outer shell of an atom or group of atoms : another atom. This type ofbond which has lost one or more elec- ~ is usually formed between eletrons to form a positively ; ments whose positions in the : periodic table lie just before or charged ion. ~ just after the Nobel Gases. For example,
NH4N03 (s) ==> N 20(g) +
1'""lJlIlIic Cbemistry
===============~ II
122 • ionisation potential the ionisation potential (i.e. the first ionisation potential) is the energy required to "remove the outermost electron from a neutral gaseous atom. The second, and third ionisation potentials, etc. relate to the removal of the second, and third electrons respectively, and are higher than the first ionisation potential, as each successive electron is removed against increasing positive charge. The ionisation potential is usually expressed in electron volts and is determined from spectra. • isomers isomers are substances which have the same molecular formula but which-have different structural formulae. Isomers are distinct chemical compounds, which have different physical and chemical proper" ties. Structural isomerism are very common in organic chemistry. • isotopes the isotopes of an element are the "atom of differeht atomic mass for that element. All at-
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: ~
oms of an element mUst have the same atomic number (i.e. the same number of protons in its nucleus) However, they may have different atomic mass (i.e. due to numbers of neutrons in the nucleus). The isotopes of an element have different physical properties. However, because they all have the same number of electrons, their chemical properties are identical. Isotopes are separated by the principal described in Graham's Law which uses diffusion as the method of separation. Hydrogen
'H
Helitml
A 'He
2 protons
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1 proton
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By using a simple mass spectrometer, EW.Aston discovered that all atoms of a particular element do not have the same mass. In the Mass Spectrometer, atoms are given a charge and accelerated in an electric field so that they move at high
II JoImDtllton IJohnDtllton speeds. When this beam of charged atoms passes through an electric field and a magnetic field, all particles of the same mass are focused on a line. The particles strike a photographic plate or detector so that their positions are recorded. These atoms of different mass number but having the same atomic number are called Isotopes. Hydrogen has three isotopes. The first isotope (called Hydrogen) has a mass number of 1 and has a single proton in the nucleus. The second isotope (called Deuterium) has a mass number of 2, and has one proton and one neutro~ in ~e nucleus. . The third ISOtOpe (called Tntium) has a mass number of3, and has one proton and two neutrons in its nucleus. Chlorine consists of two isotopes : The· first isoto~e has a mass nwnber of35 which has 18 neutrons and The second isotope has a mass nwnber of37 which has 20 neutrons in the nucleus.
123 ~ The observed atomic weight of ; chlorine is 35.46, which indi: cates that chlorine is a mixture ~ of these two isotopes, and that I the isotope with mass number ; 35 is the more abun~ant atom ; present. Indeed, th~ ISOtOpe ~f : mass numbe~ 35 IS approXlI mately three tlmes more abun; dant than the isotope of mass : number 37. ~. John Dalton ~ an English teacher and scientist, ; John Dalton (1766-1844) is the : originator of the modern ~ chemical Atomic Theory ofthe I Structure of Matter. ; He produced the fust list of : relative atomic masses in Ab~ sorption ofGasses 1805. I He discovered the Law of Par: tial Pressures of Gases ~ (Dalton's Law) in 1801AD, ~ which states that the pressure ; exerted by a mixture of gases : equals the sum of the partial ~ pressures of the components of I the mixture. ; His Law of Multiple Propor: tions states that if two ele~ ments, A and B, form more ; than one compound, the vari: ous weights ofB which combine I
[norglJnil;
Chemistry
================
II
124
JohnImnielll1tetones
II
with A are in small whole nwn- ~ established vector methods in ; physics. ber ratios. - John Daniell ; a British chemist, John Daniell ~ (1790-1845) discovered the : Daniell Cell in 1836AD. ~ _ Joseph Louis Gay-Lussac ~ . d h .. . a French ch emISt an p YSICISt, I Joseph Louis Gay.- Lussac ; (1778-1850), is known for the : Gay-Lussac's Law Law, which ~ he stated in 1808AD, which; states that when gases combine: in chemical reactions to give ~ gaseous products, the ratio of I tlie volumes of the reacting ; gases to that of the product is a : simple integral one. Avagadro's ~ Hypothesis is based on Gay- ; . Lussac's Law and on Dalton's : Law ofMultiple Proportions. I _ Josiah Gibbs J Willard Gibbs (1839 to 1903) ~ was an American mathemati- ; cian best-known for the Gibbs: effect seen when Fourier- ~ analysing a discontinuous func- ; tion. ~ He developed a mathematical : approach to thermodynamics. ~ Hisbook.~ctorAnaljsis.1881 ; :
- joule the joule is the unit of energy in the 51 system of units. It is the energy dissipated when a current of one. ampere flows through a resIstance of one hm o. . - ketones ketones are organic compounds of carbon, hydrogen and oxygen, where the ketone functional group, >C=O is contained within the molecule. The , Ketones
butaoooe9
CH3CHi"C-CH3 0II
'
propIIDOIIe
CH-C-CH 3 3
arethecompounw.whi~fonn a homologous senes which can be represented by the general formula R.Co.~, where Rand ~ are alkyl groups, and may be the same or different groups .. Ke~ones are formed by the OXldanon ofsecondary alcohols. ~CHOH[O] ==> R.Co.~ + H2
I
'1 1======
[MPH,,,,ie a..istry
II /ti.netie energy I lanthanides Secondary Alcohol aKetone The chemistry of the ketones is governed largely by the presence of the Carbonyl Group, >C=o. The polarity of this group means that the electrondeficient carbon atom of the carbonyl group is susceptible to attack by reagents which are rich in electrons. The first member of the homologous series of ketones is acetone, CH3 .Co.CH3 • Other aliphatic ketones are named by naming the groups attached to the carbonyl group and adding the word ketone. Using systematic nomenclature, the longest chain carrying the carbonyl group, > C= 0, is made the parent structure and compounds named by replacing the "e" of the parent alkane by the suffix "-one". The positions of substituents are indicated by numbers, where the carbonyl carbon atom is allocated the lowest possible number.
125
*================= ~ I
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;
• knocking knocking is the premature spontaneous explosion of the petrol mixture during the compression stroke in a petrol engine before the mixture is ignited by a spark. Knocking causes significant loss of power and may result in damage to the engine.
; • Kohlrausch's law ~ Kohlrausch's Law states that : the equivalent conductivity ofan I electrolyte at infinite dJlution is ; equal to the sum of the ionic : motilities of the ions produced I : by the electrolyte.
~ • lanthanides ~ the lanthanoids (also called lan; thanides, lanthanons or rare : earth elements) are the series ~ I
I
• kinetic energy I kinetic energy is the energy pos- : of elements from Cerium, sessed by a body due to its mo- ~ Atomic Number 58, to LuteI tium, atomic number 71 . tion.
Inorganic Chemirtry
================= II
IiItmt_tof~:1INIter l-ofcbellriallllJflil~
126
\
The lanthanoids all have two outer s-electrons (i.e. having a 6s(2) electronic confIguration). The lanthanoids and actinoids make up the f-block. The lanthanides are silvery very reactivemetals. • latent heat of evaporation of water the latent heat of evaporation of water is the amount of heat required to convert 1 gm. of water at 100 degreeC into steam at 1000C.
n~
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nent ions is brought together from infmity to form I mole of the ionic crystalline solid. This is also the energy required to remove tht' ions from their equilibrium positions in the crystal to infmity. A negative value for th~ heat change due to the lattice en~rgy indicat~s ~at the pr~ess IS exothermIc (I.e. heat IS being ~e!eased by the system). A POSItIve value for th~ heat change due to the lattIce en~rgy indicates ~t .the proce~s IS endothermIc (I.e. heat IS being absorbed by the sys-
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• latent heat of fusion of water the latent heat of fusion ofwater is the amount of heat required to convert 1 gm. of ice at 0 °C into water at the same temperature. . • lattice energy the lattice energy of an ionic solid is the energy released when the requisite number of moles of each of the compo-
II
rium
equilib.
~ the law ofchemical equilibrium ; (also called the law of mass ac-
~ tion) : states that the rate at which a .~ substance reacts is proportional ; to its active mass (i.e. to its ~ molar concentration) . : Thus, the velocity of a chemi~ cal reaction is proportional to ; the product of the concentra: tion of the reactants. I
_ law of conservation of ~ energy ; the law of conservation of en- ~ ergy states that in any chemical : transformation, energy is con- ~ served (i.e. it is neither created ; or destroyed). Although that : I energy cannot be destroyed or : created during the course of a I h . al .. be al : c ermc reactIon, It may - I tered from one form of energy: to another form. ~ . _ law of conservation of ~ matter or mass I the law of conservation of mat- ~ ter or mass states that in any : chemical transfonnation, matter ~ is conserved (i.e. it is neither cre- ; ated or destroyed). This means : that although substances change ~ into other substances in a chemi- ~ cal reaction, the actual number of; atoms remains the same. :I - law of constant composition the law ofconstant composition states that a pure compoWld has a fIXed and invariable composition (i.e. the compoWld always contains the same elements, united together in the same fIXed proportions by mass).
- law of definite composition states a pure compound has a fIXed and invariable composition. It was discovered by a French chemist, Joseph Louis Prout (1754-1826) . _ law of mass action .
the law of mass actIon states that the rate at which a chemiI cti d . dir tl ca rea .onalprocee s IS ec y proportIon to the product of the active masses of the reacting substances. The active mass is defmed as the concentration measured in terms of grammolecular weights per unit volume, usually 1 liter. This law was formulated by Guldberg and Waage in 1864 AD. _ law of multiple proportions the Iaw 0 f mul·tIpIe proportIons .
: states that if two elements com~ bine in more than one proporI tion to form more than one ~ compoWld, then the weights of : one of them which combine ~ with a fIXed weight of the other ; bear a simple, whole number : ratio to each other. This law was I : first proposed by John Dalton
=============== II
Int111Jllnic Chemistry ___
",,12~8~~~~~~~~~~
*
in 1803AD. For example, car- I bon forms two different oxides. I In carbon monoxide, 12 grams I of carbon is combined with 16 I grams of oxygen. However, in : carbon dioxide, 12g of carbon ~ combine with 32 grams of oxygen. Thus, the oxygen masses ~ combining with a fIxed mass of; carbon are in the ratio 16:32 or : 1 :2.
laWofOCtal1es I Lewis theory ofllCids 1/
tached to one, two or three carbon atoms, respectively. Le Chatelier principle states that a chemical system will respond so as to minimise the applied external forces. •
• lead compounds as pollutants there is anxiety that lead compounds are signifIcant pollutants in the environment. The use oflead compounds as additives to fuels is being phased out. • lepton the lepton is a fundamental subatomic particle.
I • law of octaves the law of octaves states that ~ each eight element had similar ; . al propertIes. . The I cheffilC awf 0 '. I octaves was an early attempt to : summarise the regularly repeat- ~ ing chemical properties of the ; elements with increasing atomic ; • Lewis theory of acids number. Lewis introduced the idea that • alcohols acids and bases had a reciproalcohols are the homologous ~ cal relationship and he introseries of organic compounds of ; duced the concept ofLewis congeneral formula, ROH, where: jugate acid-base pairs. R is any alkyl group or substi- ~ A Lewis acid is an electron pair mted alkyl group. An alcohol I acceptor. may be a primary alcohol, sec- A Lewis base is an electron pair ondary alcohol, or tertiary alco- donor. hoI, depending on whether the I Using this defInition, ammonia carbon atom attached to the is easily classifIed as a base. hydroxyl group, -OH, is com- NH3 + H30+ = = > NH4 + + bined with an alkyl group at- ~O
=
11 ________________________________
Inorganic Chemistry
II
129
lime Iliquefoction ofair
*================ Lewis Base + Lewis Acidiliwis Acid + Lewis Base In particular, water and the hydrated proton, H30 J, are a Lewis conjugate acid-base pair. Thus, the hydrated proton is able to donate a proton, (i.e. it is a Lewis Acid) and water is able to receive a proton by donating its lone pair of electrons (i.e. it is a Lewis base). H+ + H 20 ==> H 30+ It should be noted that the hydrogen ion exist in aqueous solution as hydrated proton. • lime lime, also called quicklime or calcium oxide, is a white solid compound formed by heating calcium in oxygen or by the thermal decomposition of calcium carbonate. • limestone limestone is a rock composed of calcium carbonate. • limiting reagents the limiting reagents in a chemical reaction is that reactant which are those that determines the maximum quantity of the product that may be formed. Inorganic Chemistry
~
; ~
: ~
; : ~ ~
• line spectra the line spectra of an element are the specific wavelengths of light which are emitted when the element is excited in an electric arc. The spectra are the discontinuous lines produced by excited atoms and ions as they fall back to a lower energy level.
~
• liquefaction of air ; in this process of the liquefac: tion of air, air from the atmo~ sphere is drawn through puriI fiers to remove carbon dioxide ~ and the resulting gas mixture is : compressed. The heat of com~ pression is removed by a cooler ; and the compressed air is : passed through a chilled con. :I denser to remove mOlsture. ~ The dry compressed air is then ; allowed to expand through a jet : and is cooled by adiabatic expan~ sion. This adiabatic process is ; repeated a number of times, : where the temperature drops at ~ each stage. Finally, the air be~ comes so cold that it liquefies ; on leaving the jet. The liquid air : obtained from the liquefier is ~ richer in oxygen than gaseous I air.
================= II
130
lilJuid I manufoaun ofsteel
II
• liquid ~ • main group elements a liquid is one of the states in ; the main group elements in the which matter can exist. A liq- : periodic table can be da,ssified uid has a fixed volume, but has as either being metals or nonno definite shape. I metals. The vertical columns in I the table are called groups. El• lone pair of electrons ements within the same group a lone pair of electrons are the I all have the same number of pair of electrons in a single sub- I electrons in their outer shell. ?rbital of:m atom, which do not ~ Group I Elements are known mvolved m a bond to another : as alkali metals. Group II Eleatom. ~ ments are known as the alka• magnetic quantum num; line earth metals and the group ber ~ of elements between group II : and III are known as the Tranthe magnetic quantum number, ~ sition Element. ml is used to indicate the direction of the sub-orbital in space. ~ • manufacture of ammonia The allowed values for the mag- ; the manufacture of ammonia netic quantum numbers de- : involves the fixation of atmopends on the subsidiary quan- I spheric nitrogen, there by maktum number of the sub-orbital. I ing it available for incorporation For each sub-orbital, I, the mag- I into a variety of other co~ netic quantum number, ml, I poun~s. The. Haber Pr~ess IS must lie in the range ml = + 1 : ~ed mdustrlally for this fixaor ml = - 1. W1·thin an orb·Ital, :loon. the sub-orbitals designated by I • manufacture of steel the subsidiary quantum num- ~ the manufacture of steel, which ber, 1 , have the same energy : is an alloy of iron and carbon level, but have different orien- ~ uses the basic-oxygen process, tations in space. ld process, by blowing oxygen onto molten scrap and pig iron at high pressure. This process
II ================= lnorgsnic Chemistry
II MRrlwwnikoffrule IMRrtin Heinric~K1R~:pro=th======="""1"""3,,,,,,1 removes impurities from the ~ metal in the form of slag and ; gases. The gases are burned off : at high temperature. Various ~ other materials are then added ~ to the iron in order to make dif- ; ferent types of steel. Steels con-: . . 1 f I 1 per cent . 0 tamlllg· over 1m '. ch rorruum are own as stam- I. less steel. .~ • Markownikoff rule the Markownikoff Rule specifies the orientation with which a small asymmetric molecule adds across the double bond of an alkene in an addition reaction. The MarkownikoffRule states that in the ionic addition of an acid to the carbon carbon double bond of an alkene, the hydrogen of the acid attaches itself to the carbon atom that already holds the greater number 6fhydrogens. For example, when hydrogen bromide adds across the double bond of propene, the hydrogen initially adds to that carbon atom which already has the greater number of hydrogen atoms directly attached to it (i.e. the terminal carbon atom) and
then the bromine then attaches to the other carbon of the double bond (i.e. the central carbon atom) to yield 2bromopropane. • Martin Heinrich Klaproth G h· M . a erman c emlst, artlll H elllrtC ' . h KI aprot h (1743 1817)·IS 1mown fcor his work on . al analYSIS. . In 1789AD·, cherruc
; he discovered Zirconium, Ura: nium and Titanium in 1795 ~ A.D. I
: I
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I
: The elements in this group have ~ a full outer electronic shell and ~ thus, the elements in this group ; have no tendency to lose, gain : or share electrons. Thus, the ~ elements in the group are I chemically inert. ~ All the elements in this group : are gaseous. Because of their I
132 chemical inertness, the elements in this group are called the Nobel Gases: Helium Neon Argon Krypton Xenon Radon
mIllS
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I melnng
II
mass/charge"values can be assigned, and from which molecular structure can be deduced. Francis William Aston (18771945) invented the Mass Spectrometer.
