材料科学与工程导论双语课件教学课件 作者 陈克正 王玮 刘春延 等编Chapter 2.ppt

《材料科学与工程导论双语课件教学课件 作者 陈克正 王玮 刘春延 等编Chapter 2.ppt》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、INTRODUCTIONTOMATERIALSSCIENCEANDENGINEERINGQingdaoUniversityofScience&TechnologyKezhengChenWeiWangChuntingLiu国家级双语教学示范课程ISSUESTOADDRESS...CHAPTER2THESTRUCTUREOFCRYSTALLINESOLIDS•Whatpromotesbonding?•Whattypesofbondsarethere?•Whatpropertiesareinferredfrombonding?2.1AtomicStructureandInteratomi

2、cBondingATOMS=(PROTONS+NEUTRONS)+ELECTRONSNUCLEARProtons:positivelychargedElectrons:negativelychargedNeutrons:electricallyneutral2.1.1FundamentalConceptsAtomicnumber(Z)=ThenumberofprotonsAtomicmass(A)=TotalmassofprotonsandneutronsIsotope(同位素)–AtomshavethesameZbutdifferentAor#ofneutrons#ofprot

3、onsisusedtoidentifyelements(Z)#ofneutronsisusedtoidentifyisotopesIsotopesarewrittenasfollows:AXZ,i.e.1H1(protium),2H1(deuterium),3H1(tritium).A——atomicmassZ——atomicnumber2.1.1FundamentalConceptsMoleconcept:theatomicweightisoftenexpressedinmasspermole.ThenumberofatomsinamoleiscalledtheAvogadro’

4、snumber,Nav=6.023×1023.Netforce(FN)=Attractive(FA)+Repulsive(FR)r=r0，FN=0FAFRFN+-Interatomicseperation(r)Fr=∞，FNignored；r↓,

5、FA

6、,

7、FR

8、,r0

9、FA

10、>

11、FR

12、,FNisattractiveforce；r=r0(r0=~0.3nm),

13、FA

14、=

15、FR

16、,FN=0;r

17、FR

18、>

19、FA

20、,FNisrepulsiveforce2.1.2BondingForcesandEnergiesEAER+-ENrEN=EA+ERr0

21、acementisinthesamedirectionwithFN,kineticE↑,EN↓;r=r0，ENminimum(=E0);r

22、ryinteratomicbonds(Physical)VanderWaalsForcesHydrogenBonds•Requireselectrontransfer.•Largedifferenceinelectronegativityrequired.2.1.3.1IonicBonding•Alwaysoccursbetween+and-ions.Electronegativity:Theabilityofanatomtoobtainanelectron.•Predominantbondingbetweenmetalelementsandnonmetalelements(inc

23、eramics)2.1.3.1IonicBondingNondirectional:themagnitudeofthebondisequalinalldirectionsaroundanionRelativelylargebondingenergies(600-1500KJ/mol)RelativelylargebondingenergiesIonicCrystals2.Insulatorofheatandelectricity1.Stable,hardwithhig