WPC * ԥl3(U%ʯ!ȇ/{u@{R$TgOu͆3y㝨+4Dz5znJ؀/˅q,4g%'n+iZAv1#ˠ1%rAJ֙k.L4bl1Ĉatɉ|,IFA;2eQi`ds<=88`@=%Guv9,׿g6xG wK&Y7{kˊH%F\ 0d 0+ 0 0 0 0 0 0  0  0v 0^ 0C 0( 0  0 0 0 0 0b 0I 0- 0 0 0 0 0 0j 0 <E U@:! 0<! 0/! 0&# 1U$ 7 %%U ,1% 1U]% 7 % 1W% 7 &!& 01&#&UN( %)M)()N:) 1u<) 72)^ )w)4)* m *\  `&Times New Roman' CHAPTER 4 susie0Giordano .   2P+M 0_level1  , 8.4 <DL!823  ..  5+ 4 <DL!5  2M+M 0_level2  X 5+4 44 <DL!523  ..  5+ 4 <DL!5  2M+M 0_level3   5+` ` ` <DL!523  ..  5+ 4 <DL!5  2J+M 0_level4   2( <DL!223  ..  5+ 4 <DL!5  2J+M 0_level5   2( <DL!223  ..  5+ 4 <DL!5  2G+M 0_level6   /% <DL!/23  ..  5+ 4 <DL!5  2G+M 0_level7  4 /% <DL!/23  ..  5+ 4 <DL!5  2D+M 0_level8  ` ,"< <<DL!,23  ..  5+ 4 <DL!5  2D+M 0_level9   ,"h hhDL!,23  ..  5+ 4 <DL!5  2PM 0_levsl1  , 8.4 <DL!823  Ԁ  5+ 4 <DL!5  2MM 0_levsl2  X 5+4 44 <DL!523  Ԁ  5+ 4 <DL!5  2MM 0_levsl3   5+` ` ` <DL!523  Ԁ  5+ 4 <DL!5  2JM 0_levsl4   2( <DL!223  Ԁ  5+ 4 <DL!5  2JM 0_levsl5   2( <DL!223  Ԁ  5+ 4 <DL!5  2GM 0_levsl6   /% <DL!/23  Ԁ  5+ 4 <DL!5  2GM 0_levsl7  4 /% <DL!/23  Ԁ  5+ 4 <DL!5  2DM 0_levsl8  ` ,"< <<DL!,23  Ԁ  5+ 4 <DL!5  2DM 0_levsl9   ,"h hhDL!,23  Ԁ  5+ 4 <DL!5  2PM 0_levnl1  , 8.4 <DL!823   5+ 4 <DL!5  2MM 0_levnl2  X 5+4 44 <DL!523   5+ 4 <DL!5  2MM 0_levnl3   5+` ` ` <DL!523   5+ 4 <DL!5  2JM 0_levnl4   2( <DL!223   5+ 4 <DL!5  2JM 0_levnl5   2( <DL!223   5+ 4 <DL!5  2GM 0_levnl6   /% <DL!/23   5+ 4 <DL!5  2GM 0_levnl7  4 /% <DL!/23   5+ 4 <DL!5  2DM 0_levnl8  ` ,"< <<DL!,23   5+ 4 <DL!5  2DM 0_levnl9   ,"h hhDL!,23   5+ 4 <DL!5  6 x4Heading 1 CE O* `"Comic Sans MSO   XXXS\  `&Times New RomanS CE * `"Comic Sans MS<:Default Para6|} 4Body Text   O* `"Comic Sans MSO     XXXS\  `&Times New RomanS < :Body Text In  O* `"Comic Sans MSO  5+  <DL!5  5+ 4 <DL!5XXXS\  `&Times New RomanS   359=AEIMQ1 - o o# (\ Y`Symbol 359=AEIMQ2 o o o&  359?CGKOS3 1. o o( #|x(Y$..      CEUS.,-XXX-XXXX-XLexmark 3200 Series ColorFinePX,,,,PX0(9 Z6Times New Roman Regular-X3#37=CIQYag1.a.i.(1)(a)(i)1)a)2i)<N- TI-d@ӠU +Y!..      CEUS.,-XXX-XXXX-X  _       ! XX       !  CHAPTER4.2:THENATUREOFTHECHEMICAL  BOND!h݌ `s Ќ  XX XXXX   OXX9O # (032/ /""  ,B.4 <DL!XB  X,E(4 4 <DL!4X!E%{ 9@2 3   4   9 %{ThemathematicalequationdevelopedbySchrodinger ]p describesastandingwaveforanelectronandisusedto   constructaparticularvolumeofspace(orbital),onefor   eachquantumstateoftheelectron,inwhichtheprobability , ?  offindinganelectronishigh.@=݌ q  Ќ X! X44X!!   ""  ,B.4 <DL!XB  X,E(4 4 <DL!4X!E%{ 9m2 3   4   9 %{Thevariousorbitalsareusuallyvisualizedaselectronclouds   andhavecharacteristicshapesandorientations:eg.1s,2s8mj݌   Ќ X! X44X!!   ""  ,B.4 <DL!XB  X,E(4 4 <DL!4X!E%{ 92 3   4   9 %{Anatomhasonlyonenucleustoconsider,butamoleculehas @S  twoormorenucleiandmoreelectronstotakeintoaccount. ݌   Ќ X! X44X!!   ""  ,B.4 <DL!XB  X,E(4 4 <DL!4X!E%{ 9= 2 3   4   9 %{Inordertodealwiththecomplexityofseveralatomsina   molecule,somesimplificationsarerequired.= : ݌ " Ќ X! X44X!!   ""  ,B.4 <DL!XB  X,E(4 4 <DL!4X!E%{ 9 2 3   4   9 %{Oneapproachistostartwiththeindividualatoms,with Tg theirorbitals,andthenbuildthemoleculeusingatomic  orbitalstoformcovalentbonds. ݌  Ќ X! X44X!!   ""  ,B.4 <DL!XB  X,E(4 4 <DL!4X!E%{ 9$2 3   4   9 %{Thisapproachiscalledthe ValenceBondTheory developed #6 byLinusPauling.$!݌ h{ Ќ X! X44X!!   ValenceBondTheory: !  ""  X?+4 44 <DL!X?  X?% <DL!444X!?O92-3     9OAcovalentbondisformedwhentwoorbitalsoverlap %" (sharethesamespace)toproduceanewcombined &# orbitalcontainingtwoelectronsofoppositespin.݌ (-% Ќ ! X  X!!   ""  X?+4 44 <DL!X?  X?% <DL!444X!?O9#2-3     9OThisarrangementresultsinadecreaseintheenergy _)r& oftheatomsformingthebonds.#݌ *' Ќ ! X  X!!    .-A*! " 9999 ?+  <DL!X?  "n  ݀Eg.Theformationofasinglecovalentbondinahydrogen  moleculebytheoverlapoftwo1sorbitalsofindividual 2E hydrogenatoms."n"݌ w Ќ ' X X!'9999    ?+  <DL!X?     F Y         (   Zm         )<   n        & (00# / /""  ,K.4 <DL! X!K  X,E(4 4 <DL!4X!E%{ 92 3   4   9 %{Noticethatthenewcombinedorbitalcontainsapairof =P electronsofoppositespin.݌  Ќ X* X!44X!*   ""  ,K.4 <DL! X!K  X,E(4 4 <DL!4X!E%{ 92 3   4   9 %{Anytwohalffilledorbitalscanoverlapinthesameway.݌  Ќ X* X!44X!*   H+  <DL! X!H    Qd Eg.Theorbitaldiagramforthehydrogenfluoridemolecule.      3  e!x  "  #!  4%G"  y&#  '$  )&  H*['  +(    H+ 4 <DL! X!H ,)! Eg;Theorbitaldiagramforthewatermolecule.  ReadoverSummary:ValenceBondTheory 4%G" ЀPage232 y&# DoQuestionspage232233#1,2,3,4,5(a),(b),(c) )&  ,)!  HYBRIDORBITALS:    ( (00& / /""  ,E.4 <DL!X!E  X,E(4 4 <DL!4X!E%{ 9u$2 3   4   9 %{Lewisbondingtheorywasunabletoexplain:u$u%݌ w Ќ X$ X!44X!$   ,E.4 <DL!X!E""  X,H+4 44 <DL!4X!H  X?% <DL!444X!?&2  1  .3     thefourequalbondsrepresentedbyfourpairsof  electronsinacarboncompound&'݌ F Y Ќ ,*4X!  X!*   ""  X,H+4 44 <DL!4X!H  X?% <DL!444X!?(2  2  .3     theexistenceofdoubleandtriplebonds()݌   Ќ ,*4X!  X!*   ,H+ 4 <DL!4X!H""  ,E.4 <DL!X!E  X,E(4 4 <DL!4X!E%{ 9$+2 3   4   9 %{Paulingandotherswereabletoexplaintheevidencethat  (  carbonformsfourbondsofequallengthdistributedina Zm  tetrahedron.$+$,݌   Ќ X$ X!44X!$   ""  ,E.4 <DL!X!E  X,E(4 4 <DL!4X!E%{ 9-2 3   4   9 %{Theyfirstcreatedtheideaofelectronpromotionfromans   toanemptyporbital(fig.6(a),page233)-.݌ )<  Ќ X$ X!44X!$   ""  ,E.4 <DL!X!E  X,E(4 4 <DL!4X!E%{ 902 3   4   9 %{However,experimentalevidenceindicatedthattheelectron n  orbitalswereequivalentinshapeandenergythereisnot  onethatismore sthantheothers.01݌   Ќ X$ X!44X!