chemistry glossary.docx
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chemistry glossary.docx
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chemistryglossary
acceleration
Measureofhowfastvelocityischanging,sowecanthinkofitasthechangeinvelocityoverchangeintime.Themostcommonuseofaccelerationisaccelerationduetogravity,whichcanalsoappearasthegravitationalconstant(9.8m/s2).
acid
CompoundthatgivesoffH+ ionsinsolution.
acidic
DescribesasolutionwithahighconcentrationofH+ ions.
anion
Ionswithanegativecharge.
anode
Theelectrodewhereelectronsarelost(oxidized)inredoxreactions.
area
Measuresthesizeofasurfaceusinglengthmeasurementsintwodimensions.
associativity
Apropertyinmathwhichstatesthat:
(A+B)+C=A+(B+C)and(A*B)*C=A*(B*C).
atmospheres
Commonunitsformeasuringpressure.
atom
Thesmallestobjectthatretainspropertiesofanelement.Composedofelectronsandanucleus(containingprotonsandneutrons).
atomicnumber
Numberofprotonsinanelement.
Avogadro'snumber
Numberrepresentingthenumberofmoleculesinone
(1)mole:
6.022*1023.
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B
base
Substancewhichgivesoffhydroxideions(OH-)insolution.
basic
Havingthecharacteristicsofabase.
Bohr'satom
Bohrmadesignificantcontributionstotheatom.Heunderstoodthelinespectra--thereasonwhyonlycertainwavelengthsareemittedwhenatomsjumpdownlevels.
buffersolutions
SolutionsthatresistchangesintheirpH,evenwhensmallamountsofacidorbaseareadded.
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C
catalyst
Substancethatspeedsupachemicalprocesswithoutactuallychangingtheproductsofreaction.
cathode
Electrodewhereelectronsaregained(reduction)inredoxreactions.
cations
Ionwithapositivecharge.
centralatom
InaLewisstructure,usuallytheatomthatistheleastelectronegative.
charge
Describesanobject'sabilitytorepelorattractotherobjects.Protonshavepositivechargeswhileelectronshavenegativecharges.Likechargesrepeleachotherwhileoppositecharges,suchasprotonsandelectrons,attractoneanother.
chemicalchanges
Processesoreventsthathavealteredthefundamentalstructureofsomething.
chemicalequation
Anexpressionofafundamentalchangeinthechemicalsubstances.
closure
AmathematicaltermwhichsaysthatifyouoperatedonanytworealnumbersAandBwith+,-,*or/,yougetarealnumber.
colligativeproperties
Propertiesofasolutionthatdependonlyonthenumberofparticlesdissolvedinit,notthepropertiesoftheparticlesthemselves.Themaincolligativepropertiesaddressedatthiswebsiteareboilingpointelevationandfreezingpointdepression.
combustion
Whensubstancescombinewithoxygenandreleaseenergy.
commutativity
Amathpropertywhichstates:
A+B=B+AandA*B=B*A.
compound
Twoormoreatomsjoinedtogetherchemically,withcovalentorionicbonds.
concentration
Theamountofsubstanceinaspecifiedspace.
conjugateacid
AsubstancewhichcanloseaH+ iontoformabase.
conjugatebase
AsubstancewhichcangainaH+ iontoformanacid.
covalentbonds
Whentwoatomsshareatleastonepairofelectrons.
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D
daughterisotope
Inanuclearequationthecompoundremainingaftertheparentisotope(theoriginalisotope)hasundergonedecay.Acompoundundergoingdecay,suchasalphadecay,willbreakintoanalphaparticleandadaughterisotope.
decay
Changeofanelementintoadifferentelement,usuallywithsomeotherparticle(s)andenergyemitted.
decimal
Thenumberofdigitstotherightofthedecimalpointinanumber.
dense
Acompactsubstanceorasubstancewithahighdensity.
density
Massperunitvolumeofasubstance.
dipole-dipoleforces
Intermolecularforcesthatexistbetweenpolarmolecules.Activeonlywhenthemoleculesareclosetogether.Thestrengthsofintermolecularattractionsincreasewhenpolarityincreases.
dispersionforces(alsocalledLondondispersionforces)
Dispersionisanintermolecularattractionforcethatexistsbetweenallmolecules.Theseforcesaretheresultofthemovementofelectronswhichcauseslightpolarmoments.Dispersionforcesaregenerallyveryweakbutasthemolecularmassincreasessodoestheirstrength.
dissociation
Breakingdownofacompoundintoitscomponentstoformionsfromanionicsubstance.
distributivity
Amathpropertywhichstates:
A*(B+C)=(A*B)+(A*C).
doublebond
Whenanatomisbondedtoanotheratombytwosetsofelectronpairs.
