8
The atomic number of hydrogen is 1. The standard atomic weight of hydrogen is 1.008 (this value is not given here as an expectation interval, as it is in elements below). Atomic weight is the same as relative atomic mass . The atomic weights of samples of hydrogen will vary according to their content of heavy hydrogen (deuterium), and this will in turn depend upon where the samples are collected. Relative atomic mass From Wikipedia, the free encyclopedia Relative atomic mass (symbol: A r ) is a dimensionless physical quantity, the ratio of the average mass of atoms of an element (from a single given sample or source) to 1 ∕ 12 of the mass of an atom of carbon12 (known as the unified atomic mass unit). [1][2] The relative atomic mass is a statistical term, referring to an abundanceweighted figure involving measurement of many atoms. As in all related terms, the word "relative" refers to making the figure relative to carbon12, so that the final figure is dimensionless. The term relative atomic mass is exactly equivalent to atomic weight, which is the older term. In technical usage, these values are sample specific (i.e., element sourcespecific) when a natural element source is composed of more than one isotope. Thus, two samples of a chemical element which is naturally found as being composed of more than one isotope, collected from two substantially different sources, are expected to give slightly different relative atomic masses (atomic weights), because isotopic concentrations typically vary slightly due to the history (origin) of the source. These values differences are real and repeatable, and can be used to identify specific samples. For example, a sample of elemental carbon from volcanic methane will have a different relative atomic mass (atomic weight) than one collected from plant or animal tissues (for more, see isotope geochemistry). In short, the atomic weight (relative atomic mass) of carbon varies slightly from place to place and from source to source, a fact that can be useful. However, a typical (standard) figure also can be useful, as follows. Both the terms relative atomic mass and atomic weight are sometimes loosely used to refer to a technically different standardized expectation value, called the standard atomic weight. This value is the mean value of atomic weights of a number of "normal samples" of the element in question. For this definition, "[a] normal sample is any reasonably possible source of the element or its compounds in commerce for industry and science and has not been subject to significant modification of isotopic composition within a geologically brief period." [3] These standard atomic weights are published at regular intervals by the Commission on Isotopic Abundances and Atomic Weights of the International Union of Pure and Applied Chemistry (IUPAC) [4][5] The "standard" values are intended as mean values that compensate for small variances in the isotopic composition of the chemical elements across a range of ordinary samples on Earth, and thus to be applicable to normal laboratory materials. However, they may not accurately reflect values from samples from unusual locations or extraterrestrial objects, which often have more widely variant isotopic compositions. The standard atomic weights are reprinted in a wide variety of textbooks, commercial catalogues, Periodic Table wall charts etc., and in the table below. They are what chemists loosely call "atomic weights." The continued use of the term "atomic weight" (of any element), as opposed to "relative atomic mass" has attracted considerable controversy, since at least the 1960s, mainly due to the technical difference between weight and mass in physics. [6] (see below). Both terms are officially sanctioned by IUPAC. The

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  • 4/25/2015 RelativeatomicmassWikipedia,thefreeencyclopedia

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    Theatomicnumberofhydrogenis1.Thestandardatomicweightofhydrogenis1.008(thisvalueisnotgivenhereasanexpectationinterval,asitisinelementsbelow).Atomicweightisthesameasrelativeatomicmass.Theatomicweightsofsamplesofhydrogenwillvaryaccordingtotheircontentofheavyhydrogen(deuterium),andthiswillinturndependuponwherethesamplesarecollected.

    RelativeatomicmassFromWikipedia,thefreeencyclopedia

    Relativeatomicmass(symbol:Ar)isadimensionlessphysicalquantity,theratiooftheaveragemassofatomsofanelement(fromasinglegivensampleorsource)to112ofthemassofanatomofcarbon12(knownas

    theunifiedatomicmassunit).[1][2]Therelativeatomicmassisastatisticalterm,referringtoanabundanceweightedfigureinvolvingmeasurementofmanyatoms.Asinallrelatedterms,theword"relative"referstomakingthefigurerelativetocarbon12,sothatthefinalfigureisdimensionless.