$   ""  ,E.4 <DL!X!E  X,E(4 4 <DL!4X!E%{ 922 3   4   9 %{Asaresult,thefourbondsforcarboninmoleculessuchas =P methaneareexplainedby hybridization tofouridentical  hybridsp3atomicorbitals.23݌  Ќ X$ X!44X!$   ""  ,E.4 <DL!X!E  X,E(4 4 <DL!4X!E%{ 9O52 3   4   9 %{Thetwo2selectronsandthetwo2pelectronsformfour   sp3 hybridorbitals withonebondingelectronineach.O5O6݌ Qd Ќ X$ X!44X!$   ""  ,E.4 <DL!X!E  X,E(4 4 <DL!4X!E%{ 972 3   4   9 %{Thisexplainsthebondingcapacityoffourforcarbon(fig.6  (b),(c),page233).78݌  Ќ X$ X!44X!$   ""  ,E.4 <DL!X!E  X,E(4 4 <DL!4X!E%{ 9:2 3   4   9 %{Theseorbitalsarehybridizedonlywhenbondingoccursto  3 formamolecule:theydonotexistinanisolatedatom.:;݌ e!x Ќ X$ X!44X!$   ""  ,E.4 <DL!X!E  X,E(4 4 <DL!4X!E%{ 9d<2 3   4   9 %{ThePaulingtheoryisthatsp3hybridorbitalsare " spontaneouslyformedastheseorbitalsoverlapwith,say,1s #! orbitalsofthehydrogenatom(fig.7,page233).d<d=݌ 4%G" Ќ X$ X!44X!$   " "  ,E.4 <DL!X!E  X,E(4 4 <DL!4X!E%{ 9?2 3   4   9 %{Thisresultsinapairofelectronsineachorbitalanda y&# noblegaslikestructurearoundeachatom.?@݌ '$ Ќ X$ X!44X!$    ,)!  GOFIGURE?!!   CECE.,9999    &  A  Howdoyouexplainthecovalentbondingintheempirically w determinedformulasforboronandberyllium,eg.,BF3(g)and  BeH2(s)?A,B BԌ  Ќ9999CE.,CE.,  'w BCECE.,9999    &  C  ObserveandDrawTable1page234.FormsofHybridizationC8D DԌ   Ќ9999CE.,CE.,  ' ,DCECE.,9999    &  DE  Do:PracticeProblemspage235DEE EԌ  (  Ќ9999CE.,CE.,  ݀Questions#8,9,10,11,13' E Zm   DOUBLEANDTRIPLECOVALENTBONDS: )<    & (0 0 ( / /""  ,E.4 <DL!X!E  X,E(4 4 <DL!4X!E%{ 9G2 3   4   9 %{Howcanmanyformulasbeexplainedtheoretically?GH݌  Ќ X$ X!44X!$    # (00& ""  XB+4 44 <DL!X!B  X?% <DL!444X!?O9oJ2-3     9OLewissuggestedthatbetweenthecarbonatomsthere   mustbeasharingofone,two,andthreeelectronpairs =P inordertoobtainastableoctetaroundthecarbon  atoms(fig.8,page236).oJfK݌  Ќ $ X!  X!$   ""  XB+4 44 <DL!X!B  X?% <DL!444X!?O97M2-3     9OHowever,eventhoughtheLewisstructuresfollowthe   octetruleandthepairingofelectrons,theydonot Qd explainhowelectronsareshared.7M.N݌  Ќ $ X!  X!$   Howisitpossiblethatelectronsinwhatwewouldpredictas  3 beingsp3hybridorbitalscouldoverlapnotonce,buttwiceor e!x threetimeswithjustoneotheratom? " AccordingtotheValenceBondtheory,isthattwokindsof 4%G" orbitaloverlaparepossible. y&# ""  XB+4 44 <DL!X!B  X?% <DL!444X!?O9'Q2-3     9OEndtoendoverlapofsorbitals,porbitals,hybrid )& orbitals,orsomepairoftheseorbitals.'QR݌ H*[' Ќ $ X!  X!$   ""  XB+4 44 <DL!X!B  X?% <DL!444X!?O9lS2-3     9OԀIntheValenceBondstheory,thistypeofoverlap +(  producesa sigmabond(%{ 9s 9 %{) (fig.9,page236).lScT݌ ,)! Ќ $ X!  