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E
effusion
Movementofgasmoleculesthroughasmallopening.
electrochemicalcell
Givesanelectriccurrentwithasteadyvoltageasaresultofanelectrontransferreaction.
electrodes
Devicethatmoveselectronsintooroutofasolutionbyconduction.
electrolysis
Changingthechemicalstructureofacompoundusingelectricalenergy.
electromagneticspectrum
Completerangeofwavelengthswhichlightcanhave.Theseincludeinfrared,ultraviolet,andallothertypesofelectromagneticradiation,aswellasvisiblelight.
electron
Oneofthepartsoftheatomhavinganegativecharge.Indivisibleparticlewithachargeof-1.
electrongeometry
Structureofacompoundbasedonthearrangementofitselectrons.
electronegativity
Measureofasubstance'sabilitytoattractelectrons.
electrostaticforces
Forcesbetweenchargedobjects.
element
Substanceconsistingofonlyonetypeofatom.
empiricalformula
Formulashowingthesimplestratioofelementsinacompound.
endothermic
Processthatabsorbsheatfromitssurroundingsasthereactionproceeds.
energy
Abilitytodowork.
enthalpy
Changeinheatatconstantpressure.
entropy
Measureofthedisorderofasystem.
equilibrium
Whenthereactantsandproductsareinaconstantratio.Theforwardreactionandthereversereactionsoccuratthesameratewhenasystemisinequilibrium.
equilibriumconstant
Valuethatexpresseshowfarthereactionproceedsbeforereachingequilibrium.Asmallnumbermeansthattheequilibriumistowardsthereactantssidewhilealargenumbermeansthattheequilibriumistowardstheproductsside.
equilibriumexpressions
Theexpressiongivingtheratiobetweentheproductsandreactants.Theequilibriumexpressionisequaltotheconcentrationofeachproductraisedtoitscoefficientinabalancedchemicalequationandmultipliedtogether,dividedbytheconcentrationoftheproductofreactantstothepoweroftheircoefficients.
equivalencepoint
Occurswhenthemolesofacidequalthemolesofbaseinasolution.
exothermic
Processthatgivesoffheattotheenvironment.
exponentiation
Raisingsomethingtoapower.
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F
force
Anentitythatwhenappliedtoamasscausesittoaccelerate.SirIsaacNewton'sSecondLawofMotionstates:
themagnitudeofaforce=mass*acceleration.
freeelectron
Electronwhichisnotattachedtoanucleus.
frequency
Numberofeventsinagivenunitoftime.Whendescribingamovingwave,meansthenumberofpeakswhichwouldpassastationarypointinagivenamountoftime.
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G
Geigercounter
Instrumentthatmeasuresradiationoutput.
Gibb'sfreeenergy
Theenergyofasystemthatisavailabletodoworkatconstanttemperatureandpressure.
Graham'slaw
Therateofdiffusionofagasisinverselyproportionaltothesquarerootofitsmolarmass.
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H
halflife
Theamountoftimeittakesforhalfaninitialamounttodisintegrate.
Heisenberguncertaintyprinciple
Thisprinciplestatesthatitisnotpossibletoknowaparticle'slocationandmomentum precisely atanytime.
hydrogenbonding
Strongtypeofintermoleculardipole-dipoleattraction.OccursbetweenhydrogenandF,OorN.
hydrolysis
Thereactionsofcationswithwatertoproduceaweakbaseorofanionstoproduceaweakacid.
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I
idealgaslaw
PV=nRT
Describestherelationshipbetweenpressure(P),temperature(T),volume(V),andmolesofgas(n).Thisequationexpressesbehaviorapproachedbyrealgasesatlowpressureandhightemperature.
identity
Amathpropertywhichstates:
A+0=AandA*1=A.
intermolecularforces
Forcesbetweenmolecules.
intramolecularforces
Forceswithinmolecules.Forcescausedbytheattractionandrepulsionofchargedparticles.
inverse
Amathpropertywhichstates:
A+(-A)=0andA*(1/A)=1
ion
Removingoraddingelectronstoanatomcreatesanion(achargedobjectverysimilartoanatom).
ion-dipoleforces
Intermolecularforcethatexistsbetweenchargedparticlesandpartiallychargedmolecules.
ionicbonds
Whentwooppositelychargedatomsshareatleastonepairofelectronsbuttheelectronsspendmoretimenearoneoftheatomsthantheother.
ionizationenergy
Energyrequiredtoremoveanelectronfromaspecificatom.
ionizes
Whenasubstancebreaksintoitsioniccomponents.
isotopes
Elementswiththesamenumberofprotonsbuthavedifferentnumbersofneutrons,andthusdifferentmasses.
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K
Kelvin
TheSIUnitoftemperature.ItisthetemperatureindegreesCelsiusplus273.15.
kineticenergy
Energyanobjecthasbecauseofitsmassandvelocity.Objectsthatnotmovinghavenokineticenergy.(KineticEnergy=0.5*mass*velocity2.
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L
LeChatlier'sprinciple
Statesthatasystematequilibriumwillopposeanychangeintheequilibriumconditions.
Lewisstructures
Awayofrepresentingmolecularstructuresbasedonvalenceelectrons.
limitingreagent
Thereactantthatwillbeexhaustedfirst.
linespectra
Spectrageneratedbyexcitedsubstances.Consistsofradiationwithonlyspecificwavelengths.
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M
massnumber
Thenumberofprotonsandneutronsinanatom.
mixture
Composedoftwoormoresubstances,buteachkeepsitsoriginalproperties.
molality
Thenumberofmolesofsolute(thematerialdissolved)perkilogramofsolvent(whatthesoluteisdissolvedin).
molar
Antermexpressingmolarity,thenu
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