• mass mass is the intrinsic character- I • matter istic of matter and all matter has matter is defmed as anything mass. Mass is the amount of ~ that occupies space and that has matter in a substance, and it is I mass. measured in grams and kilo- These three forms are called the States of Matter: grams. I Solid, • mass spectrometer I Liquid, and the mass spectrometer is an inGas. strument for the separation and I Examples of matter are a book, analysis of ions and atoms. In I pen, ruler, the sun, the moon, the mass spectrometer a sample air, water, milk, etc., since each JIRDIP ___1111... epeetnaeter has mass and occupies space. I Radio waves, heat and light are I not matter since they have no mass. (usually gaseous) is ionised and the positive ions produced are accelerated into a high vacuum which is exposed to electric and magnetic fields. Ions ofdifferent types can be sorted via a detector into a mass spectrum. The mass spe_ctrum consists of peaks of varying intensity to which
I I
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• maximum-boiling mixtures a maximum-boiling mixture is an azeotrope having a boiling point higher than those of its components.
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• melting melting is the process by which a solid changes state from a solid to a liquid.
II ================= lnorgllnic Cbemistry
II melting point I metallic bond
133
~ ionised atoms of the metal and • melting point melting point is the tempera- ; the negatively charged electure at which a substance : tronic cloud is responsible for change state from being solid ~ the bonding in the metal. The ~ metallic bond is very strong and to being liquid. ; accounts for the mechanical • metal : strength of metals. a metal is an element which has ~ The metallic bond accounts for the physical properties of hav- ; the physical and chemical proplllg : erties of metals. The following . a lustrous appearance, being :I structure IS proposed for the malleable, being tenacity, hav- I metallic bond. ing high densities, and being ; Metals consist of positive ions good conductors of heat and : of the metal packed closely. The being good conductors of elec- ~ packing structure varies with tricity. Metals react with oxygen I the metal. to form basic oxides. Metals ~ vVhen forming this arrangereact with halogens to form : ment each atom of the metal halogen compounds which are ~ releases its valancy electrons, stable in presence of water. ; which are now free to roam Metals are electro-positive ele- : through the intervening spaces ments and form complex salts. ~ between the positive ions. This I space of moving electrons is • metallic bond the atoms in a metal are ar- ~ often referred to as the electron ranged in an orderly manner. : gas or electron atmosphere. Because metals have low ~ The positive ions are not free ionisation potential, they can ; to move, but they are able to easily lose their outermost elec- : vibrate. trons, which are then free to ~ The mutual sharing ofthis electravel in a cloud between all the ~ tron atmosphere by all the posiatoms of the metal. The elec- ; tive ions of the metal estabtrostatic attractive force be- : lishes a kind ofdiffuse bonding, I tween the positively charged
lnorgflnie Chemistry
================= II
134
*
matdlic chlorU/es I miscible "
which is non-directional, and is ~ • Michael Faraday ; an English chemist and physicalled the metallic bond. • metallic chlorides cist, Michael Faraday (1791those metals which are high on 1867), in 1821 began experithe electrochemical series form ~ menting with electromagnechlorides which are non-volatile I tism, and ten years later discovionic solids and have cubic ionic ~ ered the induction of electric lattices (e.g. sodium chloride). : currents and made the first dyThese ionic crystal lattices, ~ namo. He s~bsequen~y found which are composed of metal I that magnetIc field will rotate ions and chloride ions dissoci- : the plane of polarisation of , I li h ate in water but the ions them-: g t. Faraday also investigated selves are not hydrolysed (they ~ Electrolysis. ; • migration do not react with water). Many.metallic chlorides liberate ~ migration is the movement of chlonne with .. · toul h · when .d treated d . Ions th rough the soIutIon unc s . p .d aCI an manganese ~ wards the electrodes during dioXl e. I I · ·d libe e ectroIYSlS. rate: M any metallicchlon es hydrogen chloride gas when ~ • minimum boiling mixture warmed with concentrated I a minimum boiling mixture is sulphuric acid. : an azeotrope have a boiling I . I • methane : pomt ower than those of its I components. me thane, CH 4 , is the simplest : hydrocarbon and first member ~ For example, 95% alcohol, bo~ th· at a lower temperature than el. Th o fth e alkane senes. e me - I ane molecule has a tetrahedral : ther pure ethanol or water. shape, and there are single co- ~ • miscible valent bonds between the car- ~ when two liquids mix readily to bon atom to each hydrogen ; form a solution, they are said atom in the molecule. to be miscible.
II ================= Inorganic Chemistry
II mixture I molecul4rformula - mixture a mixture is composed of two or more constituent substances which are not bound together by a chemical bond. Mixtures can occur in each of the states of matter . 1 .. . f For examp e, arr IS a nuxture 0 gases, consisting of approximately 78% nitrogen, 20% oxygen, and smaller quantities of carbon dioxide, argon and water vapour. The composition of the atmosphere is changing gradually over time, due to the burning of ~ossil fuels and emissions. from
m~ustry.
Mixtures can be f~und .everywhere, as well as air. Mixtures can be found in practically all foods, the soil in the ground, oil and petrol and many other everyday substances. Alloys are a very important kind of mixture in modem life. Alloys are made by mixing two or more moltenmetalsunifonnlytogetheI; and allowing the metal in metal solution to solidifY on cooling.
135 ~ per unit volume and has units ; of mol per dm cubed or mol per ~ liter cubed. It has the symbol c. : _ molar mass
~ molar Mass is the amount of ~ substance per unit mass of sol-
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.
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. vent and has unIts of mol per kg I h tl bol . t as le sym m. - molar solution a molar solution, M, is one which contains one gram molecular weight (i.e. one mole) of the solute in a liter of solution. For example, 0.5M HCI means a hydrochloric acid solution containing 0.5 moles ofhydrochloric acid per liter of solution.
I
~ - mole : a mole is the amount of sub~ stance which contains as many ; molecules as are present in 12 : grams of Carbon 12. One mole ~ of a compound is its molecular ~ weight in grams.
~ - molecular formula I every compound has a molecu- molal concentration ~ lar formula, which shows the (molarity) : elements that are present in the molal concentration is the ~ compound and the number of amount of substance dissolved
Inorg~ni&
Chemistry
================= II
136
molecular weight I monomer "
===============*
atoms of each element in the ~ ; compound. : • molecular weight ~ molecular weight, M r , (also ; called relative molecular mass) : is the ratio of the average mass ~ per molecule ofnaturally occur- ~ ring form ofan element or com- ; pound to one twelfth (i.e. 1 / : 12) of the mass of a Carbon-12 ~ atom. The molecular weight is ; equal to the sum of the relative ~ atomic masses of all the atoms : I that comprise the molecule. : • molecule ~ a molecule is the smallest par- ; tide of a substance (i.e. of a : chemical compound) which can ~ . . an m . d epende nt existmatntam .I ence and consists two or more ; atoms bonded together. In gen- : eral, atoms do not exist indi- ~ vidually, but occur in groups I called molecules. For example, : a molecule of hydrogen consists ~ oftwo hydrogen atoms bonded ~ together. A molecule of oxygen ; consists of two oxy!?e~ atoms ; bonded together. Slmil~rlY, a : molecule of nitrogen consIsts of I two nitrogen atml1S bonded .to- ~ gether. A molecule that conslSts
of two atoms is known as a Diatomic Molecule. A molecule of helium consists of a single atom of helium, as it has a valency of zero. A molecule of sulphuric acid consists of two atoms of hydrogen, one atom of sulphur and four atoms of oxygen. Chemists give each type of molecule a chemical formula, showing what atoms are contained in the molecule and in what proportions. • monobasic acids monobasic Acids are acids that contain one ionisable hydrogen atom in each molecule. . • monohydrIC . alcohol . a monohydnc alco~ol contam one hydroxyl group ill the molecule. The !?ener~ formula ~f saturated aliphatic alc~hols IS C nH 2n + 10H, where n-1,2,3, etc. • monomer monomers are the low molecular weight materials from which high molecular weight polymers are formed in a polymerisation process.
II = = = = = = = = = = = = lnorgllnic Chemistry
II mortRr I neutmJ oxides
137
*================ • mortar mortar is a hydraulic cement, the best known of which is known as Portland Cement. • multiple bonds multiple bonds are formed between atoms in a molecule where more than one pair of electrons are shared between the atoms. Examples of molecules containing multiple bonds include, the alkenes, the alkynes, and the arenes. • naphtha naphtha is a hydrocarbon, which is used as a fuel.
I
I
I
pane, with lesser amounts of butane, and other higher alkanes. Natural gas is used as a fuel and for the manufacture of chemicals. nature of reactants the nature of reactants determine. the course of a chemical reaction. • negative ions negative ions are atoms or groups of atoms that have acquired one or more electrons.
I • I
: I : ~
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• natural abundance of an isotope the natural abundance ofan 1so.... topes is the ratio of the num- I ber of atoms of a particular iso- I • neutral oxides tope of an element to the total number of atoms of all the iso- ; neutral oxides are those oxtopes present. It is often ex- : ides, which show neither ba~ sic nor acidic properties when pressed as a percentage. ~ they react with water. Ex• natural gas ; amples include carbon monnatural gas is a naturally occur- : oxide and nitrous oxide which ring mixture of gaseous hydro- ~ are only slightly soluble in carbons. The approximate com- I water and nitric oxide which position of natural gas is 85% ~ is appreciably soluble in cold methane, 10% ethane, 3% pro- : water.
_...
lnorgllnic Cbemistry
================== /I
138
neranm I nobelgas "
• neutron the neutron is a sub-atomic particle, which resides in the nucleus, which is the central core of the atom, and it has tmit atomic mass and no charge. • nitrates nitrates are the salts of nitric acid, and are strong oxidising agents. • nitrogen cycle the nitrogen cycle involves the fixation ofatmospheric nitrogen and the transport of thg ammonia and nitrates so formed to the soil as nutrients for the growth of plants.
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• nitro-glycerine . . . . . I mtro-glycenne IS an 011 which : c~s.~s on coo~g. The liq- ~ wd IS ~y explOSIve, an~ deto- ~ nates VIOlently when subjected . to slight shock. I • nobel gas ~ the noble gas elements, whose ; atoms have full outer orbitals ~ tend to be stable, inert and not: chemically active, are found in ~ Group 0 Elements of the peri- ; odic table. The elements in this : group are Helium Neon Argon ~
Krypton Xenon Radon .Helium is an inert gas, because it has two electrons in its outer orbital. Only two electrons may reside in an s-orbital of helium and therefore the outer orbital is full. The noble gases are characterised by their stable electronic configurations. The small atomic radii and high ionisation potential values suggest the presence of strongly bound electrons. There are no molecules and the inert gases are all monatomic. Low values for the boiling points indicate the presence of weak Van der Waal's Forces. Melting points and boiling points increase with atomic size. They were called the inert gases, because it was thought that they would not react with other elements. Helium and Neon are not known to combine with other elements. However, compounds of the higher members of the noble gas group have been found, this is due to the presence of d orbitals (e.g. xenon tetrafluoride and krypton difluoride).
I
II = = = = = = = = = = lnorallnic chemistry
II rwmenc14tunofalcohols I rwmenc14;ofalcoho1S Helium is used along with o~gen by divers. Neon is used in neon sign electrical discharge tubes. Argon, krypton and xenon, are used in incandescent lamps. Radon a radioactive noble gas is used in the treatment of malignant growths. • nomenclature of alcohols alcohols are named by three different naming systems. The International Union of Pure
and Applied Chemistry system is analogous to the ones used for alkanes and alkenes. Systematic names for alcohols in the series are derived by applying the following rules : Select the longest continuous carbon chain carrying the hydroxyl group as the parent structure.
lnorgllnie Chemistry
139
~ Consider a particular alcohol to ; be derived from this structure : by replacement of one or more 1 ' : hydrogen atoms by different ~ atoms or groups of atoms. In; dicate the position of the hy: droxyl group in the parent ~ strucrure by the lowest possible ; number. Indicate the position of any substituents in the par: ent structure by a number. Re~ place the terminal "e" of the ; appropriate alkane by the suf: ftx "-01". Most of the simpler ~ alcohols are known by their I common names. These names ~ consist of the name of the alkyl : group, followed by the word ~ alcohol. For example : ; CH3C~OH (Ethyl Alcohol) : CH3CHCH30H (Isopropyl 1 : Alcohol) 1 It should be noted that similar ~ names do not always mean the : same classification. For ex~ample, isopropyl alcohol is a ; secondary alcohol, whereas : isobutyl alcohol is a primary al~ cohol. Compounds which are ~ too complicated for common ; names may be given derived : names. According to this sys~ tern, alcohols are considered to :1
================= II
140
nomenclR"; ofIIlIumes I nomenclRtu~ ofIIllulnes II
be derived from methyl alcohol, ~ The compound is therefore
CH30H by the replacement of one or more hydrogen atoms by other groups. The group attached to the carbon bearing the OH is named and then add the suffix carbinol to include the COH portion. • nomenclature of alkanes
; called a pentane, and since there : are two methyl substiments on ~ the linear chain, it is a ' dimethyl pentane. Give each carbon atom a nUn1ber so that the lowest possible ' numbers are used. In number'ing the carbon atoms always start at that end of the chain the nomenclamre rules foral- , : which will result in the lowest kanes requires that the names , numbers for the side chain of all alkanes end in "-ane". The I. groups. Thus, theave bo comd by. nomenclature system agree d· th fc . 1 . f . poun IS ere ore called 2 , 3 d 3·· 4 InternatlOna U mon 0 Pure , dim th 1 dA li d Ch . . now . e y pentane, an not , a~d 1pp e fc enust~ lSth ; -dimethylpentane. WI e y used or nammg ese: · f . I U se the prefiIX di,tn,. tetra, etc. and 0 ther c1asses 0 orgamc . di th b . ds d· ~ 1 be: to ill cate at a su snNent compoun ~ IS e y to I occurs more than once in the adopted ulllversally III due: ·d ch· f d ' SI e am 0 a compoun . Thi bl ·d . al course. s system ena es us . Wh th en. ere are two 1 ennc to d escn·be strucmres 0 fthe al· - I kan . all b b . subsnments at the same carbon . es sys~emarulnc y yo serv- ; atom, numbers are supplied for mg certam es. : h The longest continuous chain of ~ ~' saturated carbon is selected as ; ~CCC~CH the parent hydrocarbon and : CH 3 ds . f I 3 n~ehcdompounbo asb vanan~ 0 : 2-2-dimethylbutane. . y rocar n y replacmg 13th . -e y14th - -me ylhexane hydrogen atoms by alkyl,· D enva . n·ves 0 fthe alkanes such groups. H C ' as RBr and RN0 2, where R is CH3 CHCHCHCH3 3 : an alkyl group, are named as CH3 2, 3 -dimethyl pentane
this
II ================= 1'""1/""ie Chmfistry
II ""nometIC==UJ:!:!!:tu:!:!!:n=of,:!:!!:'al:!:!!:kmes=:!:!!:I:!:!!:nometIC==w:!:!!:.tu;""of,:!:!!:'al:!:!!:kynes========14=1 halo~nes and nitroalkanes, ~ structure when hydrogen atoms resperuvely I have been replaced by alkyl CH3CH2CH2CHCH3 ~ groups. The names of alkenes CI : all end in "-ene", (e.g. ethene, 2-chlo~opentane ~ propene, butene, pentene, etc. ). CH H ; CH CH 2 N0 2 (1nitro3butane )2 ~ • nomenclature of alkynes Alkanes with halogen and alkyl ~ the nomen~lature rules for substituents are named as ; alkynes reqUlres that the names haloalkylalkanes (not alkylhalo- : of all alkanes end in "-yne". The alkanes). ~ nomenclature system agreed by CH ; the International Union of Pure 3 CH H CHCHCH : and Applied Chemistry Br 3 2 3 ~ (IUPAC) for the naming of the I alkynes can be summarised as 3-brorno-2-methylpentane : follows: The longest chain in the above I example consists of five carbon atoms .
