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1、Covalentbonding1.教学内容Covalency;2kindofcovalentbond;Lonepairs;Coordinatebonds2.学生情况Grade11.Thestudentsshouldhavealreadycoveredinpreviouslessons:atomicstructure,electronicconfigurations,Ionicbonding3.教学目标Identify,define,andexplain：thecovalentbond,covalency,non-bonding,dativecov
2、alencyClassifythetwokindsofcovalentbond.Distinguishnon-bondingandcoordinatebonds4.专业术语Covalentbonding,electrostatic,nuclei,orbitals,overlap,Sigmabonds,Pibonds,lonepairs,dativecovalency,coordinatebonds5.教学方法Lectureandexperiment6.教学材料和资料TextReference:CovalentbondingSection:3.3(
3、page17)7.时间安排45min8.教学过程(1)准备(2min)Writeoutthekeytermsofthistopic,andreadtwice(2)过程(40min)① 引入Quickreviewoftheionicbonding:summarythecharacteristicsofionicbondingStart-upProblem:IsittheionicbondingbetweentwoatomsintheH2molecule?(Studentsdiscussingroupsof5andonerepresentatives
4、hareshisgroups’sopinions)Wecanconcludethatthebondisn’tionicbonding。② 阐述Definition:theCovalentbondFirst,weshouldknowthatthecovalentbondisthebondingbetweentwonon-metallicatoms.Pleasepayattentiontoitsapplicationrange.Letuslookatitsdefinition:Acovalentbondistheelectrostaticforceo
5、fattractionthattwoneighbouringnucleihaveforalocalisedpairofelectronssharedbetweenthem.Forexample:H2hasbeenformedbecausethetwoHatomsshareelectrons.Theatomsaresaidtobejoinedbyacovalentbond.Acovalentbondisformedbetweentwoatomswhentheatomssharevalenceelectrons.Howtoformacovalentb
6、ond?Covalentbondsformwhentheorbitalsoftwoneighbouringatomsoverlapsothatbothnucleiattractthepairselectronsbetweenthem.Howdoweclassifycovalentbond?(StudentstotakesomeexamplesofSigmabondsandPibonds)Sigmabonds:Whentheorbitalsfromtwoatomsoverlapalongthelinedrawnthroughthenuclei,as
7、igmabondforms.Pibonds:Sometimes,afterasigmabondhasformedbetweentwoatoms,theporbitalsofthetwoatomsalsooverlapalongaboveandbelowthelinedrawnthroughthetwonuclei,andanotherbondforms.(Examples-N2,C6H6,O3,CO2)ExperimentsWithball-and-stickmodel,teacherdemonstrateTheformationprocesso
8、ftwokindofcovalentbond.Definition:CovalencyUsually,thenumberofbondsf