    Thetermrelativeatomicmassisexactlyequivalenttoatomicweight,whichistheolderterm.Intechnicalusage,thesevaluesaresamplespecific(i.e.,elementsourcespecific)whenanaturalelementsourceiscomposedofmorethanoneisotope.Thus,twosamplesofachemicalelementwhichisnaturallyfoundasbeingcomposedofmorethanoneisotope,collectedfromtwosubstantiallydifferentsources,areexpectedtogiveslightlydifferentrelativeatomicmasses(atomicweights),becauseisotopicconcentrationstypicallyvaryslightlyduetothehistory(origin)ofthesource.Thesevaluesdifferencesarerealandrepeatable,andcanbeusedtoidentifyspecificsamples.Forexample,asampleofelementalcarbonfromvolcanicmethanewillhaveadifferentrelativeatomicmass(atomicweight)thanonecollectedfromplantoranimaltissues(formore,seeisotopegeochemistry).Inshort,theatomicweight(relativeatomicmass)ofcarbonvariesslightlyfromplacetoplaceandfromsourcetosource,afactthatcanbeuseful.However,atypical(standard)figurealsocanbeuseful,asfollows.

    Boththetermsrelativeatomicmassandatomicweightaresometimeslooselyusedtorefertoatechnicallydifferentstandardizedexpectationvalue,calledthestandardatomicweight.Thisvalueisthemeanvalueofatomicweightsofanumberof"normalsamples"oftheelementinquestion.Forthisdefinition,"[a]normalsampleisanyreasonablypossiblesourceoftheelementoritscompoundsincommerceforindustryandscienceandhasnotbeensubjecttosignificantmodificationofisotopiccompositionwithinageologicallybriefperiod."[3]ThesestandardatomicweightsarepublishedatregularintervalsbytheCommissiononIsotopicAbundancesandAtomicWeightsoftheInternationalUnionofPureandAppliedChemistry(IUPAC)[4][5]The"standard"valuesareintendedasmeanvaluesthatcompensateforsmallvariancesintheisotopiccompositionofthechemicalelementsacrossarangeofordinarysamplesonEarth,andthustobeapplicabletonormallaboratorymaterials.However,theymaynotaccuratelyreflectvaluesfromsamplesfromunusuallocationsorextraterrestrialobjects,whichoftenhavemorewidelyvariantisotopiccompositions.

    Thestandardatomicweightsarereprintedinawidevarietyoftextbooks,commercialcatalogues,PeriodicTablewallchartsetc.,andinthetablebelow.Theyarewhatchemistslooselycall"atomicweights."

    Thecontinueduseoftheterm"atomicweight"(ofanyelement),asopposedto"relativeatomicmass"hasattractedconsiderablecontroversy,sinceatleastthe1960s,mainlyduetothetechnicaldifferencebetweenweightandmassinphysics.[6](seebelow).BothtermsareofficiallysanctionedbyIUPAC.The

  • 4/25/2015 RelativeatomicmassWikipedia,thefreeencyclopedia

    http://en.wikipedia.org/wiki/Relative_atomic_mass 2/8

    ExcerptoftheIUPACPeriodicTableoftheElementsshowingtheintervalnotationofthestandardatomicweightsofboron,carbon,andnitrogen(ChemistryInternational,IUPAC).Example:thepiechartforboronshowsittobecomposedofabout20%B10and80%B11.ThisisotopemixcausesthestandardatomicweightofordinaryEarthlyboronsamplestobeexpectedtofallwithintheinterval10.806to10.821.Boronsamplesfromunusualsources,particularlynonterrestrialsources,mighthavemeasuredatomicweightsthatfalloutsidethisrange.Atomicweightandrelativeatomicmassaresynonyms.

    term"relativeatomicmass"nowseemstobegainingasthepreferredtermover"atomicweight,"althoughinthecaseof"standardatomicweight,"thisshorterterm(asopposedto"standardrelativeatomicmass")continuestobepreferred.