• nomenclature of alkenes but-I-ene, but-2-ene the nomenclature rules for alkenes requires that the names of all alkanes end in "-ene". The nomenclature system agreed by the International Union ofPure and Applied Chemistry, for the naming of the alkenes can be summarised as follows: Select the longest continuous chain containing the carbon to carbon double bond as the parent hydrocarbon and name the compound as a derivative of this Inorganic Chemistry
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1-hexyne a terminal alkyne
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3-hexyne an internal alkyne
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: Select the longest continuous ~ chain containing the carbon to ~ carbon double bond as the par; ent hydrocarbon and name the : compound as a derivative of this I structure when hydrogen atoms
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~ I mu:leophilie IIrrmuJtU SflbmtlltUm
142
have been replaced by alkyl groups. The names of alkenes all end in "-yne", (e.g. ethyne, propyne, butyne, pentyne, etc.). Give the position of the first carbon atom attached to aCe triple bond the lowest possible nmnber.
nucleon nucleons are the constituents of the nucleus in an atom, and include neutrons and protons.
I •
I
I
I I
• non-metal non-metal are the elements which has the physical properties of having a dull appearance, having low densities, and are poor conductors of heat and electricity. In general. non-metals react with oxygen to form acidic oxides.
II
• nucleophile nucleophiles are atoms, or radicals, which are attracted to electron deficient site& in a molecule.
I
• nucleophilic aromatic substitution nucleophilic aromatic substituI tion occurs when an atom or I group which is attached to an I aromatic ring is replaced by another atom or group. Ben• nuclear atom zene, C6H6, is the simplest amthe nuclear atom was proposed I matic compound and is often by Rutherford to explain the I presented as a six-member ring scattering of alpha particles by ~ with alternating single and gold foil, and the theory now : double bonds. However, these forms the basis of our under- I bonds exist as resonance hystanding of the chemical prop- brids, leading to significant erties of the elements. stabilisation of the ring sttuc.:.. ~~ I ture. Because of this stability of _ ..:::::- .....::::.... . I the aromatic ring, arenes tend T=~ to undergo substitution reac,.:- .-tions to preserve the aromatic
. '-J
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I:~~d I:;~ '.:::::- :-:
_---_ -
r ..4 ..... _ . _
,,- ......."'..
,-" .
;'r. _ _ " _
:~:~=~~:~~;~~'~;a:~
a hydrogen atom from the ring. Therefore, the double bonds in
...
11 _________============== 1""'l111"" Cbeminry
II
143
nucleus I oil pollution
an aromatic systems do not undergo the type of addition reactions observed for the Alkenes Alkynes. • nucleus the nucleus is the central core of an atom, in which the neutrons and protons reside. The nucleus contains most of the mass of an atom. • octane number the octane number of a fuel is an experimentally determined value for the fuel, which describes its combustion properties (i.e. knocking characteristics) relative to octane. • octet rule the octet rule states that the chemical properties of the elements repeat on a regular basis with increasing atomic mass, and that the chemical properties of each eight element is similar. Since the inert gases, with the exception of helium have eight electrons in their outer shells, this stable electronic configuration is called the octet rule. In chemical reactions atoms of elements tend to react
~ in such a way as to achieve the ; electronic configuration of the : inert gas nearest them in the ~ periodic table. There are a num~ ber of exceptions to the octet ; rule. The no ble gases are : known to be very inert chemi~ cally. In chemical reactions, the ; atoms of elements tend to re: act in such a way as to achieve ~ the electronic configuration of ~ the inert gas nearest them in the ; periodic table. Since all the in: ert gases, except helium, have ~ eight electrons in the outer I level, this concept is often re~ ferred to as the Octet Rule, to : which there are exceptions. This ~ rule is a guide to understand; ing bonding. In order to be: come stable, atoms with incom~ plete outer shells will attempt ~ to join chemically with another ; atom, and to share the electrons : of that atom in its own outer ~ shell, so as to fill it. This is ; called chemical bonding.
; • oil pollution ~ oil pollution is the degradation : ofthe quality of the water, when ~ crude oil, lubricants, fuel oil, ; etc. contaminate the aquatic : environment. I
l1W'1flJnic Chemistry
================= II
",,144""""",,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,fmi.er,,,,,,,,,,,,,,,,of.,,,,,Ji=lli; the atomic orbitals
_ order of filling the atomic orbitals the sequence in which the atomic orbitals in an atom are filled is as follows : Is 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f5d 6p 7s 5f6d 7p
I osmotic JIrmfIn
II
tion. The passage of water through the walls of living cells, which consist of very thin membranes that act as a barI rier to substances dissolved in the water, is an essential process in living cells and is an example of osmosis. In gen_ organic chemistry eral, the molecules of the solorganic chemistry is the study ~ ute are too large to pass of the chemistry ofcarbon com- I through such semi-permeable pounds. I membranes. Organic compounds form the chemical basis for life and are I more abundant than inorganic I compounds . Carbon compounds are made up of carbon atoms which form covalent I bonds with each of its I neighbouring carbon atoms in : - osmotic pressure either a chain or a ring and also I the osmotic pressure of a soform bonds with other atoms I lution is the pressure which mainly hydrogen, oxygen, ni- ~ must be applied to the solucion to stop osmosis. Osmotic trogen or sulphur. Compounds containing only ~ pressure is similar to gas prescarbon and hydrogen are known ; sure and is caused by the disas Hydrocarbons. solved substances (i.e. the solI utes) behaving as if they were _ osmosis I gases occupying the space volosmosis is the passage of a ume of the solvent. Under ossolvent through a semiperme- I mosis, a solvent always difable membrane which acts as I fuses from the less concena barrier to the passage of the I trated solution to the more solute dissolved in the solu- concentrated solution. I
I
II ================= lnorglJnu Chemistry
II
145
Oswald process ll»Cidising RlJent
• Oswald process the Oswald Process is the three stage process by which nitric acid is manufactured. Firstly, ammonia is oxidised, at high temperature (900°C.) over a platinum-rhodium catalyst, to form nitrogen monoxide. 4NH3 (g) + 502 (g) ==> 4 NO (g) + 6H20 The nitrogen monoxide cools and reacts with oxygen to produce nitrogen dioxide. 2 NO (g) + 02 = = > 2 N02 (g) Finally, the nitrogen dioxide reacts with water and oxygen to produce nitric acid. N02 (g) + 2 H 20 (1) + 02 ==> 4HN0 3 (1)
I
I
I
~ • oxidation number I
the oxidation number describes
~ the oxidation state of an atom
: or ion, and is the positive or ~ negative charge which each ; atom in a molecule would pos: sess if the bonds were purely ~ ionic. The oxidation number is ~ the same as the valency of an ; element. The oxidation number : of an element in its neutral ~ state, such as fluorine gas or I solid copper, is zero. The sum ~ of the oxidation states of all the : atoms in a compound will be ~ equal to zero. When balancing ; redox equations an increase in : oxidation number means oxida~ tion; decrease in oxidation I number means reduction.
• oxidation oxidation is the process in which there is a loss of electrons from an atom or ion. This definition applies only to reactions in which electron transfer occurs. Originally, oxidation was simply regarded ~ • oxidising agent as a chemical reaction with ; an oxidising agent is a substance oxygen. : which oxidises another sub~ stance.
Inorgllnic Chemistry
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146
ozone I periodic table
/I
========""""'* • ozone ozone, 03' is the triatomic isomer of oxygen, 02' and it is a powerful oxidising agent. The presence of ozone in the stratosphere is responsible for the absorption of ultra-violet wavelengths from the sunlight.
I
I
Pauli's exclusion principle the Pauli's exclusion principle specifies that no two electrons •
I
I
::![l[] 1p 2p 2p
I
I
which are in the orbitals about a nucleus of an atom may have identical Quantum Numbers. periodic law states that there are regularly repeating properties on going from element to element with increasing atomic number of the elements. These properties are best summarised in the modern version of the periodic table. The ftrst attempt at deftning a periodic law was the octet rule. • periodic table the periodic table is the structured arrangement of the elements in a chart that accenmates the relationships between the chemical properties of the different elements. The structure of the modern version of
I •
I
• paramagnetism paramagnetism in the transition elements is caused by the presence of unpaired electrons in the d sub-orbital, and results in these elements being attracted by a magnetic fteld.
I
I
I I
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147 .~~~~~~~=
the periodic ta?le is explained b~ the electroruc configuration o the elements. • pennanent hardness permanent hardness in water is caused by high levels of calcium salts (e.g. calcium carbonate) and. magnesium salts (e.g. magneSlUm carbonate) being dissolved in the water. • peroxide effect the peroxide effect results in the formation of a different product from that predicted by the Markownikoff Rule when an addition reaction takes place in th~ presence of a peroxide. PerOXIdes give rise to free radicals and a free radical mechanism fo; a chain reaction is believed to be responsible for the products observed.
~ cals), the Anti-Markownikoff ~ R~e specifies the orientation
. wIth which a small asymmetrlC . : molecule adds across the double ~ bond of an alkene, because un; der these conditions the reac: tants add across a double bond ~ in the opposite orientation to I that specifies in the ~ Markownikoff's Rule . I
; • peroxides : peroxides, R-O-O-Rare organic which contain ~ th.e ~eroXIde lmkage, -0-0-, ; WIthin the molecule. Peroxides ~ readily give rise to free radicals, : beca~e the. oxygen to oxygen I bond IS easily broken in these ~ organic molecules. : R-O-O-R = = > 2 R-O* ~ Peroxide Pe~oxide Free Radical I The ~os~ unportant organic : peroXIde IS benwyl peroxide, HBr - the peroxide ef1ect ~ (~6H5COO)2' which is the ini~ ~lat?r used in the polymer1933. Kh .... ch and May. ; lSanon of many industrially imabsence of : portant pol{mers (e.g. fillers, PErOxides (-0-0-) ~ etc) and adhesives (e.g. ; superglue, etc. ). p'eserlce of Oi 3 perO>Odes H3Ci-Oi,B< ~ ~eroxid~ are also the group of : morgarnc compounds that conIn the presence of a peroxides I tain the peroxide ion 0 2' 2· (which give rise to free radi- .
~
mol~cule~
~Ipipette
148
_ perspex
~
II
- physical change
perspex is a trade name for ~ a physical change is a change of plastics made from polymethy- ; state of a substance, where only lmethacrylate. the physical properties of the I substance are changes and the _ petrochemicals I chemical composition of the petrcchemicals are the industri- substance is tmaltered. ally important organic chemi- I : - physical properties cals which are derived from pe- I : the physical properties of a subtroleum or natural gas. ~ stance are those permanent ; properties which descri~ the - petrol petrol (i.e. Gasoline) is a com- : physical characteristics of the I . I plex mixture of hydrocarbons . matena. cOntaining 5 to 10 carbon atoms ~ - pi bonds in each molecule. ~ pi Bonds between atoms are _ pH ; formed by the side-on overlap the pH of an aqueous solution : of the atomic orbitals on the I .J:£r. is the reciprocal of the loga- : lUllerent atoms. rithm of the concentration of ~ - pig iron hydrogen ions in the solution ~ pig iron is the impure form of (i.e. the negative of the loga- ; iron produced in a blast furnace, rithm of the hydrogen ion con- ~ which is then c:st ~to pigs (i.e. centration). : blocks) forconvertmgatalater pH = -loglo[H+] ~ date into cast iron, steel, etc. A neutral solution has a pH of ; _ pipette 7.0'l\pHless.than7.0.indicates : a pipette is a graduated glass an aCld solunon, while a pH volumetric apparatus used to above 7.0 indi(:ates an alkaline I deliver a stated quantity ofliqsolution. The scale was intro- I uid in volumetric analysis by titration. duced by S.P. Sorensen.
II ================;;;;;;
[nora/If.it;
Chemistry
II
"""",,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,1,,,,,,,,,49
""R"",'lR"",1JC"",k"",'S"",Constll""""""",n"",t"",1"",PO"",la"",T"",mo"",lecule"""""""""" •
~ I SIOf1
tion of charge between the atoms.
