課件-結(jié)構(gòu)化學(xué)chapter

Chapter9IonicCompoundsLatticeyMn+(g)yMn+(g)+nXy-(g)MyXnHThelatticeenergyEThelatticeenergyElatticeistheenergyliberatedwhenonemoleoftheioniccompoundisformedat0Kfromisolatedgaseouscationsandanions-Sumofcoulombicinteractionsinasolidioniccanbecalculated(生成ormeasuredfromHf(生成TheTheenergyrequiredtobreakthesebondsforonemoleofanionicsolidunderstandardconditionsisthelatticeenergy.CalculatinglatticeenergiesColumbicionpairIon-ionattractionforanisolatedpair

ze2

Arepulsionenergyoftheelectronclouds0 400permittivityofz±m(xù)agnitudeofchargeoneachtypeofioninelectroniccharge theinternuclear

RBrmB,m:Ion-ionattractioninegforNaCleachNa+issurrounded-6Cl-ionatdistancer(face-12Na+ionsat2r(edge -8Cl-ionat3r(corner-6Na+ionsat4randon(nextAllofthesecolumbicinteractionscanbe(Na)ZZ2 [6 8234ZZeAStructure-A MadelungconstantforNaCl

ze2ccThenumericalvaluesofMadelungconstantsAforavarietyofdifferentstructuresarelistedinthefollowingtable.CNisthecoordinationnumber(cation,anion)andnisthetotalnumberofionsintheempiricalformulae.g.influorite(CaF2)thereisonecationandtwoanionsson=1+2=3.AA/ZincNoticethatthevalueofAisfairlyconstantforeachgivenstoichiometrythatthevalueofA/nisverysimilarregardlessofthetypeof(Na)

Z

[6

8

4Z

EEC

Z4

ANA

323ZZ

122Z234 122Z23440

ZZe2 2Z 0r400r

(

)r

4r

ANA

m1eZZe2B AeA e

2

Er

uZZe4

(11m(Cl)N

ZZe2AA

ZZ

0LatticeEc A[(Na)(Cl)] ANA Elattice=-753(-7.81Therepulsion Born-HaberLatticeenergiesaredeterminedexperimentallyusingaBorn-HabercyclesuchasthisoneforNaCl.Na(s)Na(g)?Cl2(g)Cl(g) LatticeEnergy,-410.9=108.4+495.0+1/2(239.2)+(-348.3)+Uo=-785.6ThelatticeenergyofNaClis-788LargerElatticeusuallymeanscompoundismoresmallcationandaniongiveslargerhigherchargesgivelargerLatticeenergiesforsomeionicLatticeenergyLatticeenergyElatticevaluebythemselvesarenotveryComparisonsofElatticefordifferentcompoundsThestructureofsometypicalionicABAB2

ManyionicsolidsfallintooneofafewtypesofionicTypicallynamedafterthefirstormostcommonionicsolidtohavethatstructureUsuallycorrespondtofccorhcpanionswithcationsfoundinTdorOhholesAnswerthefollowingCrystalSystem(+BravaisThepackingstyleofanionsThepositionofcationsTheC.N.ofanionandcationAtomnumberinoneunitStructuralformulaAtomicoctahedraloctahedraltetrahedralholeholesizeis0.414RCN:6holesizeis0.225RCN:4HCP octahedralholesinHCP tetrahedralholesinHCPa2

2+8/4=WithinaWithinaunitcell:22octahedralNspheresresultinNoctahedralWithinaunitcell:2 tetrahedralNspheresresultin2NtetrahedralRocksaltFCCarrayofanionswithcationsinalloctahedralholes(orviceversa)CN+CN+:CN-=Basis:NaClBasisnumber:LatticeType:Na:Cl:SrSe,SrSe,CaS,KI, MgO,FeO,LiF,KCl,CaO,NiO,KCl,KBr,SrS,RbI,S (1/2,0,1/2)ZnS (1/2,0,1/2)Zn(1/4,1/4,1/4)(3/4,1/4,3/4)閃鋅 FCClatticeofS2-OnehalfofTdholeisOneoftwocommonpolymorphsofogue:ogue:SiC,BeS,ZnSeCuF,CuBr,CuI;AgI;ZnTe;CdS,CdSe,CdTe;HgS,HgSe,HgTeCN+:CN-=4:Basis:Zn2+,S2-Basisnumber:4LatticeType:WurtziteZnS纖鋅 2ndcommonpolymorphofS2-makeuptheHCPcZn2+occupyonehalfoftheTdcLookforABABCN+:CN-=4:

