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时间:2020-09-20
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1、ChapterIStructure&Bonding1-1ElectronConfigurationsofAtoms1-2ChemicalBonding&Valence1-3ChargeDistributioninMolecules1-4TheShapeofMolecules1-5Isomers1-6Resonance1-71-8AtomicandMolecularOrbitalsThestudyoforganicchemistrymustatsomepointextendtothemolecularlevel,forthephysica
2、landchemicalpropertiesofasubstanceareultimatelyexplainedintermsofthestructureandbondingofmolecules.Thismodule模块introducessomebasicfactsandprinciplesthatareneededforadiscussionoforganicmolecules.1-1ElectronicConfigurationsElectronConfigurationsinthePeriodicTableTheperiodi
3、ctableshownhereisseverelytruncated.Thereare,ofcourse,overeightyotherelements.Thehalogensareoneelectronshortofavalenceshelloctet,andareamongthemostreactiveoftheelements.Intheirchemicalreactionshalogenatomsachieveavalenceshelloctetbycapturingorborrowingtheeighthelectronfro
4、manotheratomormolecule.Thealkalimetalsarealsoexceptionallyreactive,butfortheoppositereason.Theseatomshaveonlyoneelectroninthevalenceshell,andonlosingthiselectronarriveatthelowershellvalenceoctet.Asaconsequenceofthiselectronloss,theseelementsarecommonlyencounteredascation
5、s(positivelychargedatoms).1-2-1IonicBondingWhensodiumisburnedinachlorineatmosphere,itproducessodiumchloride.Thishasahighmeltingpoint(800ºC)anddissolvesinwatertogiveaconductingsolution.Sodiumchlorideisanioniccompound,inwhichanelectronofsodiumatomwastransferredtoachlorinea
6、tomandgeneratesasodiumcationandachlorideanion.Electrostaticattractionresultsintheseoppositelychargedionspackingtogetherinalattice.Theattractiveforcesholdingtheionsinplacecanbereferredtoasionicbonds.1-2ChemicalBondingandValence1-2-2CovalentBondingWaterisaliquidatroomtempe
7、rature;carbondioxideandcarbontetrafluoridearegases.Noneofthesecompoundsiscomposedofions.Adifferentattractiveinteractionbetweenatoms,calledcovalentbonding,isinvolvedhere.Covalentbondingoccursbysharingofvalenceelectrons,ratherthananoutrightelectrontransfer.Similaritiesinph
8、ysicalproperties(theyareallgases)suggestthatthediatomicelementsH2,N2,O2,F2&Cl2alsohavecovalentbonds.Car
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