托福阅读素材：元素周期表的发展

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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