    Contents

    1Definition(andcloselyrelatedterm)1.1Currentdefinition1.2Historicalamu

    2Differingtermsreferringtothemassofsingleatoms3Namingcontroversy4Determinationofrelativeatomicmass5Periodictablewithrelativeatomicmasses6Seealso7References8Externallinks

    Definition(andcloselyrelatedterm)

    Relativeatomicmass(nottobeconfusedwithrelativeisotopicmass)isasynonymforatomicweight,andinsomecircumstancesmayevenbesynonymouswithstandardatomicweight(dependingonthesample,seebelow).Itisanaverageatomicmass,ortheweightedmeanoftheatomicmassesofalltheatomsofaparticularchemicalelementfoundinaparticularsample,whichisthen

    standardizedbycomparisontocarbon12.[7]RelativeatomicmassisfrequentlyusedasasynonymforthestandardatomicweightanditiscorrecttodosoiftherelativeatomicmassusedisthatforanelementfromEarthunderdefinedconditions.However,relativeatomicmasscoversmorethan

  • 4/25/2015 RelativeatomicmassWikipedia,thefreeencyclopedia

    http://en.wikipedia.org/wiki/Relative_atomic_mass 3/8

    standardatomicweights,andisalessspecifictermthatmaymorebroadlyrefertononterrestrialenvironmentsandhighlyspecificterrestrialenvironmentsthatdeviatefromEarthaverageorhavedifferentcertainties(numberofsignificantfigures)thandothestandardatomicweights.StandardatomicweightreferstotheexpectedrelativeatomicmassoratomicweightofanelementsampleinthelocalenvironmentoftheEarth'scrustandatmosphereasdeterminedbythe

    IUPACCommissiononAtomicWeightsandIsotopicAbundances.[8]Becausethesestandardatomicweightsareanaverage(mean)ofrelativeisotopicmassesforagivenelementfromdifferentsources(placesonEarth),standardatomicweightsaresubjecttonaturalvariation.Anuncertaintyinbracketsoranexpectationintervalmaythereforebeincludedinsourcesofstandardatomicweights(seeexampleinillustrationimmediatelyabove).Thisuncertaintyreflectsnaturalvariabilityinisotopicdistributionforanelement,ratherthanuncertaintyinmeasurement(whichis

    muchsmallerwithqualityinstruments).[9]

    AlthoughthereisanattempttocovertherangeofvariabilityonEarthwithstandardatomicweightfigures,thereareknowncasesofmineralsampleswhichcontainelementswithatomicweightsthatareoutliersfromthestandardatomicweightrange.[10]

    Lithiumrepresentsauniquecasewherethenaturalabundancesoftheisotopeshaveinsomecasesbeenfoundtohavebeenperturbedbyhumanisotopicseparationactivitiestothepointofaffectingtheuncertaintyinitsstandardatomicweight,eveninsamplesobtainedfromnaturalsources,suchasrivers.

    Forsyntheticelementstheisotopeformeddependsonthemeansofsynthesis,sotheconceptofnaturalisotopeabundancehasnomeaning.Therefore,forsyntheticelementsthetotalnucleoncountofthemoststableisotope(i.e.,theisotopewiththelongesthalflife)islistedinbrackets,inplaceofthestandardatomicweight.

    Whentheterm"atomicweight"isusedinchemistry,usuallyitisthemorespecificstandardatomicweightthatisimplied.Itisstandardatomicweightsthatareusedinperiodictablesandmanystandardreferencesinordinaryterrestrialchemistry.

