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ChemistryinQuantitativeLanguage
CHEMISTRYINQUANTITATIVELANGUAGE
FundamentalsofGeneralChemistryCalculations
ChristopherO.Oriakhi,CChem,FRSC
GreatClarendonStreet,Oxford,OX26DP, UnitedKingdom
OxfordUniversityPressisadepartmentoftheUniversityofOxford. ItfurtherstheUniversity’sobjectiveofexcellenceinresearch,scholarship, andeducationbypublishingworldwide.Oxfordisaregisteredtrademarkof OxfordUniversityPressintheUKandincertainothercountries ©ChristopherO.Oriakhi2021
Themoralrightsoftheauthorhavebeenasserted FirstEditionpublishedin2009 SecondEditionpublishedin2021
Impression:1
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ISBN978–0–19–886778–4
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Preface
Thisisthesecondeditionof ChemistryinQuantitativeLanguage.Iampleasedthatthefirst edition,publishedin2009,wassowellreceivedbybothinstructorsandstudents.However,asis typicalwithmostbooksintheirfirstedition,theusersgraciouslyprovidedseveralconstructive suggestionstomakethebookmoreusefulfortheintendedaudience.Inaddition,onmypart,a decadelaterIfindtheneedtoaddafewtopicsandconceptsthatwereleftoutofthefirstedition,as wellastheneedtoreorganizethechaptersandupdatetheworkedexamplesandend-of-chapter problemstomakethebookmoreuseful.Allofthesehavearmedmewiththemotivationand insightsnecessarytopreparethissecondedition.Formulatingandsolvingquantitativechemistry problemsremainsaconcernformanystudents.Thiseditionsharesthesameobjectiveofmaking problem-solvinginchemistrymorepleasurableandexciting,sostudentscanhopefullyfacetheir examinationswitheaseandpasswithflyingcolors.
Thissecondeditionhasbeenrevisedextensivelyandincorporatesmanyminorchangesthan canbeincludedhere.Themostsignificantchangesinclude:
•Theoriginalfirsttwochapters(EssentialMathematicsandSystemofMeasurement)have beenremovedandmadeavailableintheAppendix.
•Ihaveaddedprincipalnewmaterialsbrokendownintotwonewchapters(Chemical Bonding1:BasicConcepts,andChemicalBonding2:ModernTheoriesofChemical Bonding)asthesearefoundationalcollegechemistrymaterials;thelatterchapterdeals specificallywithmolecularshapesandstructure.
•ThroughoutthebookIhaveaddednewproblemswithvaryingdegreeofdifficulties,while othershavebeencombined,revised,orreplaced.
ThroughoutthebookIhaveadheredtothephilosophybehindthefirstedition,whichwasto introducetheconceptsoftheunderlyingchemistryfollowedbyaseriesofworkedexampleto showstudentshowthecalculationsaredoneandtohopefullyenablethemtoappreciatewhat isinvolved.Attheendofeachchapterareaseriesofproblemsthatrangefromverysimpleto thoserequiringmoretimeandenergy.Eachprobleminthebookhasbeensolvedandchecked independentlybyTedLaPage.AnswersforalltheproblemsareintheSolutionstoProblems chapterattheendofthebook.
Ifyouhaveusedthisbookandfoundanyerrorsorhavecomments,suggestions,and recommendationsforfuturerevisionsandadditions,pleasefeelfreetoreachouttomebyemail atoriakhi@gmail.comorbycontactingOxfordUniversityPress.
Acknowledgement
PreparationofthesecondeditionofChemistryinQuantitativeLanguagebenefitedgreatlyfrom theimmensesupportandencouragementofmyfamilyandsomeamazingfriends,colleagues, andstudents.
IbeginbyexpressingmysincereappreciationtoTedLaPageforhisindispensablecontributionstothisedition.Inadditiontohisgreatsenseofhumor,dedication,andfriendship,Tedread theentiremanuscript,solvedtheproblems,andsuggestedmanyimprovementsinbothcontent andstyle.
