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ID:19511851
大小:2.80 MB
页数:7页
时间:2018-10-03
《托福阅读素材:元素周期表的发展》由会员上传分享,免费在线阅读,更多相关内容在工程资料-天天文库。
1、智课网TOEFL备考资料forthequalityofreviewsandreview.Article26threview(a)theCCRAcompliance,whethercopiesofchecks;(B)whetherdoubleinvestigation;(C)submissionofprogramcompliance,investigationorexaminationofwhetherviewsareclear;(D)theborrower,guarantorloans托福阅读素材:元素周期表的发
2、展摘要:托福阅读素材:元素周期表的发展,下面是小马过河为同学们搜集整理的托福阅读素材的相关信息,小马小编整理过来,供同学们参考。托福化学类阅读文章翻译,DevelopmentofthePeriodicTable元素周期表的发展文章词汇words元素element族group原子序数atomicnumber同位素isotope化学性质chemicalproperty物理性质physicalproperty原子atom原子核nucleus质子proton中子neutronforthequalityofreviewsa
3、ndreview.Article26threview(a)theCCRAcompliance,whethercopiesofchecks;(B)whetherdoubleinvestigation;(C)submissionofprogramcompliance,investigationorexaminationofwhetherviewsareclear;(D)theborrower,guarantorloans电子electron稀有气体raregases碱金属alkalimetal文章翻译translat
4、ion一、元素周期表出现的背景Theperiodictableisachartthatreflectstheperiodicrecurrenceofchemicalandphysicalpropertiesoftheelementswhentheelementsarearrangedinorderofincreasingatomicnumber(thenumberofprotonsinthenucleus).Itisamonumentalscientificachievement,anditsdevelopmen
5、tillustratestheessentialinterplaybetweenobservation,prediction,andtestingrequiredforscientificprogress.Inthe1800'sscientistsweresearchingfornewelements.Bythelate1860'smorethan60chemicalelementshadbeenidentified,andmuchwasknownabouttheirdescriptivechemistry.Va
6、riousproposalswereputforthtoarrangetheelementsintogroupsbasedonsimilaritiesinchemicalandphysicalproperties.Thenextstepwastorecognizeaconnectionbetweengroupproperties(physicalorchemicalsimilarities)andatomicmass(themeasuredmassofanindividualatomofanelement).Wh
7、entheelementsknownatthetimewereorderedbyincreasingatomicmass,itwasfoundthatsuccessiveelementsbelongedtodifferentchemicalgroupsandthattheorderofthegroupsinthissequencewasfixedandrepeateditselfatregularintervals.ItwasanaturalIdeatobreakuptheseriesofelementsatth
8、epointswherethesequenceofchemicalgroupstowhichtheelementsbelongedbegantorepeatitself.Thuswhentheseriesofelementswaswrittensoastobeginanewhorizontalrowwitheachalkalimetal,elementsofthesame
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