I
-C-O I • Planck's constant Planck's constant, h, is the proportionality constant defining the relationship between the ener~ E, associated with a photon and the frequency, U, of that photon. E = hXu In 1900 AD, Plank made the assumption that the energy of light, and of radiation in general, may be absorbed and emitted in only in quanta (i.e. discrete packets of energy). h = 6.6X10-27 erg seconds
r '"
Polar Covalent Bond
Thus, a dipole (i.e. a separation ~ of charge along the length of I the bond) is formed and the ~ resulting bond is a polar cova: lent bond between the atoms. ~ In general, the polar bond is ; stronger than the covalent bond : from which it derives. Polar ~ compounds (i.e. compounds I containing polar bonds) tend to ~ have hydrogen bonding be: tween different molecules, and ~ to ha:e higher .boiling points . I and higher meltIng points than • polar covalent bond : would be the case in the absence when the atoms that are linked ~ ofsuch hydrogen bonding. by a covalent bond have significantly different electronegativi- ~ • polar molecule ties, the electron is likely to ~ a pola~ molecule is one that spend a greater time near I has a dIpole moment (i.e. one theatom of higher negativity, : in which there is some sepagiving to an unequal distribu- I ration of charge in the chemi-
lnot;!1l1nic Chemistry
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150
pollfIIiM I polyIwr
/I
cal bonds), so that one end of ~ CHO CH 2 0H (CHOH). the molecule has a positive I = = > (CHOH). CH 20H charge and the other a nega- : CI\OH . h I tlve c arge. : _ polymer I
- pollution : polymers are the long chain pollution is an undesirable ~ molecules obtained when a change in the physical, chemi- ; large number of small molcal, or biological characteristics : ecules combine together to I of the natural environment, : form a smaller number oflarge brought about by man's activi- ~ molecules. Polymers are long ties. There are two main classes ; chain molecules which have of pollutants : physical properties which are those that are biodegradable ~ significantly differ~nt from the and which can be rendered. monomers (i.e. the short chain harmless by natural processes : molecules) from which they are and need therefore cause no ~ made. Polymers are the basis permanent harm if adequately ~ for a wide range of materials ; which have become indispensdispersed or treated; and those that are non-bicxiegrad- : able in mcxiem society, includable, which eventually accumu- ~ ing synthetic fibers (rayon, nylate in the environment and I lon, terelene, etc), rubbers and may be concentrated in focxi ~ plastics (polystyrene, polythene, chains. Pollution can occur in : PVC, etc.), and the structural the air or in water. ~ polymers (carbon fiber, etc). _ polyhydric alcohol ; Polymerisation is the process by 1 h dri at h i s · : whith many small molecules po y}li c co 0 con~sev- ~ join together to form large eral hydroxyl groups m the; m 0 1ecules. The reactants "(.l.e. moIecule and are normally 0 b- : th all 1 ul) e all d c rode tained by the reduction of sug- I e sm mOde~ eschainar: . . : monomers an long pars. For example, sorbltal IS I cts fth 1 . ti obtained by the reduction of : U 0 ~ ~nsa o~ro~ cefss arfulec e p?alsymers. any glucose. . 0 use maten are natural
II polymerisatUm I polymers
151 .~~~~~~~
~lymers (e.g. wo?l,. cotton, ~ Polythene, (C2H 4 )n, (i.e. Polylinen, etc) or synthenc polymers I ethylene). (e.g. nylon, terelyene, rayon, : . . ~ • polymerlSatlOn etc). There are two general methods ; ~l~merisation is the process of for preparing polymers which : JOlfllng together a large numinvolves the linking of small ~ ber of small molecules to make molecules together to form ~ a smaller number of very large long chain molecules. The term ; molecules. The reactants (i.e. "addition polymerisation" is : the small molecules from which used where small molecules are ~ the polymer is constructed) are added directly to each other and ; called Monomers and products the term "condensation: of the polymerisation process polymerisation" is used where ~ are called Polymers. There are a molecule of water (or other ~ signific~t differences between ~mall molecule) is released dur- ; the. chemtcal and p,Q.ysical propmg the assembly process. : ertles of polymers and those of In general, addition ~ the monomers from which they polymerisations tend to proceed ~ are made. This polymerisation by a Free Radical Mechanism . process can occur by two differ. .l W h1 e condensation' :I ent mecharusms : by addition polymerisation tends to proceed ~ ~lymerisation and condensaby an ionic mechanism. ; non polymerisation The high pressure gas phase:I 2 ,-" ~~H • 2G.0 polymerisation of ethene to : - ~ . No· form Polythene involves a free .I _ l....-i;J rY0~H ~..-'i+c...tr!l: ~ l....radical mechanism. Thus, when ; /':f0 ° ethylene ~s htheated under great ~ . n '-~'H - C'~-+om-~-t. pressure m e presence of a . __ suitable catalyst a large number .; . po1ymers . o f molecules ofethene combine . together to form a much mall ~ po~ymers are glant molecules, number of molecutes ~~; built up from s.mali units called : Monomers which combined toNo
leiS
I
ImI1'/Jllnic Chemistry
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152
positive ion IpotmtiRl met;!JY
II
~ (c). that the collisions of par; ticles with each other and with vesthe walls of the containing I . : sel are perfectly elastIc. I (d). that the pressure of a gas is created by the particles striking the walls of the conI tainer. I (e). that the size of a particle ~ is negligible compared with : the volume of the container. ~ (t) . that the particles are elas; tic, no energy is gained or lost ~ ~~ collision. In an elas~c col~ hSlon. the on~y c~ange tn en. ergy IS the kinetIc energy of ~ ~e c<:>lliding particle will gain charged. ; kinetIc energy and the other . . : will lose an equal amount. • kin~tic. theory of gases. ~ The kinetic theory of gases is the kinetIc theory of Gases IS a ; largely the result of the work model that accounts for many : of Count Rumford James of the physical properties of ~ Joule and James Cla~k Maxgases. The main concepts ofthe ; well. ' theory are : : . (a). that a gas consists of small ~ • potenti~ energy . identical particles which exert I the potentIal energy IS the enno forces on each other except : ergy possessed by a body due ~ to its position. The potential at the instant of collision. (b) . that these particles move ~ energy varies when a body about at random and travel in ; moves from one position to straight lines between colli- another. SlOllS.
gether to form a repeating structure. Polymers are classified into : natural polymers which include proteins starch, cellulose and rubber. synthetic polymers, include bakelite, perspex, terylene (a polyester) and nyIon (a polyamide). The~e are man-made polymers, which are also called plastics. • positive ion positive ions (i.e. cations) are atoms or group of atoms that has either lost one or more electrons, making them positively
II ================= lnora."" Chemistry
II preparation ofacyl halides I purifica;!!!!!!of=Ort:S========1!!!!!!5!!!!!!3 Potential • .....-gy curve of tM ground stat. ot Nz
~ I
I
I
• proton a proton is an atomic particle. It resides in the nucleus, which is the central core of the atom. It has unit positive charge and unit atomic mass.
; • purification • preparation of acyl halides ~ purification is the physical or the -OH group in Carboxlyic : chemical process of removing acid is replaced by a halogen ~ contaminants from a comusing a halogenating agent such ; pound. The physical processes : may include sublimination, disas PCIs. ~ tillation, filtration, • propagation I crystallisation, or extraction. propagation is the step in a free ~ The chemical processes may radical reaction, where new : involve formation of a derivamonomer molecules are added ~ tive, purification of the derivato the growing polymer chain ; tive and recovery of the origiin the free radical process. : nal material in a pure form of • propane ~ the derivative. propane is the ~d member of ~ • purification of ores the alkane senes of hydrocar- I the purification of ores are imbons. I portant industrial processes and .. are the first steps to the extraction of the metals. Normally, I the ore is concentrated by sepaI rating it from the clay body in : which it occurs either by gravI ity, sedimentation, or by a I floatation process, before the extraction ofthe metal from the ore is started. This allows op-
Inorganic Chemistry
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154
erations with less inert materials during the extraction process. • quantum mechanics quantum mechanics is the mathematical description ofthe behaviour of particles and energy at the atomic scale.
~
; ~
:
~ ; I
I
• quantum numbers quantum numbers are used to describe the different aspect of the electronic shell, they are required to describe the properties of each atomic orbital. There are four quantum num-
I
:
Spin QJlantum Number, sThis quanrum number indicates the spin of an electron in the sub-orbital. Thus, for any atom, each electron in the orbitals about the nucleus in the atom has a unique set of quantum numbers, and no two electrons in the atom can have an identical set of quantum numbers.
~
; • quark : a Quark is a fundamental par~ ticle.
I. .
qwck1ime
.
;e:~c~pal QJtantum Number, n ~ q~c~e, CaO, (i.e. calcium
This quantum number de- ~ scribes the general overall en- ; ergy level and size of the orbital : (i.e. shell). ~ Azimuthal (or Subsidiary) ~ QJtantumNumber, 1 ; This quantum number de- : scribes the shape of the sub-or- ~ b·tal E h . . alII· d·· ~ded· . ac prbmchIPlls eVhi~ IS 1- ~ VI . mto su -s.e ,w ch are ; desIgnated by this number.: Magnetic QJlantum Number, m ~ This quantum number is used ; to indicate the direction of the : sub-orbital in space. I
oXld~) 1~ manufa~tured. by
burrung limestone ~l.e. calaum carbonate, Caco3) m a furnace. It reacts vigorously with water to produce slaked lime (i.e. calciumhydroxide). • Ra Radio. G 2 1 um roup e ement, symbol Ra, an alkaline earth metal, = 88 Ar = [226]. ' • racemate a mixture of equal amounts of two enantiomers. A solution of a racemate (or racemic mix-
z
II ================-- InorgIJn" Chemimy
, I
rtuiiantenergy I Ramanspearuscopy
155
I *~~~==~====== ture) will not rotate the plane ~ • radioactivity of polarisation of plane I radioactivity is the spontaneous polarised light because the ef- ~ disintegration of an unstable fects ofeach enantiomer exactly : nucleus, by the emission of a cancels out that of the other. ~ small particle (i.e. an alpha-par• radiant energy ; ticle or a beta-particle) or by the energy which is transmitted ~ change of the energy level ofthe away from its source. eg, energy : nucleus by the emission of a that is emitted when electrons ~ gamma-ray. transition down from one level ~ • radiochemistry to another. ; the branch of chemistry which ~ studies radioactivity and the ef.. • radiant power total amount ofenergy emitted : fects of the products of ~ redioactive decay on matter. by a light source per second.
• radiation ~ • radon energy in the form of photons. ; Group 18 element, symbol Rn, • radicals ~ Z = 86, Ar = (222). l.molecules or ions with one or ~ more unpaired electrons and: which consequently are gener- ~ ally very reactive. Also known I as free radicals. ~ 2. an old fashioned term for a : group one used to talk about a ~ "methyl radical" in the same ; way that one would use the ~ phrase "methyl group" : • radioactive ~ ; substance containing an ele: ment which decays. ~
lnor-glJni& Chemistry
• Raman spectroscopy a spectroscopic technique in which information is obtained about molecular energy levels by analysing the intensity of electromagnetic radiation scattered inelastically from a molecu1e as a function ofthe energy of the scattered radiation. The technique is named after the discoverer ofRaman scattering, Chandrasekhar Vankataswaran Raman, who in 1926 recorded Raman scattering from on pho-
================ II
156
tographic plates. The effect is so weak, however, that it was not until the advent of the laser that Raman spectroscopy became a viable proposition as a useful technique. Raman spectroscopy is complementary to the corresponding absorption process because different selection rules are involved. For an absorption of a photon to take place there must be a change in the dipole moment of the molecule in the course of the transition (a non zero transition electric dipole moment). In Raman spectroscopy, however, the requirement for scatering to occur is that there is a change in the molecular polarizability (a second rank tensor) in the course ofthe transition. For example, the infrared absorptions of carbon carbon double and triple bond stretching modes are weak due to the small electric dipole moment changes involved, but the corresponding polarizability changes are large resulting in strong bands in the vibrational Raman spectrum.
.. Raottlt'slaw I Rayleigh scattering 1/
Raoult's law Raoult's Law states that the vapour pressure of a solvent is reduced in the presence of dissolved solute. The law applies only to dilute solutions. The reduction of the vapour pressure of a solvent containing dissolved solute is proportional to the number of molecules ofsolute and is independent of their nature.
I • I
I
I
I
I
rate of migration the rate of migration is the speed at which the ions travel through a solution during electrolysis.
I • I I I
~ • rates of reactions
; rates of reactions are the veloci: ties with which chemical reac~ tions proceed. • ratio the relative size of two quantiI ties expressed as the quotient of one divided by the other; the I ratio of a to b is written as a b 'ora/b. I
I
I
• Rayleigh scattering when light is scattered by particles much smaller than the wavelength. The shorter the
" ==================
Inorgllnic Chemistry
II
reactants I reclaimedntbber
157
*================= wavelength, the more intense ~ - reactions of acyl chlorides the scattering. ~ acyl chlorides react readily with ; alcohols, _ reactants reactants are the starting ma- RCOCI + ~OH ===> terials in a chemical reaction, ~ RCOOR' + HCI water, and during the course of the ~ phenols and amines they are reaction, these are replaced by ; used in acylaction reaction. a new set of materials called ; - reactive plasma deposition products. ~ similar to CVD, except that an _ reaction mechanisms : rf plasma helps the decomposireaction mechanisms are the ~ tion/recombination process of detailed step-by-step descrip- ; the reactants. tions ofthe 'progress ofa chemi; - reactivity of a metal cal reactions. The exact sequence for the breaking and ; the reactivity of a metal is demaking of bonds, and the elec- : termined to a large extent by its tron transfers which give rise to ~ reduction potential. I • this process are described. : - receptor slte, or receptor ~ a membrane bound protein at
_ reaction rate
the time rate of change in the ; which there is some interaction concentration or amount of a I: with. a molecule or ion with bio: chemical consequences. reactant or product. I
- reaction with phosphorus pentachloride
reaction with phosphorus pentachloride is a characteristic of organic compounds containing a hydroxyl group and this reaction is used to identify these compounds in organic analysis.
Inorganic Chemistry
: - reclaimed rubber ~ rubber reclaimed from used or I
~
: ~
;
waste rubber goods. The method consists of heating the material with a dilute solution of sodium hydroxide for 12-20 hours at around 180°C.
=================_11
158
recrystallisation I reduction
II
• recrystallisation I or atoms of oxygen or hydromethod of removing soluble I gen, then another substance impurities from a crystalline must gain them. Redox reacsample or for improving qual- tions always involve the swapity of crystals. Consists of dis- I ping of electrons. solving the sample in the mini- I • redox titration mum amount of hot solvent. ; redox titration's are volumetAs the system is allowed to ric determinations titration's cool gradually, the solubility ~ in which electrons are transdecreases and the sample crys- ; ferred from a Reducing Agent tallizes out leaving soluble im- I to an Oxidising Agent. The purities in solution. The same principle holds as in slower the cooling process the I acid-base and Argentometric greater the quality of the crys- I Titration's. tals. I • reduced mass • rectifier I =mlm2(ml+m2) a device that turns ac power into I • reducing agent dcpower. a substance that can donate • red litmus electrons to another substance a water soluble dye extracted I or decrease the oxidation from lichens. It is red under acid I numbers in another substance. conditions and blue under alkaline conditions. Often used im- I • reduction pregnated on paper (lit:P1us pa- I reduction is the process m per) as a rough indicator of : which an atom or ion gains I electrons. This definition apacidity or alkalinity. • redox reaction I plies only to reactions in which electron transfer occurs. redox reaction occur when I Originally, reduction was simOxidation and Reduction takes ; ply regarded as a chemical replace in the one reaction. If : action with the loss of oxygen. one substance loses electrons, ~
II ================-- lnorgani& Chemistry
II reduetionbycarbon I retativityprinci;e
159
• reduction by carbon ~ isotopes of an element. For reduction by carbon is an im- ; example, the relative atomic portant method for the extrac- ~ mass of carbon is 12.0 II due tion of metals from their ores. : to a small amount of naturally ~ occurring carbon. • reduction reaction a reaction in which a substance ~ • relative density gains at least one electron. I the relative density, r , of a d • reforming ~ subs~ance is the ratio of the c. . . th . f : denSIty of the substance to the c. b relormmg IS e conversIon 0 I d . f . h h' lk . . ensity 0 some relerence su straig t c am a anes mto . - F l"d l'd b h d h' lk b I stance. or lqW s or so 1 s, ra~ e c:m aal a~es Y: the reference substance is wacrac ng or y cat ync reac- ~ ter. This quantity was for~ medy called Specific Gravity. tion . • refractory metals ~ • relative molecular mass include tungsten, tantalum I relative molecular mass (i.e. and molybdenum; used for electrode materials because ~ molecular weight) is the ratio : of the average mass per molthey have a low, uniform sur~ ecule of the naturally occurface potential, do not oxidize, ; ring form of an element or and are bakeable. ~ compound to the 1/12 part • relative atomic mass, Ar : of the mass of the carbon-I2 the mass of an atom relative to ~ atom. It is equal to the sum the carbon 12 nucleus which has ; of the relative atomic masses a value of 12 exactly. The rela- : of all the atoms that comprise tive mass is a pure number. ~ a molecule. Relative atomic mass used to ~ • relativity principle be known as "atomic weight", and unless specified normally ~ the basic laws of physics are the refers to a weighted mean ; same in all inertial reference over the naturally occurring ~ frames.