Suggestionsandconstructivefeedbackfromstudentsandfacultywhohaveusedthebookare particularlyhelpfulanddeeplyappreciated.Manyofyoursuggestionshavebeenincorporated intothisrevision.
IalsothankthevariouspersonsatOxfordUniversityPressespeciallyKatherineWard,Sonke Adlung,andHarrietKonishifortheirdedicationandfriendlysupportingettingthisprojectto thefinishlineinarecordtime.
Finally,thisacknowledgementwouldbeincompletewithoutsayinghowmuchIappreciate thelove,patience,support,andencouragementIreceivedfrommyfamilyandfriendsatalltimes. Inparticular,Idedicatethiseditiontothememoryofmother,MrsIkhiwiOriakhi,whoinspired thiswork.
6ChemicalEquations
6.3TypesofChemicalReactions46 6.4Problems48
7Stoichiometry
7.1ReactionStoichiometry50
7.2InformationFromaBalancedEquation50
7.3TypesofStoichiometricProblem50
7.4LimitingReagents57
7.5ReactionYields:Theoretical,Actual,andPercentYields59 7.6Problems60
8StructureoftheAtom
8.1ElectronicStructureoftheAtom64
8.2ElectromagneticRadiation64
8.3TheNatureofMatterandQuantumTheory66
8.4TheHydrogenAtom67
8.5TheQuantum-MechanicalDescriptionoftheHydrogenAtom70
8.6QuantumMechanicsandAtomicOrbitals71
8.7ElectronicConfigurationofMultielectronAtoms75
8.8Problems78
9ChemicalBonding1:BasicConcepts 81
9.1Introduction:TypesofChemicalBonds81
9.2LewisDotSymbols81
9.3IonicBonding:FormationofIonicCompounds83
9.4CovalentBonding:LewisStructuresforMolecules86
9.5CovalentBonding:WritingLewisStructures86
9.6ResonanceandFormalCharge88
9.7ExceptionstotheOctetRule91
9.8PolarCovalentBonds:BondPolarityandElectronegativity93
9.9Problems98
10ChemicalBonding2:ModernTheoriesofChemicalBonding
10.1VSPERTheory:MolecularGeometryandtheShapesofMolecules102
10.2VSEPRTheory:PredictingElectronGroupGeometryandMolecularShape withtheVSEPRModel103
10.3VSEPRTheory:PredictingMolecularShapeandPolarity107
10.4ValenceBondTheory110
10.5ValenceBondTheory:TypesofOverlap111
10.6Hybridization112
10.7LimitationsofValenceBondTheory119 10.8MolecularOrbitalTheory120 10.9Problems125
11GasLaws 129
11.1StandardTemperatureandPressure129
11.2Boyle’sLaw:VolumevsPressure129
11.3Charles’sLaw:VolumevsTemperature130
11.4TheCombinedGasLaw132
11.5Gay-Lussac’sLawandReactionsInvolvingGases134
11.6Avogadro’sLaw136
11.7TheIdealGasLaw137
11.8DensityandMolecularMassofaGas139 11.9MolarVolumeofanIdealGas140
11.10Dalton’sLawofPartialPressure142
11.11PartialPressureandMoleFraction143
11.12RealGasesandDeviationfromtheGasLaws144
11.13Graham’sLawofDiffusion146
11.14Problems148
12LiquidsandSolids 152
12.1TheLiquidState152
12.2VaporPressureandtheClausius–ClapeyronEquation152 12.3TheSolidState155
12.4TheCrystalSystem156
12.5CalculationsInvolvingUnitCellDimensions159
12.6IonicCrystalStructure165
12.7TheRadiusRatioRuleforIonicCompounds167
12.8DeterminationofCrystalStructurebyX-RayDiffraction171
12.9Problems174
13SolutionChemistry 177
13.1SolutionandSolubility177
13.2ConcentrationofSolutions178
13.3SolvingSolubilityProblems188
13.4EffectofTemperatureonSolubility191
13.5SolubilityCurves191
13.6EffectofPressureonSolubility193 13.7Problems194