aSAtomsperunit:2Zn2+and2LatticeType: C P6 S(0,0,0)(1/3,S(0,0,0)(1/3,2/3,Zn(0,0,5/8)(1/3,2/3,

ogue:CdS,HgS,HgSe, ZnO,ZnO,AlN,GaN,InN,CuF,CuBr,CuI,ZnSe,CdS,NiAs(NickelineorniccoliteAs2-makesuptheHCPNi2+occupyalltheoctahedralholes(LookforAbAcAbAc...closestacking)

ccbaCN+:CN-=6:Atomsperunit:CN+:CN-=6:Atomsperunit:2Ni2+,LatticeType:HexagonalD4

Ni(0,0,0)Ni(0,0,0)(0,0,As(2/3,1/3,1/4)(1/3,2/3,cbaAs-ogue:FeS,NiS,CoTe,PtSn,CoSNonclosepackedNonclosepacked1:1ratioofcationsandSimplecubiclatticeofanionswithacubicholefilledbyacationCN+:CN-=CN+:CN-=Basis:Basisnumber:LatticeType:Simple?Cs:Cl:verysimilarsizeandAnologue:RbCl,RbBr,RbI,CsBr

Fluorite(CaF2)熒石結(jié) (1/2,0,1/2)F(1/4,1/4,1/4)(3/4,3/4,1/4)(3/4,1/4,3/4)(3/4,3/4,3/4)(1/4,1/4,3/4) (1/2,0,1/2)F(1/4,1/4,1/4)(3/4,3/4,1/4)(3/4,1/4,3/4)(3/4,3/4,3/4)(1/4,1/4,3/4)(1/4,3/4,1/4)anions(eg.Ca2+makeup F-occupyallthetetrahedralCN+CN+: =8:Basis:BasisnumberLatticeType:FFluorite(CaF2)熒石Fluorite(CaF2)istypicalofdivalentcationswithanions(eg.Ca2+makeup F-occupyallthetetrahedral

F-:136Ca2+:99

????F-makeupthesimplecubicCa2+occupyonehalfofcubics.pNo.225Fm-F-F-Ca2+:FFluorite(CaF2)熒石Fluorite(CaF2)istypicalofdivalentcationswithanions(eg.Ca2+makeup F-occupyallthetetrahedral

F-:136Ca2+:99

F-F-Ca2+:ogue:BaF2,PbF2,SrF2,HgF2,ThO2,CaF2,UO2,CeO2,PrO2,CdF2Fluorite

Antifluorite(Rb2O,Li2O,反熒石結(jié)構(gòu)（反Ca2F結(jié)構(gòu))Antifluoriteistheopposite.MonovalentcationsinTdholeswithdivalentanionsformingtheFCClattice(oxidesand

MX2stoichiometryforexampleCN+: =6:Atomspreunit:2Ti4+,CN+: =6:Atomspreunit:2Ti4+,LatticeType:TetragonalD4hpointspace(cP)D14P42212D mn

uu uca aFeO2MnF2、NiF2TeO2,MnF2PbO2FeF2、CoF2、ZnF2NiF2MgF2SnO2、OsO2、IrO2、RuO2Ti(0,0,0)O(u,u,0)(u (1/2+u,1/2-u,1/2)(1/2-u,ForTiO2, RockAll66NaCl,FeO,LiF,CesiumSimple88Zinc44ZnS, 44Nickelall66FeS,NiS,ABFCC84holes(O2-1/2AB1/263TiO2,IonicIonicradiiandbondIonicradiicannotbe“measured”-estimatedfromtrendsinknownstructuresdFromX-raydiffractionwecanmeasurethedistancebetweentwoions,ddd=r++O2- O2-WasastjernaWasastjerna(1925)interionic r+,2.Pauling’sHowdidPaulingdetermineionicHeassumedthespacingoftheionsisHefoundawaytodividetheHowdidPaulingdividether=Cn/(Z-)=r=Cn/(Z-)=Cn:constantdeterminedbynr+/r-=Z-*/Z+*noblegas PaulingPaulingr=Cn/(Z-)=Cn:constantdeterminedbynr+/r-=Z-*/Z+*135O135O2-140r1=6.15/Z*(forNetype,r+1,r-For rz=r1(z)-2/(m- (m=7forNeForO2-,Z*=8-(20.85+70.35)=8-4.15=r1(z=1)=6.15/3.85=1.76r(O2-)=1.76*2-2/6=1.76*0.794=1.40IonicFF-135O2-1403.3.Effectiveioniccoordinationnumberoftheionsisimportantindeterminationofionic 等歸納整理實(shí)驗(yàn)測(cè)定的上千個(gè)氧化物和氟化 Coord.LengthC-3Si-4Si-6Ge-4Ge-6SnIV-6PbIV-6PbII-6IonradiiforgivenelementincreasewithIonradiiforgivenelementdecreasewithincreasingoxidationstate/positivechargeRadiiincreasegoingdownaAnionsoftenbiggerthan Thetrendofvariationofionic IneachofthegroupsIA,IIA,IIIA-VIIAintheperiodictable,theionicradiusoftheelementsinthesamegroupincreaseswiththeatomicnumber.(theadditionofelectrons