InD'1Jtmic Chemistry
================= II
160
relaxati;imes I resonance Raman spectroscopy
II
• relaxation times I a formula which is intermediconsist ofTl (longitudinal re- I ate between all possible formulaxation time) and T2 (trans- lae. For example in the strucverse rel
II ================== Inorganic Chemistry
1\ resonant two-photon ionisation
I reve;osma=~ns~'========~~16=1
tional Raman spectra. However, at the heart of many important biomolecules such as haemoglobin and cytochrome there is a complexed transition metal ion i.e. chromophore. Resonance Raman spectroscopy, therefore, can study the active sites of these important molecules. The development of tuneable dye or solid state lasers over a wide range of frequencies has obviously increased the scope of this technique. • resonant two-photon ionisation a process in which two photons strike a sample and ionise the molecules. One good thing about this process is that the product ions generally have known structure. • rest mass the mass of an object as measured in a reference frame where it is at rest. • reststrahlen filter utilises the phenomena that reflections of white light from crystal surfaces will contain only one region of the spectrum. Inorganic Chemistry
~
• resultant ; the sum oftwo or more vectors. • • retroretlector . ; see corner-cube prism ; • retrosynthesis (or retrosynthetic analysis) ~ when practicing organic syn• the tic chemistry it is only ~ natural to study a target mol: ecule with a view to disassem~ bling (or "disconnecting") it ; to see how it may be con: structed from simpler mol~ ecules. However, this process ~ was given a firm procedural ; foundation by E.J. o:>rey (who : received the Nobel Prize for ~ his efforts) and is now known ; as retrosynthesis. • • reverse osmosis ; reverse osmosis is a process of : obtaining pure water from sa~ line water, as in a descalination ; unit. Pure water and the salt are : separated by a semi-permeable ~ membrane, by raising the pres• sure of the salt water above the ; osmotic pressure. Then, the : solvent, water, is able to pass ~ through the membrane, leaving • the solute (i.e. the dissolved ~ salts) behind.
================= II
1-eversible process I ring
162
• reversible process for a system at equilibrium, a reversible process takes place when at any stage in the process an infinitesimal change in the reaction conditions (pressure,temperature, concen. ) can reverse the d·Irectratlon tion of the chemical change. • reversio right-to-Ieft reversion of an Image. • Reynold's number characterises the onset of turbulence in a tube. Re = 2vr( rho )/n, where n = viscosity, r=radius of tube, rho = density of the fluid, v=velocity of the fluid; If Rc <2000, there is laminar flow; if R e>2000, there is turbulent flow. • R.value an R f value of a substance is the ratio of the distance that the substance moves in a chromatographic separation, to the distance that the solvent moves. • rhenium Group 7 transition metal of the third series, symbol Re, Z = 75, Ar = 186.207.
II
rhme rotating hanging meniscus electrode. • rhodium
I •
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I
I I I
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Group 9 transition metal ofthe second series, symbol Rh, Z = 45, Ar = 102.905. • rhomboid prism used for lateral deviation of a light ray. • ribonucleotide reductase the enzyme in all -organisms that catalyses the conversion of nucleosides to deoxynucleosides.
• rideal eley mechanism for heterogeI neous catalysis reaction occurs due to a collision between a reactant in the gas phase and lone chemisorbed on a surface. I
I I
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• ring a ring is an arrangement of atoms in a molecule to form a closed chain. Ring compounds may consist of an alicyclic ring structure (e.g. cyclohexane), an aromatic ring structure (e.g. benzene), or a fused ring structure (e.g. naphthalene).
II ================ Inorganic Chemistry
" ring closure I ruby
- ring closure ring closures are chemical reactions in which one part of a molecule reacts with another part of the same molecule to form a ring structure. Examples of ring closures include the formation oflactams and lactones.
163
*================ ~ - roots blower
a type of vacuum pump ca; pable of pressures down to .01 : torr. I
I
: - rosaniline ~ triamino diphenyl tolyl hyI droxy methane, component of ~ fuchsine dyes, made by oxidiz: ing an equimolar mixture of ~ aniline, 0 toluidine and p tolui; dine. : _ rotating disk electrod I e : method to determine kinetics of
- RNA ribonucleic acid; a chemical found in cells that serves as an intermediate in the synthesis of . thth . protems; e ree major types are called messenger RNA I If you have the ( m RNA) , n'b osoma I RNA:I electrodes. I d b ' di k, th (rRNA) and transfer RNA : e ectro e e a rotatmg s e I current of the sample ca~ be (tRNA).' : related to the speed of rotation. I - Rochelle's salt : - Rowland ghosts Rochelle's Salt, (i.e. Sodium Po- I . . . . : SpUrIOUS mtenslty maXImum tassium Tartate), ~ spurred from periodic errors in KNaC 4 H 4 0 6 .4H 2 0, is a ; the spacing ofthe ruled grooves colourless crystalline salt. : in a diffraction grating. I - rolling friction : -rpm the friction from when one ~ radical pair mechanism body rolls across a surface; I b'di urn generally much smaller than :-rul the sliding friction. ~ group 1 element, an alkali ; metal, symbol Rb, Z = 37, Ar - root-me an-square speed : = 85.4678. (rms) I
the square root of the average :I - ruby of the squared speeds of gas : aluminum oxide, Al20 3 . I molecules in a sample. Inorganic Chemistry
================= II
164
rost I SAM
=================* • rust rust is a hydrated ferric oxide which has the approximate chemical composition shown.
I
I
• ruthenium group 8 transition metal of the second series, symbol Ru, Z = 44,Ar = 10l.07.
I I
• s block elements elements in which s orbitals are being filled. • s orbital an atomic orbital with a quantum number 1= 1.
I
I
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of saturated sodium chloride in a glass tube, used to connect two half cells. • saltpetre name given to natural deposits of potassium nitrate. Also known as nitre. An important compound in the manufacture of explosives. Chile was the major source of saltpetre and the naval blockade of Germany in WWl ought to have meant that they would run out of explosives in 1916. However, after the invention of the tIaber process in about 1908 and its development into a viable industrial process by Bosch duringthewar.
• sacrifical anodes I are metals that are used to I protect valuable metals i.e., iron from corrosion by sup- I plying an excessive amount of ~ • salts electrons and thus not allow ionic or electrovalent comany chemical reaction involv- I pounds in which one or more ing oxidation to take place on I acidic protons of an acid have its surface. been replaced by cations, usu• salt ally metal or ammonium cata salt is the product of the I ions. The word "salt" in daily neutralisation of an acid by a I use is taken to mean sodium base. Salts are usually ionic sol- I chloride, NaCl, which is the sodium salt of hydrochloric acid. ids. • salt bridge a salt bridge is the linking struc-
r'
• SAM I
self-assembled monolayer.
consisting of a viscous gel ' Inorga1Jic Chemistry
II
165
samarium I SeE
- samarium ~ _ saturated solution a lanthanide or rare earth ele- I a saturated solution is a solument, symbol Sm, Z = 62, Ar ; tion contains as much solute as = 150.36. : the solvent can hold (i.e. dis_ saponification ~ solve) at a that particular temreaction (hydrolysis) of an es- ~ perature. ter with an alkali to give an al- ~ _ Sb cohol and the salt of a carboxy- ~ antimony Group 15 element, lic acid. When the ester is that, b I Sb (f L' f f 'd th d ' I sym 0 rom atm o a atty aCI e pro uct IS a ''''b ") Z = 51 Ar = C'. 'd I h' h . ' Stl num latty aCI sa t w lC IS a soap I ' , molecule (long hydrophobic: 121.75. chain with a hydrophilic head). ~ _ Sc " " , ~ Scandium Group 3 element, H e,:ce the name C lrom' .sapo Latm for soap. ; symbol Sc , Z = 21 , Ar = ~ 44.9559. Technically, Scandium - sapphire : is a member of the first row Al20 3, aluminum oxide. ~ transition metal series, but its -SATP I chemistry is principally that of standard ambient temperature ~ the &3+ ion which has no d elecand pressure; corresponds to : trons. 25 C, 1 bar. I
- saturated compound a saturated compound is one in which all the atoms are linked by single bonds. Saturated compounds react with other compounds by undergoing substitution reactions. If a saturated compound undergoes an elimination reaction, an unsaturated compound is formed,
: - scalar : a quantity which has magnitude ~ but no direction associated with ; it. Familiar examples of scalars ; are temperature, volume and : pressure. I
I
:-SCE I
: standard calomel electrode.
"",16"",6========== ;hiff'Sreagent I SchrodingereqURtWn
II
• Schiff's reagent ~ • Schrodinger equation (not to be confused with a shift I the equation at the heart of reagent) a solution of fuchsine ~ Schrodinger's formulation of (the hydrochloride of rosa-quantum mechanics. niline) decolourised with sul- I The most general form of the phurous acid. A test for ali- I equation is time dependent, but phatic aldehydes and aldose for problems of atomic and sugars which immediately re- molecular structure the time store the red violet colour. Aro- I dependent equation reduces to matic aldehydes and aliphatic I the time independent ketones restore the colour: SchrOdingerequationwhichhas slowly, while aromatic ketones ~ the form are unaffected. I H '" = E '" where H is the Hamiltonian, • Schiff's test the operator corresponding to a test for cholesterol. When ; the total energy of the system, FeCl 3 and concentrated: psi is the wavefunction of the sulphuric acid are heated with ~ system and E is the energy of chol~sterol a violet .residue is ~ the system. an obtamedonevaporanontodry- I This equation is ness. I eigenfunction/eigenvalue pro~ : lem. Once one has the Hamil• Schott irg 11 calcium aluminate; transmits I tonian of a system, the mathematical problem is to find light between .3-5.5 microns. fimctions which, when operated • Schott irg 2 ~ on by the Hamiltonian, yield germanate; transmits light ; the same function multiplied by between .3-4.6 microns. : a number (which equals the • Schott irg n6 energy of the system). calcium alurninosilicate; trans- I Boundary conditions generally ·ts light between .3-. 4 75 ml-. I result in quantisation a range ffil (often of infinite size) of "stacrons. tionary states" is found. Each
1\
================= lnorgIJnic Chemistry
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167
scientific method I Seeback effict
state has a discrete energy and ~ • secondary cell is described by one or more ; a secondary cell is an electro~ chemical cell for the production quantum numbers. • .entific method : of electricity. After use the secsc~ d al . hi h I ondary cell can be recharged by . I. e lun ament way m w c : . d . hi h I passmg an e ectnc current SClence progresses an m w c . thr h th 11· th . d d d· oug e ce m e opposlte dge ?ur ~owle an un. ers~. - ~ direction to that delivered durElf d mg mcrease. Essentially It IS . . . d b I mg usc. xamp es 0 a secon d base on expenment an 0 ser- : 11· I d th I d ·d vation. I ary ce mc u e e ea -aCI : battery used in cars, and the • seRF ~ nickel-cadmium cells used in self-consistent reaction field ; portable electrical devices. method. A method for calcu- ; • secondary standard lating the energies of molecules ~ a secondary standard is a workin a reaction. : ing standard material which is • second law of thermody- ~ used in the laboratory as a namics ; working standard, and which the entropy of an isolated sys- : has been calibrated against a tem increases in the course of a ~ primary standard material of spontaneous change. ~ known composition.
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• secondary alcohol a secondary alcohol is one in which the hydroxyl group [OH] is attached to a secondary carbon atom (i.e. a carbon atom which has one hydrogen atoms attached to it).
~
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• secondary treatment secondary treatment involves the biochemical oxidation of a sewage or trade effiuent to meet the standards before its discharge to the aquatic environment.
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• secondary amine : • Seeback effect compound in which two hydro- ~ when a metal has a temperagens of ammonia have been re- ~ ture gradient, it has a voltplaced by organic groups. Inorganic Chemistry
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168
.. selenium I shape ofionic compound
II
age. The difference in ther- ~ tion is normally achieved by mally induced voltages of two ; chromatographic methods. metals will cause a net voltage ~ • serine in a junction. abbreviated to ser, 2 amino 3 - selenium hydroxypropanoic acid, pKa valGroup 16 element, symbol Se, ' ues = 2.21,9.15, an amino acid , occurring in proteins. [Chime Z = 34,Ar = 78.96. _ semiconductor structure up shortly. ] semiconductors are materials whose electrical conductivity is intermediate between that of conductors and that of insulators. The electronics industry is based on the beneficial uses of the electrical properties ofsemiconductors. - sensitisation development of an allergic reaction when exposed to a chemical, especially involving the skin or lungs.
~
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- SERR spectroscopy surface-enhanced resonance Raman spectroscopy; a Raman method used because it has excellent selectivity to the microscopic environment and orientation of things adsorbed on surfaces.
, - SERS : ~ , : ,
surface-enhanced Raman scattering • shape of ionic compound
ionic compounds exist in a crys- separation talline form in the solid state. separation is required to isolate For example, the electrostatic pure compounds from mixtures ' attractive force which exist beand is a prerequisite to the, tween the positively charged analysis of mixtures. In chemi- sodium ion and the negatively cal manufacturing plants, sepa- charged chloride ion cause ration is normally achieved by ~ these oppositely charged ions to distillation, sublimination, ; arrange themselves as close as crystallisation, or by ftltration. possible in a crystal lattice. The In analytical chemistry, separa- exact structure of the unit cell
II ================= InD11IlIni& Chemirtry
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SHE I silicon
169 .======~========
of the crystal structure will de- ~ Each s orbital in a shell forms pend on the size and charge on ; the s subshell; each' three degen: erate p orbitals in each shell each of the ions. I : forms the p subshell and so on . • SHE lOne can label the subshell with standard hydrogen electrode; ; the principal quantum number defmed as having ov. : the s orbital in the n = 2 shell is • shear modulus ~ the 2s subshell . the modulus of rigidity; con- ~ • shg cerned with the elastic deforma~ second harmonic generation. tion of a body in which an applied force results in the shape I • shielded ofabody. ; when the sigma value in NMR . IS greater than zero . • shells and subshells ~ Deshielding is when the value each set of orbitals with the I is less than zero. same value of n, the principal quantum number, forms what I . SI unit is known as an energy shell. ; stands for Systeme InternaAs a legacy from some early : tional d'Unites, a international work on atomic spectroscopy, ~ system which established a the n = 1,2,3 .. shells are also I uniform set of measurement known as the K, L, M .. shells, ; units. respectively. ~ • sigma bond Each subset of each shell with : sigma Bonds (s Bonds) are the the same value of 1, the azi~ single covalent bonds formed muthal quantum number, is I between two atoms by the endknown as a subshell. ~ on overlap of the atomic orbitThere are (21 + 1) orbitals in : als on the different atoms. a subs hell with azimuthal I quantum number 1, and a to- : • silicon tal of n 2 orbitals in total in a ~ Group 14 element, symbol Si, shell with principal quantum I Z = 14, Ar = 28.0855. numbern. Inorganic Chemistry
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170
silicon carbide (or carborundum) I slaked lime
II
===============*==============
• silicon carbide (or ~ carborundum) ; ·C, M e 40 •11 , relative density S1 •• I: 3.217, black solid crystalhzmg : in both hexagonal and cubic ~ forms, sublimes at 270~oC, ~ soluble in molten potassIUm ; hydroxide. A hard material used ~s ~ abra- ~ sive and refractory. SIC IS made I in an Acheson furnace carbon : and silicon are packed round a ~ core ofcarbon through w~~h a ~ large current is passed, raIsmg ; the temperature to around: 2000°C. (For les~. pure ~ samples, coke and sIhca are I
two atoms t?at inv?lves the sharing of a smgle paIr of electrons between the atoms. • Sir Humphrey Davy an English chemist, Sir Humphrey Davy (1778-1829) pioneered the study of Electrochemistry and isolated the elements sodium, potassium, mag_ nesium calcium, strontium and bariu~ by Electrolysis 1807AD-1808AD. He recognised that Chlorine was an element in 1810AD. His most practical invention was the Davy Lamp, a safety lamp used by miners in the pits.