14VolumetricAnalysis 199
14.1Introduction199
14.2ApplicationsofTitration199
14.3CalculationsInvolvingAcid-BaseTitration200 14.4BackTitrations206
14.5KjeldahlNitrogenDetermination210 14.6Problems212
15IdealSolutionsandColligativeProperties 214
15.1ColligativeProperties214
15.2VaporPressureandRaoult’sLaw214
15.3ElevationofBoilingPoint217
15.4DepressionofFreezingPoint220
15.5OsmosisandOsmoticPressure222
15.6Problems225
16ChemicalKinetics 228
16.1RatesofReaction228
16.2MeasurementofReactionRates228 16.3ReactionRatesandStoichiometry233 16.4CollisionTheoryofReactionRates234 16.5RateLawsandtheOrderofReactions235
16.6ExperimentalDeterminationofRateLawUsingInitialRates236
16.7TheIntegratedRateEquation240
16.8Half-LifeofaReaction246
16.9ReactionRatesandTemperature:TheArrheniusEquation248 16.10Problems250
17ChemicalEquilibrium 255
17.1ReversibleandIrreversibleReactions255
17.2TheEquilibriumConstant255
17.3TheReactionQuotient259
17.4PredictingtheDirectionofReaction259
17.5PositionofEquilibrium260
17.6HomogeneousvsHeterogeneousEquilibria261
17.7CalculatingEquilibriumConstants262
17.8CalculatingEquilibriumConcentrationsfrom K 263
17.9QualitativeTreatmentofEquilibrium:LeChatelier’sPrinciple268 17.10Problems273
18IonicEquilibriaandpH 276
18.1TheIonizationofWater276 18.2DefinitionofAcidityandBasicity276
18.3ThepHofaSolution277
18.4ThepOHofaSolution278
18.5TheAcidIonizationConstant, Ka 280
18.6CalculatingpHandEquilibriumConcentrationsinSolutionsofWeakAcids280 18.7PercentDissociationofWeakAcids283
18.8TheBaseDissociationConstant, Kb 285
18.9RelationshipBetween Ka and Kb 286 18.10SaltHydrolysis:Acid–BasisPropertiesofSalts288 18.11TheCommonIonEffect292
18.12BuffersandpHofBufferSolutions293 18.13PolyproticAcidsandBases298 18.14MoreAcid–BaseTitration301 18.15pHTitrationCurves303 18.16Problems308
19SolubilityandComplex-IonEquilibria 313 19.1SolubilityEquilibria313
19.2TheSolubilityProductPrinciple313 19.3Determining Ksp fromMolarSolubility314
19.4CalculatingMolarSolubilityfrom Ksp 316
19.5 Ksp andPrecipitation318
19.6Complex-IonEquilibria320 19.7Problems323
20Thermochemistry 325 20.1Introduction325 20.2CalorimetryandHeatCapacity325 20.3Enthalpy327
20.4Hess’sLawofHeatSummation331 20.5LatticeEnergyandtheBorn–HaberCycle333 20.6BondEnergiesandEnthalpy335 20.7Problems338
21ChemicalThermodynamics 344
21.1DefinitionofTerms344
21.2TheFirstLawofThermodynamics344 21.3ExpansionWork345 21.4Entropy348
21.5TheSecondLawofThermodynamics348 21.6CalculationofEntropyChangesinChemicalReactions348 21.7FreeEnergy352 21.8TheStandardFreeEnergyChange352 21.9EnthalpyandEntropyChangesduringaPhaseChange355
21.10FreeEnergyandtheEquilibriumConstant356
21.11Variationof G0 andEquilibriumConstantwithTemperature358 21.12Problems361
22OxidationandReductionReactions 365 22.1Introduction365
22.2OxidationandReductioninTermsofElectronTransfer365
22.3OxidationNumbers(ON)366
22.4OxidationandReductioninTermsofOxidationNumber368
22.5DisproportionationReactions369
22.6OxidizingandReducingAgents369
22.7Half-CellReactions371