    Currentdefinition

    PrevailingIUPACdefinitionstakenfromthe"GoldBook"are

    atomicweightSee:relativeatomicmass[11]

    and

    relativeatomicmass(atomicweight)Theratiooftheaveragemassoftheatomtotheunified

    atomicmassunit.[12]

    Herethe"unifiedatomicmassunit"refersto1/12ofthemassofanatomof12Cinitsgroundstate.[13]

    TheIUPACdefinition[1]ofrelativeatomicmassis:

  • 4/25/2015 RelativeatomicmassWikipedia,thefreeencyclopedia

    http://en.wikipedia.org/wiki/Relative_atomic_mass 4/8

    Anatomicweight(relativeatomicmass)ofanelementfromaspecifiedsourceistheratiooftheaveragemassperatomoftheelementto1/12ofthemassofanatomof12C.

    Thedefinitiondeliberatelyspecifies"Anatomicweight",asanelementwillhavedifferentrelativeatomicmassesdependingonthesource.Forexample,boronfromTurkeyhasalowerrelativeatomicmassthanboronfromCalifornia,becauseofitsdifferentisotopiccomposition.[14][15]Nevertheless,giventhecostanddifficultyofisotopeanalysis,itisusualtousethetabulatedvaluesofstandardatomicweightswhichareubiquitousinchemicallaboratories.

    Historicalamu

    Older(pre1961)historicalrelativescales(basedontheatomicmassunit,ora.m.u.,oramu)usedeithertheoxygen16relativeisotopicmassforreference,orelsetheoxygenrelativeatomicmass(i.e.,atomicweight)forreference.Seethearticleonthehistoryofthemodernunifiedatomicmassunitfortheresolutionoftheseproblemsin1961.

    Differingtermsreferringtothemassofsingleatoms

    Relativeisotopicmassisasimilarsoundingtermwhichreferstoaquitedifferentquantity,specificallytheratioofthemassofasingleatomtothemassofaunifiedatomicmassunit,expressedasadimensionlessnumber.Therelativeisotopicmass(ofsingleatoms,etc.)isdiscussedinthearticleonatomicmass,withwhichitissynonymous,saveforchoiceofmassunits.

    Namingcontroversy

    Theuseofthename"atomicweight"hasattractedagreatdealofcontroversyamongscientists.[6]Objectorstothenameusuallyprefertheterm"relativeatomicmass"(nottobeconfusedwithatomicmass).Thebasicobjectionisthatatomicweightisnotaweight,thatistheforceexertedonanobjectinagravitationalfield,measuredinunitsofforcesuchasthenewtonorpoundal.

    Inreply,supportersoftheterm"atomicweight"pointout(amongotherarguments)[6]that

    thenamehasbeenincontinuoususeforthesamequantitysinceitwasfirstconceptualizedin

    1808[16]

    formostofthattime,atomicweightsreallyweremeasuredbyweighing(thatisbygravimetricanalysis)andthatthenameofaphysicalquantityshouldnotchangesimplybecausethemethodofitsdeterminationhaschangedtheterm"relativeatomicmass"shouldbereservedforthemassofaspecificnuclide(orisotope),while"atomicweight"beusedfortheweightedmeanoftheatomicmassesoveralltheatomsinthesampleitisnotuncommontohavemisleadingnamesofphysicalquantitieswhichareretainedforhistoricalreasons,suchas

  • 4/25/2015 RelativeatomicmassWikipedia,thefreeencyclopedia

    http://en.wikipedia.org/wiki/Relative_atomic_mass 5/8

    Isotope Atomicmass[18]Abundance[19]

    Standard Range28Si 27.97692653246(194) 92.2297(7)% 92.2192.25%29Si 28.976494700(22) 4.6832(5)% 4.674.69%30Si 29.973770171(32) 3.0872(5)% 3.083.10%

    electromotiveforce,whichisnotaforceresolvingpower,whichisnotapowerquantitymolarconcentration,whichisnotamolarquantity(aquantityexpressedperunitamountofsubstance).

