问题标题:
【求关于水晶的英文短文RT,五六百个单词左右,最好有中文,没有也行不要太长啊】
问题描述:
求关于水晶的英文短文
RT,五六百个单词左右,最好有中文,没有也行
不要太长啊
李唐回答:
ThePhysicsofaCrystal
Mostsimplechemicalcompoundsconsistofcrystals.Ifyouweretoexaminealumpofcrystallinematerialveryclosely,youwouldbeabletoseetinyindividualcrystals.Allcrystalshaveadefinitegeometricshape,determinedbythewaytheatomsarelinkedtogether.
Mineralogistsrecognize32differentclassesofcrystal,whicharegroupedintosevencrystalsystems.Crystalsystemsaredescribedbytheiraxis,whichareimaginarylinesthatjointhecenterofopposingfacesofacrystal.Forexample,ifacubiccrystalhasthreesetsofopposingfaces,ithasthreeaxes.Theyareallofequallengthandareallatrightanglestoeachother.
Cubiccrystalsaredescribedasbeingisometric,butnotallisometriccrystalsareplaincubes.Ifthecornersofacubearecutoff,theresultisapolyhedronwithsixoctagonalfacedandeighttriangularones.
Asidefromtheisometricsystem,thereisalso;atetragonal,orthorhombic,monoclinic,triclinicandhexagonalsystem.
Crystalsmayformwhenasolutionofasubstanceevaporates.Crystalsmayalsoformwhenavaporormoltensubstancesolidifies.
Allotropesaredifferentformsofthesameelement.ForExample,oxygenhastwoallotropes,normaloxygenandozone.Purecarbonalsohastwoallotropes,diamondandgraphite.Acrystalofdiamondisinfactasinglegiantmoleculeinwhicheverycarbonatomislinkedtofourother,byfourequal,strongbonds.Thesebondsarearrangedtetrahedrallyroundeachatomandtherearenoplanesalongwhichthegiantmoleculecaneasilybesplit.Thisqualityiswhatgivesdiamonditstremendoushardness.
Graphiteontheotherhand,consistsofflatsheetsofcarbonatomsarrangedinadjoiningrings.Eachcarbonatomislinkedtothreeothersbyfairlystrongbondthatalllieinthesameplane.Thesecaneasilybeovercome,allowingthesheetstoslideovereachother.Asaresult,graphiteisasoftslipperysubstancethatcanbeusedasalubricant.
【稍微短点了…………建议lz自己去外国搜索引擎找一找,比如yahoo、Google之类的,可以搜essaysoncrystal……稍微耐心点看,总能找到满意的^-^】
查看更多
八字精批
八字合婚
八字起名
八字财运
2024运势
测终身运
姓名详批
结婚吉日