; used. ) • silicon controlled rectifier : I . th a switching device;. 10 eon: state it has low reSIstance and ~ in the off state it has very high ; resistance.
• size exclusion chromatography where you separate mixtures based on the sizes of the molecules.
I • slaked lime • silver : Calcium hydroxide (or slaked Group 11 transition metal of ~ lime) Ca(OH)2' Me 74.09, the second series, symbol Ag I colourless hexagonal crystal, (from the Latin "argentum"), I relative density 2.24, mp Z = 47, Ar = 107.868. 580°C, decomposes before • single bond boiling. the single bond is the covalent ~ Dissolves sparingly in water to or coordinate bond between ~ form limewater. When carbon dioxide is bubbled through
1/ = = = = = = = = = = = = = = = Imn;tJlJnic Chemistry
II
171
slaked lime I smokeless powder
limewater, a white precipitate of calcium carbonate is produced this is used a diagnostic test for the gas.
~ of order in the arrangement of
; the molecules. Such substances : are known as liquid crystals and ~ they are characterised by opti-
~ cal anisotropy. ; Typical molecules which give slaked lime (i.e. calcium hy- : rise to liquid crystals have a high droxide), is prepared by adding ~ degree of asymmetry (long and water to freshly prepared quick- ; skinny or planar).
• slaked lime
lime. • SLAR single layer antireflection coatmg • smectic
: In nematic liquid crystals, the ~ molecular axes are ligned up in ~ the same direction without any ; 2 dimensional ordering. : Cholesteric and smectic liquid ~ crystals are composed of laya smectic phase is when the I ers of molecules with long molecules align themselves into ~ molecular axes parallel and a pseudo-crystalline lattice. : perpendicular to the planes, Liquid crystals are one example. ~ respectively.
• smectic crystal Liquid crystal most crystalline substances melt to give clear, isotropic liquids in which all the order of the crystalline state has been replaced by random motion of the molecules in the liquidstate. However, some crystals on heating achieve a turbid state in which the substance exhibits the properties of a liquid such as surface tension and viscosity, but also displays a high degree
; Cholesteric and nematic liquid : crystals can exhibit very large ~ optical activities; cholesteric I types often exhibit iridescent ~ colours due to dichroism. ; • smokeless powder : Cellulose nitrate (or nitrocellu~ lose) a highly flammable mateI rial formed by treating cellulose ~ (cotton or wood pulp, for ex: ample) with concentrated nitric ~ acid or concentrated nitric acid ; plus either sulphuric or phos: phoric acid. I
Inorganic Chemistry
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172
Sn I softening point
II
=================*
If the nitrogen content is over ~ • sodium sulphate 13%, then the material is ; Na 2504' white orthorhombic known as guncotton or smoke- crystals, relative density 2.67, less powder. mp 888°C. Use~ as ~ propellant or an ex- I Can be produced industrially by plosIve, III la~quers and for- I reacting magnesium sulphate merly for mOVIe fllm. with sodium chloride in solution • Sn followed by crystallization, or by tin Group 14 element, symbol the action of concentrated 5n (from the Latin "stannum"), I sulphuric acid on sodium chloI ride. Z = 50, Ar = 118.69. • Snell's law The decahydrate, Na 2 50 4 • . e . e d·be n. Sill ,= n2 Sill 2' escn s re- 10H20 is known as Glauber's fraction. I salt and is used as a laxative. I This is named after J.R. • soap Glauber (16041668). soap is a mixture of the sodium ~ salt of the fatty acids, which is ; • sodium thiosulphate obtained on hydrolysis of fats : sodium thiosulphate, Na2520 3, with sodium hydroxide. Glyc- I is a salt used in photography for erol is also obtained in this re- I the fixing of photographic action. plates. • sodium hydroxide I • soft water (or caustic soda or sodium hy- ~ water with relatively little disdrate) N aOH, Mr 40.00, white solved calcium and magnesium deliquescent solid, relative den- I ions (the ions which cause scum sity 2.130, mp 318.4°C, bp I and prevent a good lather be1390 dc. ing got up). A strong base. It can be manu- I facmred by adding quicklime to I • softening point sodium carbonate or using the the point at which a glass can Castner. be molded or worked. 1/ ================= Inorganic Chemistry
II
sol I solutions
173
*================ - sol a stable dispersion of either solids in liquids or solids in solids. _ solenoid a long coil of wire consisting of may loops; when current flows through it, the magnetic field resembles that of a bar magnet. - solid the state of matter in which the atoms or molecules are held together by forces which are so strong that the resulting structure is rigid.
~ - solubility of gases I
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a general property of gases is that they diffuse to fill the volume in which they are contained (i.e. they have neither fIxed shape or fIxed volume). Thus, gases which do not react with each other, are infInitely soluble in each other in all proportions, due to this power of diffusion. This behaviour is described by Graham's Law and by Dalton's Law of Partial Pressures.
:I - soluble : a substance is soluble in a liq- solubility ~ uid, ifit dissolves in that liquid. ; solubility is the quantity of sol- A liquid can also dissolve in anute that dissolves a given quan- : other liquid is it is miscible with tity of solvent to form a satu- ~ the liquid. rated solution, and is ex- :I - solute pressed in kilograms per ~ in a solution of two substances, meter cubed, moles per kilo- ; that which is present in the gram of solvent, etc. The solu- : smaller amount. See solution. bility of a substance in a given I solvent depends on tempera- :I - solutions ture. No simple general rela- : a solution is a mixture of a liqtion exists between solubility ~ uid, called as the solvent, with and temperature, so each case ; a gas, liquid or solid known as must be investigated sepa- : the solute. Solutions are hoI . d rately. Polar solutes are more : mogeneous mrxtures, an usu~ ally consist of a mixture of a soluble in polar solvents.
Inorganic Chemistry
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174
SOIU~ionsofelectrolYtes I spacequantisation
solid (i.e. the solute) and a liquid (i.e. the solvent). When a solution if formed, the molecules of the solute are evenly distributed amongst the molecules of the solvent. In a solution, there are interactions between the molecules of the solute and the molecules solvent, and this interaction is known as solvation. • solutions of electrolytes solutions of electrolytes are the electrically conducting solutions formed when salts are dissolved in water. The high electrical conductivity of the solution is due to the presence of ions from the dissociation of the salt. • solvation solvation is the interaction of ions of a solute with the molecules of the solvent. It occurs only with polar solvents. Solvation is the process that . causes ionic solids to dissolve in polar solvents. The energy released during solvation is sufficient to compensate for the lattice energy of the ionic crystal, in which the ions are arr~ged in the solid state.
II
solvent I a solvent is a liquid that has the I ability to dissolve, suspend or : extract other materials, without I chemical change to the material or solvent. Solvents make it possible to process, apply, clean I or separate materials. Water is I an inorganic solvent. Organic solvents include hydrocarbon solvents, oxygenated solvents I and chlorinated solvents . I •
space quantisation the restriction in the directions that an an angular momentum vector can take, given by the rule that the z component of the angular momentum (in units of h bar) must have maximum and minimum values equal to the value of the relevant angular momentum quantum number, respectively. Other allowed values are obtained by stepping from the larger value to the smaller in unit intervals. In the absence of a magnetic field, these states, differing only in the direction in which the angular momentum vector points, are degenerate. A magnetic field lifts this degeneracy since the energy of
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11...,.,================= Inorgllnic Chemistry
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space-charge effect I sphere
175
*================ interaction with the magnetic ~ • spectrum dipole moment associated with I the presentation of a wave phethe angular momentum is de- ~ nomenon as a function of the pendent on the angle between : frequency (or wavelength or the two vectors. ~ wavenumber or energy) of the • space-charge effect ~ wave. used to describe particle beam ; • spectrum of hydrogen aberrations, i~ arises fr~m the ~ the spectrum of hydrogen is natural repulsIon of partlcles of : obtained by an electrical dis. a G· b The like a .focused beam :I ch arge m ill charge; di . diffi elSSIer 'TI J.U e. ~ sperse, glvmg a use ~ spectrum contains four bright ~age. ; lines, due to atomic hydrogen • spatial coherence : and is used in calibrating-specI how much the waves are in step : troscopes and refractomeres. as they leave a laser cavity. ~ The principal lines in the spec• special theory of relativity ; trum of hydrogen are: a red 1) Thebasiclawsofphysicsare : line, H, at 656.2 nm (i.e. the same in all inertial reference ~ Fraunhofer's C), a blue line, ~ H, at 434.0 nm, a greenishframes. 2) Light propagates through ; blue line, H, at 486.1 nm, (i.e. empty space with a definite : Fraunhofer's F) and an indigo speed c independant of the ~ line, H, at 410.2 nm. speed ofthe source or observer. ~ • speed of sound • specific gravity the ratio of the density of a substance at 4 C to that ofwater at 4 C.
~ equal to the square root of the
; bulk modulus/density of the : medium. As temperature ~ rises, so does the speed of I sound.
• specific heat the amount of heat it takes for ~ • sphere a substance to be raised one ; radius=41t{r 2 ), volume=4/ : 31t(r3 ). degree C. I InorglJnic Chemistry
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""1""76=========SP""h,,,,m;laberration I spin quantum number
• spherical aberration the variation of focus with aperture in which a ray through the edge of the lens intersects the axis at a point other than the paraxial focus.
• s~n a source of angular momentum for atomic particl~. Early quantum the?ry pred~cted that an electron ill an orbItal ~ad an~1ar momentum due to Its orbItal motion and that this .angular momentum was q~tlsed and governed by the orbItal angular momenr.um quantum number (or aZImuthal quantum num~er! 1. Due ~o space quantlsatlon each orbItal would be (21 + 1) fold ~egenerat:. Howeve~, on ~et~iled analYSIS of a~omic emISSIon spectra, Pauli concluded that there must be a second source of electronic angular momentum. By analogy with classical physics, it was reasonable to attribute this to the "spin" of the electron. Experimental evidence for electron spin was provided by the experiment of Stern and Gerlach. They showed that the electron's spin angular mQmen-
I I
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tum had to have spin orbital angular momentum quantum number, s , equal to 1/2. Dirac eventually showed that spin emerges naturally from a solution of the relativistic Schrodinger equation. Nuclei can also possess spin. Whereas every electron has a spin of half, nuclei can have nuclear spin angular momentum quantum number, I , equal to zero or other integer factors ofl/2.· The spin of the nuclei gives rise to nuclear magnetic resonance spectroscopy and there is a corresponding technique, electron spin resonance spectroscopy, arising from electron spin. Photons have a spin angular momentum quantum number of 1. This is the origin of many spectroscopic selection rules. If a photon had no spin, there would be no optical activity. spin quantum number this spin quantum number, s relates to the spin on an electron. The spin may have one of two values, s = + 0.5. or s = 0.5. Each sub-orbital can accommodate two electrons, and
I • I
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II ================= Inorganic Chemistry
II spinel I standard SOlUtion.. the two electrons in each suborbital must have opposite spins. Allowing two electrons in each sub-orbital and the magnetic quantum, ml explains the number ofelectrons which can be accommodated in each suborbital.
~
; ~
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; ~
• spinel magnesium aluminate, MgAl 204·
:
• spin-spin coupling constant defines how much of an interaction you have between nuclei in a molecule. Gives rise to the fme structure in NMR.
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177
crystal field splitting. The relative placement of the d orbitals is difficult to determine, so it must be calculated. • standard heat of combustion the standard heat of combustion is the heat evolved when one gram mole of a substance is burned in oxygen.
~ • standard reference elec-
trode
~ a standard reference electrode : is required in all electrochemi~ cal measurements. I In the case of the determination ; of standard reduction poten• spontaneous reaction : tials, the standard reference a reaction that will proceed ~ electrode is the hydrogen halfwithout any outside energy. I cell. ; In the case of pH measure• sputtering allow a material into the vapor : ment, the standard reference phase to condense into a thin ~ electrode is the calomel elecI trode. film ~
• standard solution I a standard solution is one which ; contains a known weight of re• square planer : agent in a defmite volume of this involves the splitting of the ~ solution. d orbitals into more than two energy levels, this is due to the • sputtering see SPT
Inorganic Chemistry
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178
standard-state I stateproperty
/I
"""""""''''''''''''''''''''''''''''''''''''''''''''''===*
• standard state ~ may be obtained using Hess's the pure form of a substance at ~ Law. . . 1 bar pressure for any given ; When starch and lOdme cOI?e tur into contact, a deep blue plgtempera e. I ment is formed. Starch is of• starch (or amylum) ten used as an iodine indicaa polymeric carbohydrate m~de ~ tor in the form of starch soluof a mixture of varymg ~ tion which is prepared by boilamounts of two glucose po~y- ; ing a little starch with water mers amylose and amylopectm. : in a boiling tube and pouring (An approximate for~ula for ~ some of the product into boilstarch is often !?ilven as ~ ing water in a beaker (starch (C6H lOO s)x where x IS around ; is sparingly soluble in water). 100.) : The solution must be cooled I t is found in many green ~ before use as an indicator beplants as an energy storage ; cause the blue colour disapmedium, in tubers such as : pears on heating (and reappotatoes, in the roots o~veg- ~ pears on cooling). fu. etables like carrots, and m the I . lik' e nee, w heat .• . state nction h . seeds of grams ~ a function whose c ange m I '. 11 d d and b arey. Because it has no precise mo- I magrutude so e y epen s on lecular formula, its molar en- ~ the initial and final states of a thalpies of combustion and for- : process and nct on the route mation are not defmed, but its ~ taken. standard enthalpy of comb~- ~ • state property tion for 1 kilogram of matenal ; a state property is a quantity is 17480 kJ. : that is independent of how the From a knowledge of the en- ~ substance was prepared. Exthalpy of formation of carbon ~ amples of state properties are dioxide and water. and the en. altitude h I , pressure, volume, thalpyofcombustl?nofstarc , : temperature and internal ena figure for the kilogram en- ~ ergy. thalpy of formation of starch ;
II ================ lnorglJni& Chemistry
II
states ofmatter I steam reforming
179 *~~~~~~~"""'"
- states of matter the states of matter are the three forms (i.e. solid, liquid and gas) in which matter is observed to exist. A fourth state of matter (i.e. the plasma state) exists at very high temperatures, when all materials are decomposed into their elements and the electrons are stripped from these atoms to form the plasma.
~
reactivity of the intermediates ; is much greater than that of the : reactants. : _ steam
, I
: water in the vapour or gaseous ~ state. Since at 1 bar water boils ; at 373 K, steam is normally : thought of as "hot". In fact, the ~ scalding properties of steam are ~ enhanced by its anomalously ; large enthalpy of vaporization, - stationary phase : 40.66 kJ mol. So, not only does applies to chromatography and .~ the steam from the kettle scald is the solvent which does not' you because it's at 373 K, you move the 'bound surface wa- ~ get an extra dose of 40.66 kJ ter' on the paper on paper chro- : heat for every mole condensed. matography. ~ _ steam cracking - steady ~ state approximation (or station- ; ary state approximation) : used in kinetics to simplify the ~ mathematical treatment of ~ complex reactions (especially ; chain reactions) and consists of : .d . th ., CO~SI ermg . e concentraTIons : of mtermedlates . .as.constant.. .I The approXlmaTIOn IS good . . If ., the concentraTIons of the mter-: mediates are low and when the I : indUction period of the reaction ~ is short. Low intermediate con- . I centrations will ocur when the
steam cracking is the industrial process using steam at high temperature to break down high molecular weight hydrocarbons into smaller molecules. _ steam reforming c...
steam relormmg IS a process used to convert methane de. d Colrom naturaI gas mto . nve a lll1XtU. f b ·d re 0 car on monoXl e d h d h· h· h an Y rogen, w 1C IS t en used to synthesise organic chemicals. The reaction occurs at about 900 DC using a nickel ~ catalyst.
Inorganic Chemistry
================= II
*
""18"",O========="",Stern",, Gerlach experiment I strength ofacids
CH4 + H 2 0
==> CO +
/I
amounts of materials involved in a chemical reaction. The total quantity of reactants (i.e. the • Stern Gerlach experiment mass of the starting materials) Stern and Gerlach fired silver ~ must be equal to the total mass atoms through an inhomoge- : of the products of the reaction. neous magnetic field. The fact ~ that the silver atoms were split ; • stoichiometry of electrolyup into 2 beams showed that: sis I there must be a source of an- : the stoichiometry of electrolygular momentum in the atom ~ sis is described by Faraday's with spin angular momentum ; Laws of Electrolysis. quantllm number 1/2. Orbital : • stopband angular momentum, governed ~ t h · . f -fl . · al be . e pnmary regIOn 0 re ectIon by llltegr quantum num rs, l b ' f . . fiiI uld d d bl d - or a sorptIon 0 a rejectIon co not pro uce a ou y e- ; ter. generate state only (21 + 1) fold : degeneracies are possible ~ • stp through space quantisation of; standard temperature and presthe orbital angular momentum. : sure; corresponds to DC, 1 (The electronic configuration of ~ atm. a silver atom consists ofa single I • streamline 6s electron outside a closed shell ~ the path taken by any particle structure the net angular mo- : in a steady, laminar flow. mentum of closed shells/ ~ subshells is zero, so that the ; • strength of acids angular momentum properties the strength of acids is deterof the silver atom are deter- mined by the degree to which mined by the single outer elec- I they are ionised in aqueous sotron.) lution. For example, sulphuric acid which is a strong acid is • stoichiometry I fully dissociated, and all the stoichiometry is the quantitative displaceable hydrogen in the relationship between the I
3H2
I
I
II ================= Inorganic Chemistry
II
strtme ~ids I sub-orbitals
acid is present in solution as hydrogen ion. H 2S04 = = > H( +) + S04 100% as H( +) Similarly, the weak acids ethanoic acid is only partially ionised in solution, and only . I 59f f h approxImate y 0 o. t e dI~pl~ceable hy~rogen ~n the aCId IS present ill solution as hydrogen ion. CH3COOH ==> H(+) + CH3 COO( -) 5% as H( + )
181 ~
ecules of the solvent). Examples ; of strong electrolytes include : almost all salts, the caustic al~ kalis and the mineral acids in I dilute solutions. I • strontium . I group 2 element, symbol Sr, an : alkaline earth metal Z = 38 ~ Ar = 87.62. ' , . ~ • structural biology ~ abranchofbiologydedicatedto ; the study of the three dimen: sional structures of proteins and • strong acids I : other molecules to help underacids which dissociate fully on I stand the function of these molsolution e.g. HCI, HN0 3 , ~ ecules in the cell. H 2S04 , HCI03 • ~I • structure of crystals • strong acids and bases : the structure of crystals is destrong acids and bases are ac~ scribed in terms of the geomids and bases which are com~ etry of a unit cell of the crystal pletely dissociated in solution. ; structure. • strong electrolyte ~ • sublevel a strong electrolyte is a sub: one part of a leve~ each ofwhich stance which undergoes almost ~ can hold different numbers of complete dissociation into ions I electrons. in solution. Solution of a strong electrolyte consist almost en- I • sub-orbitals tirely of positively charged ions ; atomic sub-orbitals are the secand negatively charged ions, : tions of orbitals containing which are stabilised in solution ~ paired electrons of opposite by solvation (i.e. by being asso- I spin. Each atomic sub-orbital ciated with aggregates of mol- ~ can hold one pair of electrons. lnorglJnu; Chemistry
================ II
• substitution reactions along with addition and elimination, one of the fundamental classes of chemical reaction in which one atom or group is substituted for another.
~ • superfluid
; a fluid that flows without vis~ cosity (ex He-II) : • superhigh surface area I carbon any carbon which has a specific surface area greater than 2630 square meters per gram
• substrate a molecule acted upon by an
I
enzyme.
I •
I
• suicide substrate I an enzyme substrate that itself: is not toxic but that produces a ~ toxic metabolic product. I • superconductor a material which has no resistance to electricity. When passingcurrent through a superconductor, there is no loss of electrical power due to these materials.
superionic materials
materials which exist largely in the ion phase. These are extremely useful in making con-' ductors which work via ionic migration. supernatant when one has a solution from which a precipitate has been formed, the supernatant liquid is simply the remaining solution above the solid .
I •
I
I
• superoxide dismutase • supercriticalliquid a liquid which exists at tempera- a copper and zinc containing tures above the normal boiling ~ enzyme present in all oxygen point; this is brought about ~ using organisms that scavenges through high pressure. Reac- . free radicals and converts them tivity of solutes in these liquids into hydrogen peroxide and I oxygen. can be changed drastically with minor changes in temperature I • supersaturated solution and pressure. I a supersaturated solution is one in which too much solute has
II supersatumted vapour I syngas
183
*================ been dissolved in a solvent. As a rule, hot solvents can dissolve more solute than the same quantity of cold solvent, so that when a hot saturated solution is cooled, a supersamrated solution tends to form at lower temperatures. • supersaturated vapour a vapor which will spontaneously begin to condense in the presence of nucleation centers. • surface adsorption surface adsorption is the phenomenon whereby a substance is attracted to the surface of a material and becomes attached to that surface. The phenomenon explains the mechanism of action of catalysts and the mechanism of separation in chromatography. • surface area of solids the surface area of solids is area of the interface between the solid and the gas to which it is exposed. Surface area is an important factor in catalysis, as it is this surface area which is available to absorb gases, vapours or liquids. The chemi-
Inorganic Chemistry
~ cal reactions then take place on ; the surface of the catalysts.
; • surface tension : (gamma); the force F per unit ~ length L that acts across any line ~ in a surface, tending to pull the ; surface closed. ; • surfactant ~ a species that is active between : two phases. It accumulates at ~ the interface and changes the ; surface tension . ; • suspended solids : suspended solids are the par~ ticles of insoluble matter which ~ are present in natural waters ; and sewage effluents. The lat: terhavehighlevelsofsuspended ~ solids, which must be subjected I to treatment before discharge ~ to the aquatic environment. ; : ~ ; :
• symmetry symmetry is the property of a molecule, whereby the molecule has the same observed physical structure and appear~ ance when viewed from differ~ ent orientations in space.
~
• syngas ; a mixture of gases (largely car~ bon monoxide and hydrogen)
================= II
184
..
synthesis I tempomry hardness 1/
, that results from heating coal ~ - tern in the presence of steam. Can; transmission electron microsbe used as a fuel. copy. What you do is take the sample, grind it up, then place _ synthesis I an aqueous suspension of it on a synthesis is the name given : a grid where the electron mito a chemical reaction in which ~ croscope can get at it. a chemical compound is made. ~ . . - temperature _ synthesIs of ammoma I . . . . : temperature IS the thermody. rty hi h d fi the synthesIs of ammorua IS an I . . d'al namIC prope w c e mes Important m ustn process: th· al f C'. h fi' f h . I e mtern energy 0 a system. lor enc'. The absoIute scaIeof tempera. t e Ixmg 0 atmosp. rutr?gen, ther~by mak!n~ it ~ ture results from the physical ~vatlable for mcorporatIon I properties of gases. There are mto a range of other com- a number of other temperature scales in use. The Celsius Scale pounds. _ synthesis reaction I of Temperature uses the freeza synthesis reaction is a reaction I ing point and boiling point of in which an inorganic com- water as the two fixed points pound is formed directly by the ~ and assigns the val~es 0 and 100 combination of its elements. ~ to these fixed pomts, respec.. ; tively and divides the scale be- synthetic cheffilstry : tween them into 100 degrees. a branch of chemistry in which I _1_ : - temporal coherence . d . ch effilsts eVIse ways to mCU\.e I . specific compounds of interest : how much waves stay m step and/or develop new chemical ~ along a beam path reactions for this purpose. ~ - temporary hardness _ TDFS ; temporary hardness is that : fraction of the hardness of time-dependent fluorescence I shifts : water that is due to dissolved I calcium bicarbonate. Tempo-
II ================= lnorglJnic Chemistry
II
185
term I thermal pollution
*================ rary hardness is removed on ~ • tetrachloroethylene boiling, when the calcium bi- I chemical name of perchloroetcarbonate is converted to cal- ~ hylene. cium carbonate. ~ • theoretical plates • term : represents how many times you each compound or element in a ~ do a separation in puriftcation; chemical equation. ; can be uc;ed to describe column ~ chromatography, GC, or • termination : HPLe. termination is the fInal step in I a free radical mechanism that : • theories of catalysis results in the stopping of the ~ the theories of catalysis explain free radical reaction. Normally, ; the influence of the catalysts on termination occurs only after a ~ the rate ofa reaction by describsignilicant number of propaga- : ing the detailed mechanism by tion steps in the free radical pro- ~ which the catalyst is involved in cess have occurred. ; the steps of the chemical reac: tion. • tertiary alcohol I
tertiary alcohols are aliphatic alcohols in which the hydroxyl group [-OH] is attached to a tertiary carbon atom (i.e. a carbon atom which has no hydrogen atoms attached directly to it). • tertiary treatment tertiary treatment is tlle polishing process to which a sewage effluent is subjected after it has received secondary treatment in order to reduce further its nutrient content.
lnorglJ#u Chemistry
: • thermal motion I : chaotic, random motion ofmol~ ecules due to the temperature ~
• thermal neutrons I neutrons that have not been ~ slowed down and have reached : equilibrium with matter at ~ room temperature ~ • thermal pollution ~
thermal pollution is the in; crease in temperature of natu: ral waters resulting from the ~ discharge to these waters of hot
================= II
186
thermion~emission I thermogravimetricanalysis 1/
effluents from industrial and power plants. The higher temperatures reduce the concentration of dissolved oxygen in the receiving waters and promote eutophication.
or released during the course of I the reaction, is the heat of reaction. The heat of reaction (i.e. the change in the energy durI ing the course of a reaction) is expressed as dR, (i.e. "deltaH"), which has positive values • thermionic emission I for endothermic reactions and you can get a current to flow ~ negative values for exothermic from a heated filament to a reactions . The unit of heat is positive electrode in a vacuum; the joule. Another unit of heat this emission is simply electrons I which is widely used in thermoflowing from the fllament to I chemistry, the calorie (i.e. the the positive-electrode. amount ofheat required -to raise 1 g of water through 1 DC) • thermistor a substance which changes its I which is equal to 4.18 joules. resistance with temperature. I • thermocouple Those developed as infrared I two metals are put together side detectors are known as bolomby side when heated, one eters. metal expands more than an• thermochemistry I other due to differences in the thermochemistry is the investi- I coefficients of thermal gation of the transfer of energy exansion, and the strip bends. in the form of heat during the This can be used as a switch, as course of a chemical reaction, ~ in a thermostat. which are called the heats of ; • thermodynamics reaction. In every chemical reI the smdy of heat and energy action, there is a difference beflow in chemical reactions. tween the intrinsic energy in the I reactants and the intrinsic en- • thermogravimetric analysis ergy in the products. This en- when you heat a sample to obergy, which is either adsorbed I serve weight changes; used I
II =================;= Inorganic
Chemistry
II
thermopl4sticmateriall
time-ofjl{qh~ ~~~~~~~===18=7
when studying the loss of wa- I ~ ters of hydration or CO2 • : • thermoplastic material ~ thennoplastic materials are poly~ meric materials which can be repeatedly softened by heating and ; hardened again on cooling. ; . : • thermoplastics ~ plastics that can be softened ~y ; heating and return to theIr : original state on cooling. ~ • thermopneumatic detector when the radiation incident on a gas in a closed chamber increases the temperature and pressure of a gas, a ~ror on the cell wall moves. T~ movement is measured optlca.IIy, and can be used to determme the amountofradiationincidenton the cell. • thermosetting material thermosetting plastics are those rigid plastic which are moulded into shape at the time o~ manufacture (i.e. at the tIme of polymerisation) and they an extensively cross-linked structure. These plastics cannot be remoulded to another shape as their rigidity is due to the highly
Inorganic Chemistry
~ ~ ; : ~
~
; : ~ ; ~ ~
:
~
I
~
cross-linked structure formed between the molecules at the time of polymerisation . "Bakelite" is an example of a thermosetting polymer. • thermovoltaic detector an IR detector where temperature changes of a junction of dissimilar metals because of changes in the level of incident radiation causes a change in voltage. • Thomas Graham a British chemist, Thomas Graham (1805-1869) formulated Graham's Law of Gaseous Diffusion which states that the diffusion rate of a gas is inversely proportional to the square root of its density. He also discovered the colloidal state, while working on diffusion and osmosis. • time dilation the idea that time travels slower for somebody in a moving reference frame; consequence of relativity.