    Itcouldbeaddedthatatomicweightisoftennottruly"atomic"either,asitdoesnotcorrespondtothepropertyofanyindividualatom.Thesameargumentcouldbemadeagainst"relativeatomicmass"usedinthissense.

    Determinationofrelativeatomicmass

    Modernrelativeatomicmasses(atermspecifictoagivenelementsample)arecalculatedfrommeasuredvaluesofatomicmass(foreachnuclide)andisotopiccompositionofasample.Highlyaccurateatomicmassesareavailable[17][18]forvirtuallyallnonradioactivenuclides,butisotopiccompositionsarebothhardertomeasuretohighprecisionandmoresubjecttovariationbetweensamples.[19][20]Forthisreason,therelativeatomicmassesofthe22mononuclidicelements(whicharethesameastheisotopicmassesforeachofthesinglenaturallyoccurringnuclidesoftheseelements)areknowntoespeciallyhighaccuracy.Forexample,thereisanuncertaintyofonlyonepartin38millionfortherelativeatomicmassoffluorine,aprecisionwhichisgreaterthanthecurrentbestvaluefortheAvogadroconstant(onepartin20million).

    Thecalculationisexemplifiedforsilicon,whoserelativeatomicmassisespeciallyimportantinmetrology.Siliconexistsinnatureasamixtureofthreeisotopes:28Si,29Siand30Si.Theatomicmassesofthesenuclidesareknowntoaprecisionofonepartin14billionfor28Siandaboutonepartinonebillionfortheothers.Howevertherangeofnaturalabundancefortheisotopesissuchthatthestandardabundancecanonlybegiventoabout0.001%(seetable).Thecalculationis

    Ar(Si)=(27.976930.922297)+(28.976490.046832)+(29.973770.030872)=28.0854

    Theestimationoftheuncertaintyiscomplicated,[21]especiallyasthesampledistributionisnotnecessarilysymmetrical:theIUPACstandardrelativeatomicmassesarequotedwithestimatedsymmetricaluncertainties,[22]andthevalueforsiliconis28.0855(3).Therelativestandarduncertaintyinthisvalueis1 105or10ppm.Tofurtherreflectthisnaturalvariability,in2010,IUPACmadethedecisiontolisttherelativeatomicmassesof10elementsasanintervalratherthanafixednumber.[23]

    Periodictablewithrelativeatomicmasses

  • 4/25/2015 RelativeatomicmassWikipedia,thefreeencyclopedia

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    1 2 3 4 5 6 7 8 9 10 11 12 13 14GroupPeriod

    1 H1.008

    2 Li6.94

    Be9.012

    B10.81

    C12.01 14.01

    3 Na22.99

    Mg24.31

    Al26.98

    Si28.09 30.97

    4 K39.10

    Ca40.08

    Sc44.96

    Ti47.87

    V50.94

    Cr52.00

    Mn54.94

    Fe55.85

    Co58.93

    Ni58.69

    Cu63.55

    Zn65.38

    Ga69.72

    Ge72.63

    As74.92

    5 Rb85.47

    Sr87.62

    Y88.91

    Zr91.22

    Nb92.91

    Mo95.95

    Tc[97.91]

    Ru101.07

    Rh102.91

    Pd106.42

    Ag107.87

    Cd112.41

    In114.82

    Sn118.71

    Sb121.76

    6 Cs132.91

    Ba137.33

    Hf178.49

    Ta180.95

    W183.84

    Re186.21

    Os190.23

    Ir192.22

    Pt195.08

    Au196.97

    Hg200.59

    Tl204.38

    Pb207.2 208.98

    7 Fr[223.02]

    Ra[226.03]

    Rf[267.12]

    Db[268.13]

    Sg[271.13]

    Bh[270.13]

    Hs[277.15]

    Mt[278.16]

    Ds[281.17]

    Rg[281.16]

    Cn[285.18]

    Uut[286.19]