Withinthesameperiodoftheperiodictable,theionicradiusoftheisoelectroniccationsdecreasesasthepositivechargeincreases.Na+Au+

Mg2+Hg2+

Al3+Tl3+

Pb4+

TheionicradiiofthevariousvalencestatesofaparticularionvaryproportionallytonumberofelectronsCr2+ Cr3+ Cr4+ Cr6+

Foranisoelectronicpairofanions,theradiusincreaseslightlyasthenegativechargeF-Cl-Br-

O2-S2-Se2-

負(fù)離子半徑:1.30~2.50,正離子半徑:Forcationsindiagonalposition(top-leftto負(fù)離子半徑:1.30~2.50,正離子半徑: (Li+0.60,Mg2+0.65;Na+0.95,Ca2+0.99;Sc3+0.81,Zr4+“Lanthanidecontraction”effect:Thesix-coordinatetrivalentionicradiiofthelanthanidesdecreaseswithincreasingatomicnumberfrom1.032ofLa3+to0.861ofLu3+ How HowtopredictionThreeelementstodetermineionChemicalMagnitudeoftheelectricalchargeoneachion.Chargebalancedictateschemicalformula(Ca2+andF-formCaF2)W+/W- -=n-(正離子價(jià)數(shù)/負(fù)離子價(jià)數(shù)=正離子配位數(shù)/負(fù)離子配位數(shù)radiusratio(r+/r-RelativesizesofthecationsandIonicTransitionsformionicbondtocovalentChemicalStableStableioncrystal Anionssurroundingacationareallincontactwiththatcation.Cationswants umpossiblenumberofanionnearestneighborsandvice-versaThegreatertheratioofcation:anion(r+/r-)sized,thehigherthecoordinationnumberofthecationcanandSHOULDbe unitcellcellsidea

unitfacediagonal

1/8unitbodydiagonalforaCsCl,theanionsjusttouchalongtheedgeoftheunitforNaCl,theanionstouchalongthefaceforZnS,theanionstouchalongthebodyCsClcellside

NaClfacediagonal

ZnSbodydiagonal 3rr 321

r

12

rr 4r2

4r r2

2r a r2223r 223

2rr233

2rr2331021r3122

0.155- 0.414-

findtheratio(r+/r-prediction0.155-0.225-0.414-

Comp. 333

0.732-Onlyabout2/3correct.StructurestypeofioncrystalsdonotdependonradiusratioNotesabouttheradiusratioThisworksbestforhighlyionicCoordinationnumbersareoftensignificantlylowerforcompoundsinwhichionsarehighlypolarizable.(e.g.,copper(I)andzincIonicCovalentCharacterinPredominantlyIonicIermediateIdealizedionpair mutuallypolarizedWithnopolarizationionpairThepolarizabilityofThepolarizabilityofinduced=

polarizationtoformcovalentthethepolarizabilityofionsResultsofbonddistance esshort,bondtypechangesfromionicto2)2)coordinationnumberis(anions’surrounding,ofcovalent 6:6ForrdAg-XrAg++rX-rAg-+rX+- NaClZnSResultsofMetingpointandboilingCaCl2(782NaBr(747BeCl2(405MgBr2(700AlBr3(97.5LiF(845LiCl(605LiBr(550 LiI(449CaCl2(782HgCl2(276Thesolubilityof silverfluoridesilverchloridesilverbromidesilveriodide

2x10-5x10-8x10-(r+/r-(r+/r-Structuretypechangesfrom2D1Disolated三維層型鏈型島型干干冰晶體結(jié) Structuresofpoly-ionicABO3,AB2O4,ABO4TwotypicalionicPerovskiteABX3（鈣鈦礦結(jié)構(gòu)）:CaTiO3BaTiO3ImportantareaclassofmaterialsfortemperaturesuperconductorsMultiplesitesandcoordinationsleadtomanypotentialdistortionsandnon-stoichiometricsolidsPerovskiteanInorganicABX3-threecompositionalvariables,A,BandCaTiO3-BaTiO3-Pb(Mg1/3Nb2/3)O3-relaxor(Y1/3Ba2/3)CuO3-x-

