intermolecular forces of attraction - cobequid educational ：分子間的吸引力——cobequid教育

INTERMOLECULARFORCESOFATTRACTIONMETALLICBONDINGWHATISAMETALLICBONDMETALLICBONDINGINSODIUMMETALSTENDTOHAVEHIGHMELTINGPOINTSANDBOILINGPOINTSSUGGESTINGSTRONGBONDSBETWEENTHEATOMSEVENAMETALLIKESODIUMMELTINGPOINT978CMELTSATACONSIDERABLYHIGHERTEMPERATURETHANTHEELEMENTNEONWHICHPRECEDESITINTHEPERIODICTABLESODIUMHASTHEELECTRONICSTRUCTURE1S22S22P63S1WHENSODIUMATOMSCOMETOGETHER,THEELECTRONINTHE3SATOMICORBITALOFONESODIUMATOMSHARESSPACEWITHTHECORRESPONDINGELECTRONONANEIGHBOURINGATOMTOFORMAMOLECULARORBITALINMUCHTHESAMESORTOFWAYTHATACOVALENTBONDISFORMEDTHEDIFFERENCE,HOWEVER,ISTHATEACHSODIUMATOMISBEINGTOUCHEDBYEIGHTOTHERSODIUMATOMSANDTHESHARINGOCCURSBETWEENTHECENTRALATOMANDTHE3SORBITALSONALLOFTHEEIGHTOTHERATOMSANDEACHOFTHESEEIGHTISINTURNBEINGTOUCHEDBYEIGHTSODIUMATOMS,WHICHINTURNARETOUCHEDBYEIGHTATOMSANDSOONANDSOON,UNTILYOUHAVETAKENINALLTHEATOMSINTHATLUMPOFSODIUMALLOFTHE3SORBITALSONALLOFTHEATOMSOVERLAPTOGIVEAVASTNUMBEROFMOLECULARORBITALSWHICHEXTENDOVERTHEWHOLEPIECEOFMETALTHEREHAVETOBEHUGENUMBERSOFMOLECULARORBITALS,OFCOURSE,BECAUSEANYORBITALCANONLYHOLDTWOELECTRONSTHEELECTRONSCANMOVEFREELYWITHINTHESEMOLECULARORBITALS,ANDSOEACHELECTRONBECOMESDETACHEDFROMITSPARENTATOMTHEELECTRONSARESAIDTOBEDELOCALIZEDTHEMETALISHELDTOGETHERBYTHESTRONGFORCESOFATTRACTIONBETWEENTHEPOSITIVENUCLEIANDTHEDELOCALISEDELECTRONSTHISISSOMETIMESDESCRIBEDAS“ANARRAYOFPOSITIVEIONSINASEAOFELECTRONS“IFYOUAREGOINGTOUSETHISVIEW,BEWAREISAMETALMADEUPOFATOMSORIONSITISMADEOFATOMSEACHPOSITIVECENTREINTHEDIAGRAMREPRESENTSALLTHERESTOFTHEATOMAPARTFROMTHEOUTERELECTRON,BUTTHATELECTRONHASNTBEENLOSTITMAYNOLONGERHAVEANATTACHMENTTOAPARTICULARATOM,BUTITSSTILLTHEREINTHESTRUCTURESODIUMMETALISTHEREFOREWRITTENASNANOTNAMETALLICBONDINGINMAGNESIUMIFYOUWORKTHROUGHTHESAMEARGUMENTWITHMAGNESIUM,YOUENDUPWITHSTRONGERBONDSANDSOAHIGHERMELTINGPOINTMAGNESIUMHASTHEOUTERELECTRONICSTRUCTURE3S2BOTHOFTHESEELECTRONSBECOMEDELOCALIZED,SOTHE“SEA“HASTWICETHEELECTRONDENSITYASITDOESINSODIUMTHEREMAINING“IONS“ALSOHAVETWICETHECHARGEIFYOUAREGOINGTOUSETHISPARTICULARVIEWOFTHEMETALBONDANDSOTHEREWILLBEMOREATTRACTIONBETWEEN“IONS“AND“SEA“MOREREALISTICALLY,EACHMAGNESIUMATOMHASONEMOREPROTONINTHENUCLEUSTHANASODIUMATOMHAS,ANDSONOTONLYWILLTHEREBEAGREATERNUMBEROFDELOCALIZEDELECTRONS,BUTTHEREWILLALSOBEAGREATERATTRACTIONFORTHEMMAGNESIUMATOMSHAVEASLIGHTLYSMALLERRADIUSTHANSODIUMATOMS,ANDSOTHEDELOCALIZEDELECTRONSARECLOSERTOTHENUCLEIEACHMAGNESIUMATOMALSOHASTWELVENEARNEIGHBOURSRATHERTHANSODIUMSEIGHTBOTHOFTHESEFACTORSINCREASETHESTRENGTHOFTHEBONDSTILLFURTHERMETALLICBONDINGINTRANSITIONELEMENTSTRANSITIONMETALSTENDTOHAVEPARTICULARLYHIGHMELTINGPOINTSANDBOILINGPOINTSTHEREASONISTHATTHEYCANINVOLVETHE3DELECTRONSINTHEDELOCALIZATIONASWELLASTHE4STHEMOREELECTRONSYOUCANINVOLVE,THESTRONGERTHEATTRACTIONSTENDTOBETHEMETALLICBONDINMOLTENMETALSINAMOLTENMETAL,THEMETALLICBONDISSTILLPRESENT,ALTHOUGHTHEORDEREDSTRUCTUREHASBEENBROKENDOWNTHEMETALLICBONDISNTFULLYBROKENUNTILTHEMETALBOILSTHATMEANSTHATBOILINGPOINTISACTUALLYABETTERGUIDETOTHESTRENGTHOFTHEMETALLICBONDTHANMELTINGPOINTISONMELTING,THEBONDISLOOSENED,NOTBROKENINTERMOLECULARBONDINGVANDERWAALSFORCESWHATAREINTERMOLECULARATTRACTIONSINTERMOLECULARVERSUSINTRAMOLECULARBONDSINTERMOLECULARATTRACTIONSAREATTRACTIONSBETWEENONEMOLECULEANDANEIGHBOURINGMOLECULETHEFORCESOFATTRACTIONWHICHHOLDANINDIVIDUALMOLECULETOGETHERFOREXAMPLE,THECOVALENTBONDSAREKNOWNASINTRAMOLECULARATTRACTIONSTHESETWOWORDSARESOCONFUSINGLYSIMILARTHATITISSAFERTOABANDONONEOFTHEMANDNEVERUSEITTHETERM“INTRAMOLECULAR“WONTBEUSEDAGAINONTHISSITEALLMOLECULESEXPERIENCEINTERMOLECULARATTRACTIONS,ALTHOUGHINSOMECASESTHOSEATTRACTIONSAREVERYWEAKEVENINAGASLIKEHYDROGEN,H2,IFYOUSLOWTHEMOLECULESDOWNBYCOOLINGTHEGAS,THEATTRACTIONSARELARGEENOUGHFORTHEMOLECULESTOSTICKTOGETHEREVENTUALLYTOFORMALIQUIDANDTHENASOLIDINHYDROGENSCASETHEATTRACTIONSARESOWEAKTHATTHEMOLECULESHAVETOBECOOLEDTO21K252CBEFORETHEATTRACTIONSAREENOUGHTOCONDENSETHEHYDROGENASALIQUIDHELIUMSINTERMOLECULARATTRACTIONSAREEVENWEAKERTHEMOLECULESWONTSTICKTOGETHERTOFORMALIQUIDUNTILTHETEMPERATUREDROPSTO4K269CVANDERWAALSFORCESDISPERSIONFORCESDISPERSIONFORCESONEOFTHETWOTYPESOFVANDERWAALSFORCEWEAREDEALINGWITHONTHISPAGEAREALSOKNOWNAS“LONDONFORCES“NAMEDAFTERFRITZLONDONWHOFIRSTSUGGESTEDHOWTHEYMIGHTARISETHEORIGINOFVANDERWAALSDISPERSIONFORCESTEMPORARYFLUCTUATINGDIPOLESATTRACTIONSAREELECTRICALINNATUREINASYMMETRICALMOLECULELIKEHYDROGEN,HOWEVER,THEREDOESNTSEEMTOBEANYELECTRICALDISTORTIONTOPRODUCEPOSITIVEORNEGATIVEPARTSBUTTHATSONLYTRUEONAVERAGETHELOZENGESHAPEDDIAGRAMREPRESENTSASMALLSYMMETRICALMOLECULEH2,PERHAPS,ORBR2THEEVENSHADINGSHOWSTHATONAVERAGETHEREISNOELECTRICALDISTORTIONBUTTHEELECTRONSAREMOBILE,ANDATANYONEINSTANTTHEYMIGHTFINDTHEMSELVESTOWARDSONEENDOFTHEMOLECULE,MAKINGTHATENDTHEOTHERENDWILLBETEMPORARILYSHORTOFELECTRONSANDSOBECOMESANINSTANTLATERTHEELECTRONSMAYWELLHAVEMOVEDUPTOTHEOTHEREND,REVERSINGTHEPOLARITYOFTHEMOLECULETHISCONSTANT“SLOSHINGAROUND“OFTHEELECTRONSINTHEMOLECULECAUSESRAPIDLYFLUCTUATINGDIPOLESEVENINTHEMOSTSYMMETRICALMOLECULEITEVENHAPPENSINMONATOMICMOLECULESMOLECULESOFNOBLEGASES,LIKEHELIUM,WHICHCONSISTOFASINGLEATOMIFBOTHTHEHELIUMELECTRONSHAPPENTOBEONONESIDEOFTHEATOMATTHESAMETIME,THENUCLEUSISNOLONGERPROPERLYCOVEREDBYELECTRONSFORTHATINSTANTHOWTEMPORARYDIPOLESGIVERISETOINTERMOLECULARATTRACTIONSIMGOINGTOUSETHESAMELOZENGESHAPEDDIAGRAMNOWTOREPRESENTANYMOLECULEWHICHCOULD,INFACT,BEAMUCHMORECOMPLICATEDSHAPESHAPEDOESMATTERSEEBELOW,BUTKEEPINGTHESHAPESIMPLEMAKESITALOTEASIERTOBOTHDRAWTHEDIAGRAMSANDUNDERSTANDWHATISGOINGONIMAGINEAMOLECULEWHICHHASATEMPORARYPOLARITYBEINGAPPROACHEDBYONEWHICHHAPPENSTOBEENTIRELYNONPOLARJUSTATTHATMOMENTAPRETTYUNLIKELYEVENT,BUTITMAKESTHEDIAGRAMSMUCHEASIERTODRAWINREALITY,ONEOFTHEMOLECULESISLIKELYTOHAVEAGREATERPOLARITYTHANTHEOTHERATTHATTIMEANDSOWILLBETHEDOMINANTONEASTHERIGHTHANDMOLECULEAPPROACHES,ITSELECTRONSWILLTENDTOBEATTRACTEDBYTHESLIGHTLYPOSITIVEENDOFTHELEFTHANDONETHISSETSUPANINDUCEDDIPOLEINTHEAPPROACHINGMOLECULE,WHICHISORIENTATEDINSUCHAWAYTHATTHEENDOFONEISATTRACTEDTOTHEENDOFTHEOTHERANINSTANTLATERTHEELECTRONSINTHELEFTHANDMOLECULEMAYWELLHAVEMOVEDUPTHEOTHERENDINDOINGSO,THEYWILLREPELTHEELECTRONSINTHERIGHTHANDONETHEPOLARITYOFBOTHMOLECULESREVERSES,BUTYOUSTILLHAVEATTRACTINGASLONGASTHEMOLECULESSTAYCLOSETOEACHOTHERTHEPOLARITIESWILLCONTINUETOFLUCTUATEINSYNCHRONIZATIONSOTHATTHEATTRACTIONISALWAYSMAINTAINEDTHEREISNOREASONWHYTHISHASTOBERESTRICTEDTOTWOMOLECULESASLONGASTHEMOLECULESARECLOSETOGETHERTHISSYNCHRONIZEDMOVEMENTOFTHEELECTRONSCANOCCUROVERHUGENUMBERSOFMOLECULESTHISDIAGRAMSHOWSHOWAWHOLELATTICEOFMOLECULESCOULDBEHELDTOGETHERINASOLIDUSINGVANDERWAALSDISPERSIONFORCESANINSTANTLATER,OFCOURSE,YOUWOULDHAVETODRAWAQUITEDIFFERENTARRANGEMENTOFTHEDISTRIBUTIONOFTHEELECTRONSASTHEYSHIFTEDAROUNDBUTALWAYSINSYNCHRONIZATIONTHESTRENGTHOFDISPERSIONFORCESDISPERSIONFORCESBETWEENMOLECULESAREMUCHWEAKERTHANTHECOVALENTBONDSWITHINMOLECULESITISNTPOSSIBLETOGIVEANYEXACTVALUE,BECAUSETHESIZEOFTHEATTRACTIONVARIESCONSIDERABLYWITHTHESIZEOFTHEMOLECULEANDITSSHAPEHOWMOLECULARSIZEAFFECTSTHESTRENGTHOFTHEDISPERSIONFORCESTHEBOILINGPOINTSOFTHENOBLEGASESAREHELIUM269CNEON246CARGON186CKRYPTON152CXENON108CRADON62CALLOFTHESEELEMENTSHAVEMONATOMICMOLECULESTHEREASONTHATTHEBOILINGPOINTSINCREASEASYOUGODOWNTHEGROUPISTHATTHENUMBEROFELECTRONSINCREASES,ANDSOALSODOESTHERADIUSOFTHEATOMTHEMOREELECTRONSYOUHAVE,ANDTHEMOREDISTANCEOVERWHICHTHEYCANMOVE,THEBIGGERTHEPOSSIBLETEMPORARYDIPOLESANDTHEREFORETHEBIGGERTHEDISPERSIONFORCESBECAUSEOFTHEGREATERTEMPORARYDIPOLES,XENONMOLECULESARE“STICKIER“THANNEONMOLECULESNEONMOLECULESWILLBREAKAWAYFROMEACHOTHERATMUCHLOWERTEMPERATURESTHANXENONMOLECULESHENCENEONHASTHELOWERBOILINGPOINTTHISISTHEREASONTHATALLOTHERTHINGSBEINGEQUALBIGGERMOLECULESHAVEHIGHERBOILINGPOINTSTHANSMALLONESBIGGERMOLECULESHAVEMOREELECTRONSANDMOREDISTANCEOVERWHICHTEMPORARYDIPOLESCANDEVELOPANDSOTHEBIGGERMOLECULESARE“STICKIER“HOWMOLECULARSHAPEAFFECTSTHESTRENGTHOFTHEDISPERSIONFORCESTHESHAPESOFTHEMOLECULESALSOMATTERLONGTHINMOLECULESCANDEVELOPBIGGERTEMPORARYDIPOLESDUETOELECTRONMOVEMENTTHANSHORTFATONESCONTAININGTHESAMENUMBERSOFELECTRONSLONGTHINMOLECULESCANALSOLIECLOSERTOGETHERTHESEATTRACTIONSAREATTHEIRMOSTEFFECTIVEIFTHEMOLECULESAREREALLYCLOSEFOREXAMPLE,THEHYDROCARBONMOLECULESBUTANEAND2METHYLPROPANEBOTHHAVEAMOLECULARFORMULAC4H10,BUTTHEATOMSAREARRANGEDDIFFERENTLYINBUTANETHECARBONATOMSAREARRANGEDINASINGLECHAIN,BUT2METHYLPROPANEISASHORTERCHAINWITHABRANCHBUTANEHASAHIGHERBOILINGPOINTBECAUSETHEDISPERSIONFORCESAREGREATERTHEMOLECULESARELONGERANDSOSETUPBIGGERTEMPORARYDIPOLESANDCANLIECLOSERTOGETHERTHANTHESHORTER,FATTER2METHYLPROPANEMOLECULESVANDERWAALSFORCESDIPOLEDIPOLEINTERACTIONSAMOLECULELIKEHCLHASAPERMANENTDIPOLEBECAUSECHLORINEISMOREELECTRONEGATIVETHANHYDROGENTHESEPERMANENT,INBUILTDIPOLESWILLCAUSETHEMOLECULESTOATTRACTEACHOTHERRATHERMORETHANTHEYOTHERWISEWOULDIFTHEYHADTORELYONLYONDISPERSIONFORCESITSIMPORTANTTOREALIZETHATALLMOLECULESEXPERIENCEDISPERSIONFORCESDIPOLEDIPOLEINTERACTIONSARENOTANALTERNATIVETODISPERSIONFORCESTHEYOCCURINADDITIONTOTHEMMOLECULESWHICHHAVEPERMANENTDIPOLESWILLTHEREFOREHAVEBOILINGPOINTSRATHERHIGHERTHANMOLECULESWHICHONLYHAVETEMPORARYFLUCTUATINGDIPOLESSURPRISINGLYDIPOLEDIPOLEATTRACTIONSAREFAIRLYMINORCOMPAREDWITHDISPERSIONFORCES,ANDTHEIREFFECTCANONLYREALLYBESEENIFYOUCOMPARETWOMOLECULESWITHTHESAMENUMBEROFELECTRONSANDTHESAMESIZEFOREXAMPLE,THEBOILINGPOINTSOFETHANE,CH3CH3,ANDFLUOROMETHANE,CH3F,AREWHYCHOOSETHESETWOMOLECULESTOCOMPAREBOTHHAVEIDENTICALNUMBERSOFELECTRONS,ANDIFYOUMADEMODELSYOUWOULDFINDTHATTHESIZESWERESIMILARASYOUCANSEEINTHEDIAGRAMSTHATMEANSTHATTHEDISPERSIONFORCESINBOTHMOLECULESSHOULDBEMUCHTHESAMETHEHIGHERBOILINGPOINTOFFLUOROMETHANEISDUETOTHELARGEPERMANENTDIPOLEONTHEMOLECULEBECAUSEOFTHEHIGHELECTRONEGATIVITYOFFLUORINEHOWEVER,EVENGIVENTHELARGEPERMANENTPOLARITYOFTHEMOLECULE,THEBOILINGPOINTHASONLYBEENINCREASEDBYSOME10HEREISANOTHEREXAMPLESHOWINGTHEDOMINANCEOFTHEDISPERSIONFORCESTRICHLOROMETHANE,CHCL3,ISAHIGHLYPOLARMOLECULEBECAUSEOFTHEELECTRONEGATIVITYOFTHETHREECHLORINESTHEREWILLBEQUITESTRONGDIPOLEDIPOLEATTRACTIONSBETWEENONEMOLECULEANDITSNEIGHBOURSONTHEOTHERHAND,TETRACHLOROMETHANE,CCL4,ISNONPOLARTHEOUTSIDEOFTHEMOLECULEISUNIFORMLYINALLDIRECTIONSCCL4HASTORELYONLYONDISPERSIONFORCESSOWHICHHASTHEHIGHESTBOILINGPOINTCCL4DOES,BECAUSEITISABIGGERMOLECULEWITHMOREELECTRONSTHEINCREASEINTHEDISPERSIONFORCESMORETHANCOMPENSATESFORTHELOSSOFDIPOLEDIPOLEINTERACTIONSTHEBOILINGPOINTSARECHCL3612CCCL4768CINTERMOLECULARBONDINGHYDROGENBONDSTHEEVIDENCEFORHYDROGENBONDINGMANYELEMENTSFORMCOMPOUNDSWITHHYDROGENREFERREDTOAS“HYDRIDES“IFYOUPLOTTHEBOILINGPOINTSOFTHEHYDRIDESOFTHEGROUP4ELEMENTS,YOUFINDTHATTHEBOILINGPOINTSINCREASEASYOUGODOWNTHEGROUPTHEINCREASEINBOILINGPOINTHAPPENSBECAUSETHEMOLECULESAREGETTINGLARGERWITHMOREELECTRONS,ANDSOVANDERWAALSDISPERSIONFORCESBECOMEGREATERIFYOUREPEATTHISEXERCISEWITHTHEHYDRIDESOFELEMENTSINGROUPS5,6AND7,SOMETHINGODDHAPPENSALTHOUGHFORTHEMOSTPARTTHETRENDISEXACTLYTHESAMEASINGROUP4FOREXACTLYTHESAMEREASONS,THEBOILINGPOINTOFTHEHYDRIDEOFTHEFIRSTELEMENTINEACHGROUPISABNORMALLYHIGHINTHECASESOFNH3,H2OANDHFTHEREMUSTBESOMEADDITIONALINTERMOLECULARFORCESOFATTRACTION,REQUIRINGSIGNIFICANTLYMOREHEATENERGYTOBREAKTHESERELATIVELYPOWERFULINTERMOLECULARFORCESAREDESCRIBEDASHYDROGENBONDSTHEORIGINOFHYDROGENBONDINGTHEMOLECULESWHICHHAVETHISEXTRABONDINGARENOTETHESOLIDLINEREPRESENTSABONDINTHEPLANEOFTHESCREENORPAPERDOTTEDBONDSAREGOINGBACKINTOTHESCREENORPAPERAWAYFROMYOU,ANDWEDGESHAPEDONESARECOMINGOUTTOWARDSYOUNOTICETHATINEACHOFTHESEMOLECULESTHEHYDROGENISATTACHEDDIRECTLYTOONEOFTHEMOSTELECTRONEGATIVEELEMENTS,CAUSINGTHEHYDROGENTOACQUIREASIGNIFICANTAMOUNTOFPOSITIVECHARGEEACHOFTHEELEMENTSTOWHICHTHEHYDROGENISATTACHEDISNOTONLYSIGNIFICANTLYNEGATIVE,BUTALSOHASATLEASTONE“ACTIVE“LONEPAIRLONEPAIRSATTHE2LEVELHAVETHEELECTRONSCONTAINEDINARELATIVELYSMALLVOLUMEOFSPACEWHICHTHEREFOREHASAHIGHDENSITYOFNEGATIVECHARGELONEPAIRSATHIGHERLEVELSAREMOREDIFFUSEANDNOTSOATTRACTIVETOPOSITIVETHINGSCONSIDERTWOWATERMOLECULESCOMINGCLOSETOGETHERTHEHYDROGENISSOSTRONGLYATTRACTEDTOTHELONEPAIRTHATITISALMOSTASIFYOUWEREBEGINNINGTOFORMACOORDINATEDATIVECOVALENTBONDITDOESNTGOTHATFAR,BUTTHEATTRACTIONISSIGNIFICANTLYSTRONGERTHANANORDINARYDIPOLEDIPOLEINTERACTIONHYDROGENBONDSHAVEABOUTATENTHOFTHESTRENGTHOFANAVERAGECOVALENTBOND,ANDAREBEINGCONSTANTLYBROKENANDREFORMEDINLIQUIDWATERIFYOULIKENTHECOVALENTBONDBETWEENTHEOXYGENANDHYDROGENTOASTABLEMARRIAGE,THEHYDROGENBONDHAS“JUSTGOODFRIENDS“STATUSONTHESAMESCALE,VANDERWAALSATTRACTIONSREPRESENTMEREPASSINGACQUAINTANCESWATERASA“PERFECT“EXAMPLEOFHYDROGENBONDINGNOTICETHATEACHWATERMOLECULECANPOTENTIALLYFORMFOURHYDROGENBONDSWITHSURROUNDINGWATERMOLECULESTHEREAREEXACTLYTHERIGHTNUMBERSOFHYDROGENSANDLONEPAIRSSOTHATEVERYONEOFTHEMCANBEINVOLVEDINHYDROGENBONDINGTHISISWHYTHEBOILINGPOINTOFWATERISHIGHERTHANTHATOFAMMONIAORHYDROGENFLUORIDEINTHECASEOFAMMONIA,THEAMOUNTOFHYDROGENBONDINGISLIMITEDBYTHEFACTTHATEACHNITROGENONLYHASONELONEPAIRINAGROUPOFAMMONIAMOLECULES,THEREARENTENOUGHLONEPAIRSTOGOAROUNDTOSATISFYALLTHEHYDROGENSINHYDROGENFLUORIDE,THEPROBLEMISASHORTAGEOFHYDROGENSINWATER,THEREISEXACTLYTHERIGHTNUMBEROFEACHWATERCOULDBECONSIDEREDASTHE“PERFECT“HYDROGENBONDEDSYSTEMMORECOMPLEXEXAMPLESOFHYDROGENBONDINGTHEHYDRATIONOFNEGATIVEIONSWHENANIONICSUBSTANCEDISSOLVESINWATER,WATERMOLECULESCLUSTERAROUNDTHESEPARATEDIONSTHISPROCESSISCALLEDHYDRATIONWATERFREQUENTLYATTACHESTOPOSITIVEIONSBYCOORDINATEDATIVECOVALENTBONDSITBONDSTONEGATIVEIONSUSINGHYDROGENBONDSTHEDIAGRAMSHOWSTHEPOTENTIALHYDROGENBONDSFORMEDTOACHLORIDEION,CLALTHOUGHTHELONEPAIRSINTHECHLORIDEIONAREATTHE3LEVELANDWOULDNTNORMALLYBEACTIVEENOUGHTOFORMHYDROGENBONDS,INTHISCASETHEYAREMADEMOREATTRACTIVEBYTHEFULLNEGATIVECHARGEONTHECHLORINEHOWEVERCOMPLICATEDTHENEGATIVEION,THEREWILLALWAYSBELONEPAIRSTHATTHEHYDROGENATOMSFROMTHEWATERMOLECULESCANHYDROGENBONDTOHYDROGENBONDINGINALCOHOLSANALCOHOLISANORGANICMOLECULECONTAININGANOHGROUPANYMOLECULEWHICHHASAHYDROGENATOMATTACHEDDIRECTLYTOANOXYGENORANITROGENISCAPABLEOFHYDROGENBONDINGSUCHMOLECULESWILLALWAYSHAVEHIGHERBOILINGPOINTSTHANSIMILARLYSIZEDMOLECULESWHICHDONTHAVEANOHORANNHGROUPTHEHYDROGENBONDINGMAKESTHEMOLECULES“STICKIER“,ANDMOREHEATISNECESSARYTOSEPARATETHEMETHANOL,CH3CH2OH,ANDMETHOXYMETHANE,CH3OCH3,BOTHHAVETHESAMEMOLECULARFORMULA,C2H6OTHEYHAVETHESAMENUMBEROFELECTRONS,ANDASIMILARLENGTHTOTHEMOLECULETHEVANDERWAALSATTRACTIONSBOTHDISPERSIONFORCESANDDIPOLEDIPOLEATTRACTIONSINEACHWILLBEMUCHTHESAMEHOWEVER,ETHANOLHASAHYDROGENATOMATTACHEDDIRECTLYTOANOXYGENANDTHATOXYGENSTILLHASEXACTLYTHESAMETWOLONEPAIRSASINAWATERMOLECULEHYDROGENBONDINGCANOCCURBETWEENETHANOLMOLECULES,ALTHOUGHNOTASEFFECTIVELYASINW