X!$   ""  XB+4 44 <DL!X!B  X?% <DL!444X!?O9U2-3     9OThinkofsigmabondsasthesinglecovalentbondsyou  drawinstructuraldiagrams.UV݌ 2E Ќ $ X!  X!$   ""  XB+4 44 <DL!X!B  X?% <DL!444X!?O93X2-3     9OWhentwoorbitalsoverlapsidebysidetoforma pi w bond(%{ 9p 9 %{). 3X*Y݌  Ќ $ X!  X!$   ""  XB+4 44 <DL!X!B  X?% <DL!444X!?O9Z2-3     9OPibondsarethesecondandthethirdlinesinthe  structuraldiagramsfordoubleandtriplecovalent F Y bonds.Z[݌   Ќ $ X!  X!$    ,)!  DOUBLEBONDS:    & (00# ""  ,E.4 <DL!X!E  X,E(4 4 <DL!4X!E%{ 9]2 3   4   9 %{Thecarbonatomisthemostcommoncentralatomin w moleculeswithdoubleandtriplecovalentbonds.]^݌  Ќ X$ X!44X!$   ""  ,E.4 <DL!X!E  X,E(4 4 <DL!4X!E%{ 94`2 3   4   9 %{Theorbitalsofacarbonatomcanbehybridizedtoform  foursp3hybridorbitals.4`4a݌ F Y Ќ X$ X!44X!$   ""  ,E.4 <DL!X!E  X,E(4 4 <DL!4X!E%{ 9~b2 3   4   9 %{Thenewideaisapartialhybridizationoftheavailable   orbitalsleavingoneortwoporbitalswithsingleunpaired   electrons.~b~c݌  (  Ќ X$ X!44X!$   ""  ,E.4 <DL!X!E  X,E(4 4 <DL!4X!E%{ 9e2 3   4   9 %{Thehalffilledorbitalsarebelievedtooverlapsidewaysto Zm  formapibondwhilehybridorbitalsareusedtoformsigma   bondsbetweentheatoms.ef݌   Ќ X$ X!44X!$   ""  ,E.4 <DL!X!E  X,E(4 4 <DL!4X!E%{ 9g2 3   4   9 %{Thepibondisaregionofelectrondensityappearingabove )<  andbelowthesigmabonddirectlyjoiningthetwoatoms.gh݌ n  Ќ X$ X!44X!$   ""  ,E.4 <DL!X!E  X,E(4 4 <DL!4X!E%{ 9j2 3   4   9 %{Apibondisacombinedorbitalcontainingapairofelectrons  ofoppositespin.jk݌   Ќ X$ X!44X!$   ""  ,E.4 <DL!X!E  X,E(4 4 <DL!4X!E%{ 9Fl2 3   4   9 %{Theadditionalsharedpairofelectronsinthepibond =P providesgreaterattractiontothetwoatoms(usually  carbon)nuclei,whichexplainswhythedoublecovalentbond  isshorterthanasinglebond.FlFm݌   Ќ X$ X!44X!$   ""  ,E.4 <DL!X!E  X,E(4 4 <DL!4X!E%{ 9*o2 3   4   9 %{Incarboncarbondoublebonds,onesigmabondandonepi Qd bondbondsthecarbons.*o*p݌  Ќ X$ X!44X!$   ,E.4 <DL!X!EObserveFigures12,13(a),(b),(c)onpg.237.  3 PracticeProblem:Page238 )& Ѐ#18,19,21,23(a),(b),(c),24 H*['  ,)!  TRIPLEBONDS:   / /""  ,,K.4 <DL!4X!K  ,E(` ` <DL!4X!E%{ 9r2 3   `   9 %{Anotherpartialhybridizationproducesanexplanationfor w atriplebond.rs݌  Ќ ,-4X!` ` X!-   ""  ,,K.4 <DL!4X!K  ,E(` ` <DL!4X!E%{ 99u2 3   `   9 %{Observefigures15,16(a),(b),(c)onpage239.9u?v݌  Ќ ,-4X!` ` X!-   ""  ,,K.4 <DL!4X!K  ,E(` ` <DL!4X!E%{ 9Xw2 3   `   9 %{Incarboncarbontriplebonds,onesigmabondandtwopi F Y bondsbondthecarbons.Xw^x݌   Ќ ,-4X!` ` X!-   ,H+ 4 <DL!4X!HPracticeProblem:Page239   Ѐ#25,26(a),27,29(a),(b),(c),   ReviewSummary:ValenceBondTheory,Page240241   Read:CaseStudy,Page241  Ѐ TheStrangeCaseofBenzene   ̀HandinforAssignmentmark.  XX9XXXX