22.8BalancingRedoxEquations372
22.9Oxidation-ReductionTitration381 22.10Problems385
23FundamentalsofElectrochemistry 389 23.1GalvanicCells389
23.2TheCellPotential389
23.3StandardElectrodePotential390
23.4TheElectrochemicalSeries(ECS)391
23.5ApplicationsofElectrodePotential391
23.6CellDiagrams393
23.7Calculating E 0 cell fromElectrodePotential394
23.8RelationshipoftheStandardElectrodePotential,theGibbsFreeEnergy, andtheEquilibriumConstant396
23.9DependenceofCellPotentialonConcentration(theNernstEquation)399
23.10Electrolysis402
23.11Faraday’sLawsofElectrolysis402 23.12Problems408
24RadioactivityandNuclearReactions 412
24.1Definitions412
24.2RadioactiveDecayandNuclearEquations412 24.3NuclearTransmutations415
24.4RatesofRadioactiveDecayandHalf-Life416
24.5EnergyofNuclearReactions419 24.6Problems423
AppendixA 427
A.1Essentialmathematics427
A.2Significantfiguresandmathematicaloperations428
A.3Scientificnotationandexponents429
A.4Logarithms432
A.5Algebraicequations434
B.1Systemsofmeasurement445
B.2Measurementofmass,length,andtime446
B.3Temperature447
B.4Derivedunits448
B.5Densityandspecificgravity449
B.6Dimensionalanalysisandconversionfactors451
AtomicStructureandIsotopes
1.1AtomicTheory
In1808,basedonexperimentaldataandchemicallawsknowninhisday,Daltonproposedhis theoryoftheatom.Thetheorystatesthat:
1.Allchemicalelementsaremadeupoftinyindivisibleparticlescalledatoms.
2.Atomscannotbecreatedordestroyed.Chemicalreactionsonlyrearrangethe way thatthe atomsarecombined.
3.Atomsofthesameelementareidenticalinallrespectsandhavethesamemassesand physicalandchemicalproperties.Atomsofdifferentelementshavedifferentmassesas wellasdifferentphysicalandchemicalproperties.
4.Acombinationofelementstoformacompoundoccursbetweensmall,whole-number ratiosofatoms.
Dalton’stheoryresultedintheformulationofthelawofconservationofmassandthelaw ofmultipleproportions.Alongwiththelawofdefiniteproportionandthelawofreciprocal proportion,theseformthebasisofreactionstoichiometry(seeChapter7).
1.1.1Thelawofconservationofmass
Inachemicalreaction,matterisneithercreatednordestroyed.Thetotalmassofreactantsisequal tothetotalmassoftheproducts.ThislawwasfirststatedbyLavoisier,basedonhisfindings fromcombustionexperiments.
1.1.2Thelawofdefiniteproportion
Thelawofdefiniteproportions(alsoknownasProust’slaworthelawofconstantcomposition) statesthatagivenchemicalcompoundisalwayscomposedofthesameelementsinthesame proportionsbymass.Whenelementscombinetoformaparticularcompound,theydosoin fixedandconstantproportionsbymass,regardlessofthesourceofthecompound.Forexample, asampleofpurewater,regardlessofitssource,alwayscontains11.1%hydrogenand88.9% oxygen.
1.1.3Thelawofmultipleproportions
Iftwoelementscanformmorethanonecompoundbetweenthem,themassesofoneelement, whichcombinewithafixedmassofthesecondelement,areinaratioofwholenumbers.For example,nitrogenandoxygencombinetoformcompoundssuchasNO,NO2 ,andN2 O,inwhich theratioofnitrogenatomsperoxygenatomisrespectively1,½,and2.Thisisoneofthebasic lawsofstoichiometry,aswediscussinChapter7.