    Fl[289.19]

    Uup[289.19]

    La138.91

    Ce140.12

    Pr140.91

    Nd144.24

    Pm[144.91]

    Sm150.36

    Eu151.96

    Gd157.25

    Tb158.93

    Dy162.50

    Ho164.93

    Er167.26

    Tm168.93

    Ac[227.03]

    Th232.04

    Pa231.04

    U238.03

    Np[237.05]

    Pu[244.06]

    Am[243.06]

    Cm[247.07]

    Bk[247.07]

    Cf[251.08]

    Es[252.08]

    Fm[257.10]

    Md[258.10]

    Primordial Fromdecay Synthetic Bordershowsnaturaloccurrenceoftheelement

    Backgroundcolorshowssubcategoryinthemetalmetalloidnonmetaltrend:Metal

    Metalloid

    Nonmetal Unknownchemicalproperties

    Alkalimetal

    Alkalineearthmetal

    Lanthanide Actinide

    Transitionmetal

    Posttransitionmetal

    Polyatomicnonmetal

    Diatomicnonmetal Noblegas

    Seealso

    InternationalUnionofPureandAppliedChemistry(IUPAC)CommissiononIsotopicAbundancesandAtomicWeights

    References

    1. InternationalUnionofPureandAppliedChemistry(1980)."AtomicWeightsoftheElements1979"(http://goldbook.iupac.org/publications/pac/1980/pdf/5210x2349.html).PureAppl.Chem.52(10):234984.doi:10.1351/pac198052102349(https://dx.doi.org/10.1351%2Fpac198052102349).

    2. InternationalUnionofPureandAppliedChemistry(1993).Quantities,UnitsandSymbolsinPhysicalChemistry,2ndedition,Oxford:BlackwellScience.ISBN0632035838.p.41.Electronicversion.(http://old.iupac.org/publications/books/gbook/green_book_2ed.pdf)

    3. Definitionofelementsample(http://goldbook.iupac.org/S05907.html)

    Atomicweight

    Legendfortheperiodictable

  • 4/25/2015 RelativeatomicmassWikipedia,thefreeencyclopedia

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    4. ThelatesteditionisInternationalUnionofPureandAppliedChemistry(2006)."AtomicWeightsoftheElements2005"(http://goldbook.iupac.org/publications/pac/2006/pdf/7811x2051.html).PureAppl.Chem.78(11):205166.doi:10.1351/pac200678112051(https://dx.doi.org/10.1351%2Fpac200678112051).

    5. Theupdatedlistofstandardatomicweightsisexpectedtobeformallypublishedinlate2008.TheIUPAC(InternationalUnionOfPureAndAppliedChemistry)CommissiononIsotopicAbundancesandAtomicWeightsannounced(http://goldbook.iupac.org/objID/Note/nt50112469625981329917907)inAugust2007thatthestandardatomicweightsofthefollowingelementswouldberevised(newfiguresquotedhere):lutetium174.9668(1)molybdenum95.96(2)nickel58.6934(4)ytterbium173.054(5)zinc65.38(2).The

    recommendedvaluefortheisotopeamountratioof40Ar/36Ar(whichcouldbeusefulasacontrolmeasurementinargonargondating)wasalsochangedfrom296.03(53)to298.56(31).

    6. deBivre,P.Peiser,H.S.(1992)." 'AtomicWeight'TheName,ItsHistory,Definition,andUnits"(http://goldbook.iupac.org/publications/pac/1992/pdf/6410x1535.html).PureAppl.Chem.64(10):153543.doi:10.1351/pac199264101535(https://dx.doi.org/10.1351%2Fpac199264101535).

    7. IUPAC,CompendiumofChemicalTerminology,2nded.(the"GoldBook")(1997).Onlinecorrectedversion:(2006)"relativeatomicmass(http://goldbook.iupac.org/R05258.html)".

    8. IUPACDefinitionofStandardAtomicWeight(http://goldbook.iupac.org/goldbook/S05907.html)9. ATOMICWEIGHTSOFTHEELEMENTS2005(IUPACTECHNICALREPORT),M.E.WIESERPure

    Appl.Chem.,V.78,pp.2051,2006(http://goldbook.iupac.org/publications/pac/2006/pdf/7811x2051.html)10. [1](http://goldbook.iupac.org/S05907.html)Definitionofstandardatomicweights:"Recommendedvaluesof

    relativeatomicmassesoftheelementsrevisedbienniallybytheIUPACCommissiononAtomicWeightsandIsotopicAbundancesandapplicabletoelementsinanynormalsamplewithahighlevelofconfidence.Anormalsampleisanyreasonablypossiblesourceoftheelementoritscompoundsincommerceforindustryandscienceandhasnotbeensubjecttosignificantmodificationofisotopiccompositionwithinageologicallybriefperiod."

    11. IUPACGoldBookatomicweight(http://goldbook.iupac.org/A00505.html)12. IUPACGoldBookrelativeatomicmass(atomicweight),Ar(http://goldbook.iupac.org/R05258.html)13. IUPACGoldBookunifiedatomicmassunit(http://goldbook.iupac.org/U06554.html)14. Greenwood,NormanN.Earnshaw,Alan(1984).ChemistryoftheElements

    (http://books.google.co.nz/books?id=OezvAAAAMAAJ&q=0080220576&dq=0080220576&source=bl&ots=m4tIRxdwSk&sig=XQTTjw5EN9n5z62JB3d0vaUEn0Y&hl=en&sa=X&ei=UoAWUN7EM6ziQfyxIDoCQ&ved=0CD8Q6AEwBA).Oxford:PergamonPress.pp.21,160.ISBN0080220576.

    15. InternationalUnionofPureandAppliedChemistry(2003)."AtomicWeightsoftheElements:Review2000"(http://goldbook.iupac.org/publications/pac/2003/pdf/7506x0683.html).PureAppl.Chem.75(6):683800.doi:10.1351/pac200375060683(https://dx.doi.org/10.1351%2Fpac200375060683).

    16. Dalton,John(1808).ANewSystemofChemicalPhilosophy(http://www.archive.org/details/newsystemofchemi01daltuoft).Manchester.

    17. NationalInstituteofStandardsandTechnology.AtomicWeightsandIsotopicCompositionsforAllElements(http://physics.nist.gov/cgibin/Compositions/stand_alone.pl?ele=&ascii=html&isotype=some).

  • 4/25/2015 RelativeatomicmassWikipedia,thefreeencyclopedia

    http://en.wikipedia.org/wiki/Relative_atomic_mass 8/8

    Externallinks

    IUPACCommissiononIsotopicAbundancesandAtomicWeights(http://www.ciaaw.org)NISTrelativeatomicmassesofallisotopesandthestandardatomicweightsoftheelements(http://physics.nist.gov/cgibin/Compositions/stand_alone.pl?ele=&ascii=html&isotype=some)AtomicWeightsoftheElements2011(http://goldbook.iupac.org/publications/pac/85/5/1047/)

    Retrievedfrom"http://en.wikipedia.org/w/index.php?title=Relative_atomic_mass&oldid=652902242"

    Categories: Amountofsubstance Chemicalproperties Stoichiometry Periodictable

    Thispagewaslastmodifiedon21March2015,at17:27.TextisavailableundertheCreativeCommonsAttributionShareAlikeLicenseadditionaltermsmayapply.Byusingthissite,youagreetotheTermsofUseandPrivacyPolicy.WikipediaisaregisteredtrademarkoftheWikimediaFoundation,Inc.,anonprofitorganization.