~ • time-of-flight : when you apply the same. trans~ lational energy to all partIcles;
==============~ II
188
titmtiun I transducer
II
==~~~====~~=.
the lighter particles will travel a shorter distance over a charged plate because there is less momentum to carry them forward. • titration
I I
I
I
• total internal reflection second harmonic generation
this is what happens when you shine the exitation beam and probe beam on a liquid-liquid surface. What you are counting on happening is that the beams will reflect o~ of the bottom liquid and give the second harmonic signal you're looking for.
titration's involves taking a I definite volume, usually 20 I ml, of a liquid whose concentration is unknown, and I slowly adding a solution of a I reagent with which the solution reacts, until reaction is • toxaphene complete. An indicator is used commercial name of an insectito denote the end-point of the I cide, a mixture of isomers obtitration. The volume of the I tained by chlorination of camsolution added is noted, and phene. It was used primarily to allows the concentration of ~ control insect pests on cotton the unknown to be calculated. I and other crops. It is classified • titration curve I as a POP. titration curves are the plots of ; • toxin pH versus the volume of re- a poisonous substance. agent delivered during the course of a titration. The inflec- I • transducer tion point in the titration curve a device that turns one kind of marks the end-point of the ti- energy to another (like a loudI speaker turns electrical energy tration. I to sound); a device that con• total binding energy verts a light signal into an elecenergy required to break a I trical signal nucleus into its component pro- I tons and neutrons
II ================= Intn;!JlJni& Chemistry
II
transforencenumber
I trichloroethYI~ ==========1=89
• transference number different ions carry different fractions of the current because different ions move at different speeds under the same potential gradient. The transference number of an ion is the fraction of the total current that is carried by that ion during electrolysis. In general, a cation and an anion differ in the amount of current they can carry during electrolysis. • transient grating techniques what you do in one of these studies is to get several beams coming into a sample that have different circular polarity. Their interference sets up a diffraction grating which can be used to run experiments.
~
• transition state I the activated form of a molecule ~ that has partly undergone a : chemical reaction. I
: • transverse relaxation time (t2) ~ the time it takes after a pulse in I NMR for the spins to get out ~ of phase with one another. : This is also called the spin-spin ~ relaxation time. ~
; ~
: ~
;
; • trepr ~ time-resolved electron para: magnetic resonance; a way of ~ identifying transient radicals ~
• tri ~ a prefIx meaning three.
• transistor a device used to give current and I power amplification ; : • transition elements elements that have incompletely ~ filled d subshells or readily give ; rise to cations that have incom- ; pletely filled d shells. ~
Inorganic Chemistry
• transverse wave when a wave has the property that the partiCles of the wave move perpindicular to the motion of the wave itself, such as a water wave.
triads the triads are the three groups of elements, each of three metals, in Group VII Elements of the periodic table. .
•
• trichloroethylene trichloroethylene is mainly used in the degreasing of met-
=================_11
190
trichroism I tungsten filament
II
also Under the VOC Directive, ~ Fats + Alkali = = > Soap + its use in that application is re- ; Glycerol stricted to enclosed systems in : Fats are triesters of glycerol, and all new installations; old instal- ~ when they are hydrolysed with lations will have to comply with ~ sodium hydroxide, yield glycstringent emission limits after ; erol, CH 2 (OH).CH(OH) April 2007. Trichloroethylene: .CH2 (OH), and soap, also is used to a much lesser ~ Rl COON a, which is a mixture extent in adhesive and aerosol ; of the sodium salt of the fatty formulations and as a chemical : acids. process intermediate in polyvi- ~ Glycerol is a by-product in the nyl chloride (PVC) and ~ soap industry and is recovered fluorochemical production. See ; by suitable means. other information and com- : _ triple bond ments under "Chlorinated Sol- ~ th . 1 bo d be bo vents". ; e tnp e n tween car n : atoms in alkynes involves a to• trichroism ~ tal of six electrons (i.e. three exhibits different colors in 3 dif- ; shared pairs of electrons). ferent directions when viewed : These bonds are formed in difby transmitted light. ~ ferent ways and the first bond _ trihydric alcohol ~ beha~e differently in chemical · al h 1 (. 11' I ) . reactions from the second and trihYdrlC. co 0 s l.e. no. s ~ third bonds. are organIc compounds contam- I ing three hydroxyl groups. The : - tungsten filament simplest trihydric alcohol is ~ an IR light source where the l,2,3-propane-triol, CH 2 ; emitter is a tungsten fila(OH).CH(OH).CH 2 (OH), ~ ment; the IR output range is which is also known as glycerol : limited by the window mate(from the Greek glykys mean- ~ rial, although the window ing sweet) or glycerin. Glycerol ; material may actually heat up is commercially produced by : enough to serve as a blackthe hydrolysis of Fats. ~ body emitter.
II ================ lnorglJnic Chemistry
1/ tunneling I vacuum ultraviolet (VUv~ =========="",19=1
_ tunneling ~ - ultraviolet radiation the penetration of a particle I the shorter wavelength spectral into a classically-forbidden re- ~ reg~on adjacent to the visible gIon. : regIon. I : _ uniphase - turbulent flow when a moving liquid exhib- ~ a wavefront is uniphase if it has its erratic, whirlpool-like cur- ~ the same phase at all points. rents. ~ - unsaturated compound - turing pattern ; an unsaturated compound is patterns that arise from oscil- : an organic compound in latory coupled cells. ~ which at least one bond beI tween the carbon atoms is a - two-dimensional NMR ; double or triple bond. These a method in which you can take NMR peaks that are : compounds tend to react with stuck on top of each other and ~ other compounds by undergoseparate them. The plot has ; ing addition reactions to form one axis as the normal NMR ~ saturated compounds. axis, and the other corresponds to the spectrum when you hit the sample with 90 degree radiation. -1Yndall effect the scattering of visible light by a colloidal dispersion.
:I - unsaturated solution : an unsaturated solution is a ~ solution which contains less ; than the maximum amount of ~ solute that can be dissolved in : the solvent at that tempera~ ture. If added, more solute ; will dissolve in an unsaturated : solution.
- UHV I ultrahigh vacuum. : - vacuum ultraviolet (vuv) I _ ultrasonic : U V radiation of high enough sound waves that have fre- ~ frequency that air will absorb quency higher than we can hear ; it. UHV is ultrahigh vacuum(20,000 Hz). lnora_i& Chemistry
================ /I
192
valence electrons I JiJn tier Waal's force
II
==============~*==============
UV which is of higher fre- I lecular attraction and the vol, till umes occupied by the gas molquency s . ecules . • valence electrons the electrons in the outermost ; • Van der Waal's force shell of an atom. the Van der Waal's Force is the I attractive force between mol• valency I ecules which is caused by the valency is the combining power : induc~d temporary polarisation of an element (i.e. the number ~ of molecules by the dipole moof bonds which the atom can; ments of molecules. form with other atoms). Va- : In complex covalent comlency is governed. by the num- ~ pounds, an attraction occurs ber of electrons m the outer- ~ between the protons ')f one most electronic shell of the at- ; molecule and the electrons of oms of that element (i.e. the : another. As two molecules of valency electrons). These va- ~ the compound approach one lency electrons are given ~p to ; another, the electrons in the other atoms or are recelve.d ~ outer shells of both molecules from other atoms to make Ioruc : which have a negative charge Bonds, or the valency electrons ~ begin to repel each other. When are shared with other atoms to ; the molecules are a certain dismake {}}valent Bonds. The pro- : tance apart the forces of attrac. eIectr<:>ns I d cess of transfernng : tion and' repulsion are equal an between atoms or of sharmg ~ opposite (i.e. the forces are balelectrons between atoms results . anced at that distance). in the formation of~mpounds, I Graphite, which is a crystalline where the atoms m the com- I form of carbon, consists of flat pound achieve the ~table elec- planes of carbon atoms. The tronic configuratIOn of the carbon atoms in each plane are I held together by covalent Nobel Gas elements • Van der waals equation I bonds. However, there are no an equation for non-ideal gas- I covalent bonds between the ses that accounts for intermo- planes, and the only forces be-
II ================== Inorganic Chemistry
II
Vattderwaals picture ofumdmsed
ma:=1"",vi"",ta"",lforc="",C======"",19=3
tween the planes are the weak ~ - velocity intermolecular interactions (i.e. ; speed of an object; the change the Van der Waal's Force). The ~ in position over time. planes can slip and slide over ~ _ velocity selector d·th 1 ul be each other with ease, a fact · h h I I· h : use WI mo ec ar ams; h e ps to exp am w y l I d di ks tha _1nl w 1C ft d d I . s otte s tm
,
I
blO1lJanic Chemistry
-- II
194
voltage lwaterpollution "
==============~.
erties oflife in the organic com- ~ pounds found in animals and; plants. Wohler's synthesis of : . compound, :I urea an orgamc from the inorganic compound, ~ ammonium cyanate discredited ; the theory of the existence of a vital force. ~ ; • voltage ; equal to the potential difference . between two things. I
• voltaic cell voltaic cells are the electrochemical cells that are constructed to be a source of electric current to power external devices.
ods of titrating various pairs of solutions, one against the other, and with the calculations arising from such titration's. In the case of gases, the main technique involves reacting or absorbing gases in graduated containers over mercury, and measuring the volume change during the course of reaction. .vom
volt-ohm-meter; a multimeter ~ that measures voltage, current
; and resistance. Walden reductor ~ a metal reduction column filled : with silver. I •
• Walsh diagram • volume measures the size of an object ~ a diagram that shows the variausing length measurements in I tion of orbital energy with mothree dimensions. : lecular geometry. • volumetric analysis volumetric analysis is the quantitative analysis of liquids and gases. In the case of liquids, the concentration of a solution of unknown strength is determined by causing the solution to react with another solution of known concentration. Volumetric analysis is mainly ooncemed with meth-
; • water water, ~O, covers three quar~ ters of the surface of the globe, ~ and is a prereq~ite for the ex; istence of life as we know it on : Earth. It is the most important ~ solvent. ; • water pollution I
water pollution is the degradation of the quality of water re-
II =================
lnorgllni& Chemistry
1\ waterresources I weak bases
195
sources as a result of physical, ~ chemical or biochemical prochemical and/or microbiologi- ; cess, to render it suitable for a cal contamination. In general, ~ specific use. polluted surface waters result: For example, water must unwhen water contains either too ~ dergoes treatment to render little dissolved oxygen, or too ; it suitable for use as drinking high a concentration of toxic: water. substances, such that they can- ~ • wave not support living organisms. I . I h' h The most common causes of : a slgna w lC propagates ~ through space, much like a wawater pollution are the dis; ter wave moves through water. charge of untreated treated domestic sewages, detergents and ; • wavelength industrial trade effiuents from : on a periodic curve, the length b ' point sources to rivers and l : etween two consecutive streams, the presence of nutri- ~ troughs (low points) or peaks ents, fertilisers and pesticides in ; (high points). the diffuse run off from agri; • wavelength of light cultural sources to ground wa: the wavelength of light is the ters and surface waters, and the presence of oils, contaminated ~ distance between successive suspended solids in the storm I crests of the transverse electrowater runoff from urban areas ; magnetic wave. The wavelength : of each colour of visible light is to surface waters. ~ different. • water resources ~ • weak acid water resources are the bodies of water which are avail- I substances capable of donating able for exploitation for ben- ~ hydrogen but do not completely : ionise in solution. eficial purposes. I : • weak bases • water treatment water treatment is the purifica- ~ substances capable of accepting . tion of water, by a physical, I hydrogen but do not completely ; ionise in solution. Inorganic Chemistry
================= II
196
wedgeprism I Zeeman effect
II
~=======*
• wedge prism used for beam steering. • Welsbach mantle a gauze mesh, simila~ to the one in gas lanterns, Impregnated with Th0 2 and a.sm~ll amount of Ce0 2 which IS he;u:ed by either a burning gas or electric clJarge. It gives off IR radiation between 10-1 00 microns. • Werner Karl Heisenber~ . a German mathematic~ phySlcist, Werner Karl Heisenberg (1901-1976) is the Fath~r of Quantum Mech~ics. He 1~ remembered for his U ncertamty Principle, that rej~cts the notion that the propertIes of an atom can be descnbed exactly by the solutions to mathematical matrices.
~ • x-ray fluorescence spec; troscopy (xci) : measures the energies of the ~ inner electrons of an atom by ~ knocking them off with X. rays' good for about 35 ele~ men~. Handybecauseitisnot ~ a destructive method of analy; sis _the electrons are simply el: evated to outer orbitals and the ~ relaxation to the inner orbitals ~ is measured.
~. yield of a chemical reaction ; : ~ ~ .
the yield of a chemical reaction is the percentage of the calculated stoichiometric quantity of the principal produce ~hich was obtained in the reaction. Few ~ organic reactions give 9uantita~ tive yield (i.e. 100% yIeld) of a I single product. . ; • Young's modulus :I the ratio of longitudinal stress • • • Winkler titr~t1on.. : to longitudinal strain. the Winkler tltratlOn IS the I £Ii " d d t : .Zeemane ect back tltratlOn use to e er- I . . . mine the concentration of Dis- : this IS the effect of overcommg solved Oxygen in a sample of ~ the normal degeneracy o~elec; tron spin states h' by happlymg . a water. ld : magnetic fie w 1C can mter• work ~ act with the magnetic moment expression of the movement of ; of the electron. This is oban object against some force. 11 __================ Inorganic Chemistry
II
zeroth law ofthermodyamics I Zirconi; tetrachloride
197
served when atoms are sub- ~ medicine, and to make piezojected to a powerful magnetic ; electric crystals. Also known as field resulting in the spectral : zirconia; zirconic anhydride; lines being split into a number ~ zirconium dioxide. of component lines. ~ • zirconium oxYchloride • zeroth law of ~ ZrOCI2.8H20, 'white crystals thermodyamics ; that are soluble in water, inif A is in thermal equilibrium : soluble in organic solvents, and with Band B is in thermal equi- ~ acidic in aqueous solution; used librium with C, then A and C ~ for textile dyeing and oil-field are in thermal equilibrium. ; acidizing, in cosmetics and • zirconium hydroxide ~ greases, and for antiperspirants . h -. and water repellents. Also· Z r (OH) 4' a toXIC, amorp ous . kn b·· . hi · . I bl . I own as aslC zrrcoruum c oI hi ·d w hitepowd er,msou emwa- · · d · . dil . al· n e; zlrcony c on e. ter, soIu ble mute mmer I acids; decomposes at 550°C; ~ • zirconium phosphate used in pigments, glass, and : ZrO(H2P04)2.3H20, a toxic, dyes, and to make zirconium ~ dense white powder that is incompounds. i soluble in water, soluble in ac• zirconium nitride : ids and organic solvents; de~ composes on hearing; used as ZrN, a hard, brassy powder that is soluble in concentrated ~ an analytical reagent, coagulant, ; and radioactive-phosphor caracids; melts at 2930°C; used in : rier. Also known as basic zircorefractories, cermets, and labo~ nium phosphate; zirconium Ofratory crucibles. ~ thophosphate. • zirconium oxide ; • zirconium tetrachloride zr02' a toxic, heavy white pow~ ZrCI4, toxic, alcohol-soluble, der that is insoluble in water, : white lustrous crystals; subsoluble in mineral acids; melts ~ limes above 300°C and decomat 2700°C; used in ceramic ; poses in water; used to make glazes, special glasses, and ~ pure zirconium and for waterInorganic Chemistry
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zone t'tfining I zone refining
198
repellent textiles and as an analyrical reagent. Also known as zirconium chloride. • zone refining a technique used for reducing the level ofimpurities in certain
I
I
I
I
II
metals, alloys semiconductors, and other materials. It is based on the observation that the solubility of an impurity is generally different in the liquid and solid phases of a material.
II ================= Inorganic Chemistry
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Notes
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