NaxWO3-mixedSrCeO3-H-protonicReCoO3-x-mixed(Li0.5-3xLa0.5+x)TiO3-lithiumLaMnO3-x-GiantPerovskiteABO3（鈣鈦礦結(jié)構(gòu)AandBABc(A

(BA:(0A:(00B:(1/21/2X(1/21/20)(01/21/2)(1/20A:(1/21/2B:(00X:(1/200)(01/20)(00 Bin1/4ofoctahedralNottraditionalclosepacking-mixed

InInSrTiO3,a=3.91Ti-O=a/2=1.955Sr-O=a2/2=2.765BB ABFormula:Formula:Bravaislattice:simplecubic(Oh)Basis:5ions(1Sr2+,1Ti4+,3O2-)Atomsperunit

AAOAAOTiTi4+:atthebodycenterSr2+:atcornersO2-:atfaceSr2++O2-:C.N.Sr:Ti:O=12:6: SrTiO3,KNbO3,LaMnO3,CaTiO3,BaTiO3,OInSrTiO3,Ti-O~OatypicalbondlengthforTi-O;a=b=3.9945?c=4.0335a=b=3.9945?c=4.0335InBaTiO3,Ti-Oisstretched,>2.0COToolongforaCOonesquarepyramidalThiscreatesanetdipolemomentDisplacementby5-10%Ti-ObondRandomdipoleorientationsAligneddipoleorientations

Underanappliedelectricfield,dipoleorientationscanbereversed,i.e.thestructureispolarisableDipolestendtobe‘frozenin’atroomtemperature;asincreasetemperature,thermalvibrationsincreasethepolarisabilityReO3and(B(BBXcab

La4+O2-ReO3,WOReO3,WO3:exceptLa2CuO4:Atype+2BwithoutBasis:2(B

YBa2Cu3O7Oxygen

23O7Tc93K時(shí)，其電阻率OanionsformFCC

AB2O4 (A2+, Mg2+(A)in (B)in1/2octahedralOanionsformFCC

AB2O4 (A2+, Mg2+(A)in (B)in1/2octahedral SpinelMgAl2O4 OanionsformFCCMg2+(A)in1/8tetrahedral (B)in1/2octahedral

AB2O4 (A2+,

Oc? CoordinationCdCr2S4,CoMn2O4,anti-spinel（反尖晶石結(jié)構(gòu)）magnetitemagnetite(Fe3O4)=(Fe3+(Fe3+,Fe2+)O4=BCoordination46Coordination464Fe3+cations Siteaccountancyinunit32Siteaccountancyinunit326483288Anti-spinel SchematicdiagramshowingthespinAnti-spinel ?ogy:CoFe2O4,?ogy:CoFe2O4,MoFe2O4,FeIn2S4,FeFe2O4cb a PaulingruleforionicRuleforpolyhedral:anionsandcationsformStackingsequenceofanionsinterstitialsitesoccupiedbycationsCoordinationnumbersdependuponradiusratior+:r-Bondlength=r++r-NaClRockZnS(ZincRuleforZ

isi iZs

靜電鍵強(qiáng):coordinationnumberof 配位數(shù)(C.N.)Thechargeofeachanionisexactlyofnearlyequaltothesumofthestrengthsoftheelectrostaticbondstoitfromtheadjacentcations每一負(fù)離子的電價(jià)=從鄰近正離子至該離子Example Si2O76-:s(Si4+)= Z-(O)=1+1(train,SilicaTetrahedronSiO4SiO44-canbeSilicaTetrahedronSiO4 isi ZiisZExample

SS2O72-:s(S6+)=6/4=Z-(O)ItisadiscreteionicgroupwhereastheCO32-,NO3-,PO43-,Thesilicatetetrahedronandformationofsheetsandnetworksofsilicaten.橄欖石,石 isi ZiisZExample Z-(Cl)=6*1/6Example BaTiO3:Z-(O)=2*2/3+4*1/6=C.N.Ba:Ti:O=12:6:

Theruleofvertex-,edge-andface-Thepresenceofsharededgesandespeciallyofsharedfacesinacoordinatedstructuredecreasesitsstability:thiseffectislargefo