1.1.4Thelawofreciprocalproportions
AccordingtotheLawofReciprocalProportions(alsoknownasthelawofequivalentproportions orthelawofpermanentratios),iftwodifferentelements,AandB,chemicallycombine separatelywithafixedmassofathirdelement,D,theratioofthemassesinwhichtheydo soareeitherthesameasorasimplemultiple(orsimplefraction)oftheratioofthemassesin whichAandBcombinewitheachother.Forexample,carbonreactswithsulfurtoformcarbon disulfide(CS2 )andwithoxygentoformcarbondioxide(CO2 ).Sulfurandoxygen,meanwhile, combinetoformsulfurdioxide(SO2 ),inwhichtheratioofsulfurtooxygenis1:2,whichis½ the1:1ratioofsulfurtooxygeninthecarboncompounds.
1.2TheStructureoftheAtom
Anatomconsistsofacentralnucleus,whichcontainsroughly99.9%ofthetotalmassofthe atom,andasurroundingcloudofelectrons.Thenucleusiscomposedoftwokindsofparticles, protonsandneutrons,whicharecollectivelyknownasnucleons.Theprotonispositivelycharged, whiletheneutroniselectricallyneutral.Theelectronshaveanegativechargeandsurroundthe nucleusin“shells”ofdefiniteenergylevels.(Note:energylevelisdiscussedinChapter8.)In aneutral(unreacted)atom,thenumberofelectronsequalsthenumberofprotons,sotheatom hasachargeofzero.Itmustbementionedthatthechemistryofagivenatomcomesfromits electrons;allchemicalchangestakeplaceentirelywithregardtotheelectrons—thenucleus isneveraffectedbychemicalreactions.Thepropertiesofthethreesub-atomicparticlesare summarizedinTable1.1.
1.2.1Atomicnumber(Z)
Theatomicnumberofanelementisdefinedasthenumberofprotonsinthenucleusofanatom oftheelement.Itisalsoequaltothenumberofelectronsinaneutralatom.Atomicnumberisa characteristicofagivenelementanddeterminesitschemicalproperties.
Table1.1 Propertiesofsubatomicparticles
FundamentalparticleSymbolLocationMass(g)Mass(amu)Charge
1.2.2Massnumber(A)
Themassnumberofanelementisthesumofprotonsandneutronsinthenucleusoftheatom.
Massnumber (A) = No. ofprotons (Z) + No. ofneutrons (N) A = Z + N
Thegeneralsymbolforanelement,showingitsmassnumberandatomicnumber,is:
A = massnumberinatomicmassunits (amu)
Z = atomicnumber
E = symboloftheelementasshownontheperiodictable
Forexample,thesymbolsforCandMg,showingtheirmassandatomicnumbers,are: 12 6 Cand 24 12 Mg
1.2.3Ions
Anionisanatomorgroupofatomsthathasgainedorlostelectron(s).Apositivelycharged ionresultswhenanatomlosesoneormoreelectrons.Conversely,anegativelychargedionis formedwhenanatomgainsoneormoreelectrons.Forexample,asodiumatom,Na,losesone electrontoformasodiumion,Na+ ;anitrogenatom,N,gainsthreeelectronstoformanitrogen (ornitride)ion,N3 . Letustrytodeterminethenumberofprotons,electrons,andneutronsintheCa2+ ion.A neutralCaatomhastwentyelectronsandtwentyprotons(atomicnumber = 20).ACa2+ ion however,hastwentyprotonsandeighteenelectrons(foranetchargeof +2).Themassnumber, whichisthesumofprotonsandneutrons,isforty;sincetheionhastwentyprotons,itmusthave 40–20 = 20neutrons.
Example1.1
Determinethenumberofprotons,neutrons,andelectronsin
(a) 23 11 Na (b) 16 8 O2 (c) 56 26 Fe3+ (d) 63 29 Cu
Solution
Thesolutionsaresummarizedinthefollowingtable.
SymbolProtonsNeutronsElectrons
(a) 23 11 Na111211
(b) 16 8 O2 8810
(c) 56 26 Fe3+ 263023
(d) 63 29 Cu293429
Example1.2
Completethefollowingtable.
