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1、MATTERISTHESTUFFAROUNDYOUNotveryclear,butit'strue.Anythingthattakesupspaceorhasamassofanykindismatter.Everythingyoucantouchismadeofmatter.Ifitismadeofanything,thatanythingismatter.Everythingyouwilllearnaboutchemistrywillallbebasedonhowmatterreactsandcombines.Matterhasmanypro
2、perties.ItcanhavePHYSICALpropertieslikedifferentdensities,meltingpoints,boilingpoints,freezingpoints,colororsmells.TherearealsoCHEMICALpropertiesthatdefinematter.Agoodexampleofchemicalpropertiesisthewayelementscombinewitheachotherinreactions.Thebigthingtoremember...Mattercan
3、changeintwomajorways,physicallyandchemically.Ifwearetounderstandhowmatterisbehavingwemustunderstandwhatishappeningatmatter’smostbasiclevel-thesmallestparticleofmatterinvolvedinthechange(akaatomsandmolecules).MatterinMotionMotionisacommoncharacteristicoflargescalesamplesofmat
4、terthataregivensuitablepushesandpulls(alsoknownasforces).Tennisballs,automobiles,raindrops,popcorn,anddustparticlesinarayofsunlightcanallbeeasilyvisualizedinstatesofmotion.Butwewilllearnthatevenlargescaleobjectsseeminglyatrestarestillinmotion!Todevelopsuchaviewwewillexaminet
5、hebehaviorofmattermoreclosely-specificallyGASES.Recallthattherearethreemainstatesofmatter(withafourthstatethatisnottoocommon):SOLIDS,LIQUIDS,GASES,andPLASMAS.Thesestatescanalsobecalled“PHASES”.Wealreadyknowthatmatterismadeofcombinationsofelementsandcompoundsand(accordingtoDa
6、lton)ultimately-ATOMS!Thephaseofasubstancedescribesaphysicalpropertyofmatter.Thekeywordhereisphysicalandnotchemicalbecausematterwillmovefromonephasetoanotherbyphysicalmeans.Byaddingheatortakingheataway,wechangethetemperatureofthesubstanceanditsphysicalstate,butthechemicalcom
7、positionandchemicalpropertiesofthesubstancestaythesame(usually).Meltingisagoodexampleofachangeofstate.Wecanproceedfromasolidstateofmattertoaliquidstateofmattertoagas.Dependingoncertainconditions(liketemperatureandpressure),manydifferenttypesofmattercanexistinallthreestates.T
8、hecolderasampleisthemorelikelyitistobeasolid;thehotteritis,themorelikelyiti
