欢迎来到天天文库
浏览记录
ID:33158583
大小:116.50 KB
页数:11页
时间:2019-02-21
《chapter 8 molecular shape:8章分子形状》由会员上传分享,免费在线阅读,更多相关内容在应用文档-天天文库。
1、Chapter8MolecularShapeObjectives8-1TheShapeofSmallMolecules·DescribetheVSEPRtheory·Identifythecommonshapesofsmallmolecules8-2Polarity·Explainwhatdeterminesthepolarityofamolecule·Explainwhywaterisapolarmolecule118-1TheShapeofSmallMoleculesWhataresomehouseholduses
2、forwater?Whatissomewaythatwaterhasbeenamemorablepartofanexperienceinyourlife?Whatpropertiesofwatermadethispossible?MolecularGeometry·Howbondsarearrangedinamoleculedeterminestheshapeofamolecule·Structuralformuladoesnotindicateshapeofamolecule.DrawLewisdotstructur
3、eforammonia,NH3ØStructuralformuladoesnotshowhowbondsarearrangedinspace(3D)·Ball&Stickmodels-areusedtoindicatemolecularshape.Ballsarenuclei&sticksarebonds.Seefigures8.4,8.5&8.7·Therearemanyshapesofsmallmoleculesbutallaresymmetrical-meaningthebondsandatomsarearran
4、gedinaregularpatternwithequaldistancesseparatingtheatomsthatarenotbondedtogether.WHY?ØValenceshellelectronsrepeleachotherbecauseofsimilarelectricalcharge11·VSEPR(valenceshellelectronpairrepulsion)Theory-inasmallmolecule,thepairsofvalenceelectronsarearrangedasfar
5、apartfromeachotheraspossible.ØThisisduetotherepulsionoflikechargesone-ØEachpairofvalenceelectronswearetalkingaboutisachemicalbondØTherearesomeexceptionswithtransitionmetalsbutthisisgenerallytrueØThismakesthemolecularshapeofsmallmoleculespredictable·5mostcommonsh
6、apes1)Lineara.Moleculesw/2atoms,IE>O2,HClb.Manymoleculesw/3atoms,IE>CO2c.Bondangle-geometricanglebetween2adjacentbonds.ForCO2(linearshape)bondangleis180°,sothatthevalenceelectronscanbeasfarapartfromeachotheraspossible.BuildCO22)TrigonalPlanar-4atomsa.Meaningtria
7、ngular&flatb.BCl3orborontrichloride-i.the3Clatomsarearrangedintheshapeofanequilateraltriangle(allsidesareequal)ii.boronisinthecenterandhasnounsharedelectronpairs(3valencee-).Thisistypicaloftrigonalplanarshapedmolecules.iii.bondangleis120°11BuildBCl31)Tetrahedal-
8、5atomsa.Tetrahedal=foursurfacesb.=methane,animportantfuel&principlecomponentofnaturalgasc.Bondangle=109.5°ifonly2dimensionalgreatestanglewouldbe90°BuildCH4Configurati
此文档下载收益归作者所有