ParticleAtomicMassNumberofNetchargeSymbolEn± numbernumberprotonsneutronselectrons
Tocompletethistable,youneedtorecallthebasicdefinitionsandthegeneralequation:Mass number(A) = No.ofprotons(Z) + No.ofneutrons(N).Usetheperiodictabletoidentify thecorrespondingsymbols.Alsorememberthatatomicnumberisequaltothenumberof protonsinthenucleusofanatom.Inaneutralatom(zerocharge),thenumberofelectronsis alwaysequaltothenumberofprotons.Thedifferencebetweenthenumberofprotonsandthe numberofelectronsisthechargeontheatomicparticle.Ifthenumberofprotonsisgreater thanthenumberofelectrons,theparticletakesonanetpositivecharge,andvice-versa.The completetableis
ParticleAtomicMassNumberofNetchargeSymbolEn± numbernumberprotonsneutronselectrons
1.3Isotopes
Isotopesareatomsthathavethesameatomicnumber,andhencearethesameelement,butthat havedifferentmassnumbers(thatis,differentnumbersofneutrons).Thedifferenceinmassis duetothevariationintheneutronnumber.Isotopeshavepracticallythesamechemicalproperties butdifferslightlyinphysicalproperties.Mostelementsexhibitisotopy.Forexample,hydrogen hasthreeisotopes:hydrogen,deuterium,andtritium.Theatomicnumbersandmassnumbersare showninTable1.2.
Table1.2 Thehydrogenisotopes
Hydrogen(H)Deuterium(D)Tritium(D)
Atomicnumber111
Massnumber123
Example1.3
Whichofthefollowingareisotopes?
a) 18 9 Fand 18 10 Ne
b) 2 1 Hand 3 1 H
c) 40 19 Kand 40 20 Ca
d) 24 12 Mgand 25 12 Mg
Solution
Isotopesareatomswiththesameatomicnumberbutdifferentmassnumber.Hereonly(b) and(d)areisotopes.
1.4RelativeAtomicMass
Therelativemassofanatomiscalledatomicmass(oldertextbookscallit“atomicweight”) andischaracteristicofeachelement.Themassofanindividualatomisdifficulttomeasure,but therelativemassesoftheatomsofdifferentelementscanbemeasured,andthisdeterminesthe atomicmass.
Themassesofindividualatomsandmoleculesareexceedinglysmallandcannotbeconvenientlyexpressedingramsorkilograms.Forexample,oneatomofCahasamassof 6 64 × 10 23 g.Forthisreason,scientistsinsteadusearelativeatomicmassscale.Scientistshave chosenthecarbon-12isotopeasareference,anditsmassisdefinedasexactlytwelveatomicmass units(amu).Thereforeoneatomicmassunitisequalto 1 12 ofthemassofthecarbon-12atom. Oneamuhasbeendeterminedexperimentallytobe1.66 × 10 24 g.
Therelativeatomicmassofanelementisdefinedasthemassofanatomofthatelement comparedwith 1 12 ofthemassofthecarbon-12isotope.
Theatomicmassesofelementsgivenintheperiodictablearenotthesameasmassnumber.In nature,mostelementsoccurasamixtureofisotopes.Therefore,theatomicmassofanelement isanaveragemassbasedontheabundanceoftheisotopes.
1.4.1Calculatingatomicmasses
Theinformationneededtocalculatetheatomicmassesofelementsincludes:thenumberof isotopesfortheelement,therelativemassofeachisotopeonthecarbon-12scale,andthepercent abundanceofeachisotope.
Theatomicmassofagivenelementisthenobtainedasthesumoftheproductoftheexactmass ofeachisotopeanditspercentabundance.Forexample,naturallyoccurringcarbonconsistsof
amixtureof98.89%carbon-12(12 6 C)withamassof12.00000amu,and1.11%carbon-13(13 6 C) withamassof13.00335amu.Theatomicmassisobtainedasfollows: Atomicmass = (12 00000amu) 98 89
+ (13 00335amu)
Aninstrumentcalledthemassspectrometermeasurestheexactmassofeachisotopeandits relativeabundance.
Example1.4
Calculatetheaverageatomicmassoflithium,whichisamixtureof7.5% 6 Liand92.5% 7 Li. Theexactmassesoftheseisotopesare6.01amuand7.02amu.
Solution
Multiplyingtheabundanceofeachisotopebyitsatomicmassandthenaddingtheseproducts givestheaverageatomicmass. AverageatomicmassofLi = (6 01amu)
+ (7 02amu)
Example1.5
Boron,B,withanatomicmassof10.81,iscomposedoftwoisotopes, 10 Band 11 B,weighing 10.01294and11.00931amu,respectively.Whatisthefractionandpercentageofeachisotope inthemixture?
Solution
Lettheabundanceof 10 BbeXandthatof 11 Bbe1 Xsincethereareonlytwoisotopesof boron.Therefore,
Atomicmass = 10 81 = (X) (10 01294) + (1 X) (11 00931)
NowsolveforX: 10 81 = 10 01294X + 11 0093 11 0093X 10.0129X 11.0093X = 10.81 11.0093 0.9964X =−0.1993
X = 0 20or20%and1 X = 0 80or80%
Thefractionand%of 10 Bis0.20or20%.Also,thefractionof 11 Bis0.80or80%.
1.5Problems
1.Howmanyprotons,neutrons,andelectronsareineachofthefollowing?
(a) 197 79 Au (b) 10 5 B (c) 40 20 Ca (d) 163 66 Dy
2.Howmanyprotons,neutrons,andelectronsareineachofthefollowing?
(a) 84 36 Kr (b) 24 12 Mg (c) 69 31 Ga (d) 75 33 As
3.Findthenumberofprotons,neutrons,andelectronsinthefollowingions:
(a) 59 27 Co2+ (b) 24 12 Mg2+ (c) 69 31 Ga3+ (d) 118 50 Sn2+
4.Identifythefollowingatomsorions.
(a)Ahalogen(anelementingroupVIIoftheperiodictable)anionwiththirty-six electronsandthirty-fiveprotons.
(b)Analkalimetal(anelementingroupIoftheperiodictable)cationwithfifty-five protonsandfifty-fourelectrons.
(c)Atransitionmetalcationwithtwenty-fiveprotonsandtwenty-threeelectrons.(Note: TransitionelementsarethoseelementsembeddedbetweengroupsIIandIIIinthe periodictable).
5.Completethefollowingtable. Symbol 40 20 Ca2+ 79 34 Se2 137 56 Ba2+ Massnumber23815 Protons15 Neutrons161468 Electrons88 Netcharge 3 3
6.Withtheaidofaperiodictable,identifythefollowingelements: (a) 56 26 X; (b) 131 53 X; (c) 202 80 X; (d) 19 9 X
7.Fillintheblanksinthefollowingtable:
ParticleAtomicMassNumberofNetchargeSymbol numbernumberprotonsneutronselectrons
A3580 1 B13143 C3115P3 D242824 E35170 F541310 G2048180 H40514Zr4+
8.Findthenumberofprotons,neutrons,andelectronsinthefollowingions: (a) 32 16 S2 (b) 80 35 Br (c) 128 52 Te2 (d) 14 7 N3
9.Naturallyoccurringchlorinehastwoisotopes,whichoccurinthefollowingabundance: 75.76% 35 17 Cl,withanisotopicmassof34.9689amu,and24.24% 37 17 Cl,withaisotopic mass36.9659amu.Calculatetheatomicmassofchlorine.
10.Boronhastwonaturallyoccurringisotopes:80%of 11 5 B,and20%of 10 5 B,whichhasan isotopicmassof10.02amu.Iftheatomicmassofboronis10.81,whatistheisotopic massof 11 5 B?
11.Naturallyoccurringoxygengasconsistofthreeisotopes.Usetheinformationinthetable tocalculatetheatomicmassofoxygengas.
IsotopeExactmassAbundance
12.Naturallyoccurringgallium(Ga)existsintwoisotopicforms, 69 Gaand 71 Ga.Theatomic massofGais69.72.Whatisthepercentageabundanceofeachisotope?(Theexact isotopicmassesof 69 Gaand 71 Gaare68.9259and70.9249,respectively).