    18. Wapstra,A.H.Audi,G.Thibault,C.(2003),TheAME2003AtomicMassEvaluation(http://www.nndc.bnl.gov/masses/)(Onlineed.),NationalNuclearDataCenter.Basedon:

    Wapstra,A.H.Audi,G.Thibault,C.(2003),"TheAME2003atomicmassevaluation(I)",NuclearPhysicsA729:129336,Bibcode:2003NuPhA.729..129W(http://adsabs.harvard.edu/abs/2003NuPhA.729..129W),doi:10.1016/j.nuclphysa.2003.11.002(https://dx.doi.org/10.1016%2Fj.nuclphysa.2003.11.002)Audi,G.Wapstra,A.H.Thibault,C.(2003),"TheAME2003atomicmassevaluation(II)",NuclearPhysicsA729:337676,Bibcode:2003NuPhA.729..337A(http://adsabs.harvard.edu/abs/2003NuPhA.729..337A),doi:10.1016/j.nuclphysa.2003.11.003(https://dx.doi.org/10.1016%2Fj.nuclphysa.2003.11.003)

    19. Rosman,K.J.R.Taylor,P.D.P.(1998),"IsotopicCompositionsoftheElements1997"(http://media.iupac.org/publications/pac/1998/pdf/7001x0217.pdf)(PDF),PureandAppliedChemistry70(1):21735,doi:10.1351/pac199870010217(https://dx.doi.org/10.1351%2Fpac199870010217)

    20. Coplen,T.B.etal.(2002),"IsotopicAbundanceVariationsofSelectedElements"(http://www.iupac.org/publications/pac/2002/pdf/7410x1987.pdf)(PDF),PureandAppliedChemistry74(10):19872017,doi:10.1351/pac200274101987(https://dx.doi.org/10.1351%2Fpac200274101987)

    21. Meija,JurisMester,Zoltn(2008)."Uncertaintypropagationofatomicweightmeasurementresults"(http://stacks.iop.org/Met/45/53).Metrologia45:5362.Bibcode:2008Metro..45...53M(http://adsabs.harvard.edu/abs/2008Metro..45...53M).doi:10.1088/00261394/45/1/008(https://dx.doi.org/10.1088%2F00261394%2F45%2F1%2F008).

    22. Holden,NormanE.(2004)."AtomicWeightsandtheInternationalCommitteeAHistoricalReview"(http://goldbook.iupac.org/publications/ci/2004/2601/1_holden.html).ChemistryInternational26(1):47.

    23. IUPACInternationalUnionofPureandAppliedChemistry:AtomicWeightsofTenChemicalElementsAbouttoChange(http://goldbook.iupac.org/news/newsdetail/article/atomicweightsoftenchemicalelementsabouttochange.html)


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THE THEORY OF THE ATOMIC STRUCTURE · 2020. 9. 15. · Isotopes. Relative mass of atoms Isotopes have the same atomic number but different mass numbers The atomic masses that are

THE THEORY OF THE ATOMIC STRUCTURE · 2020. 9. 15. · Isotopes. Relative mass of atoms Isotopes have the same atomic number but different mass numbers The atomic masses that are

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Atomic Mass and Molecular Mass...single molecules. Thus, though the actual masses of the atoms could not be determined, their relative masses could be determined. If the atomic mass

Atomic Mass and Molecular Mass...single molecules. Thus, though the actual masses of the atoms could not be determined, their relative masses could be determined. If the atomic mass

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Z = proton number = atomic number N = neutron number A = mass number (Z+N) Atomic mass of nuclide = (rest mass – binding energy) relative to 1/12

Z = proton number = atomic number N = neutron number A = mass number (Z+N) Atomic mass of nuclide = (rest mass – binding energy) relative to 1/12

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The Basics of Chemistry · Basic Chemistry 6 D. Relative mean atomic mass. The relative atomic mass (symbol A r) is defined as a number that says how many times an atom is heavier

The Basics of Chemistry · Basic Chemistry 6 D. Relative mean atomic mass. The relative atomic mass (symbol A r) is defined as a number that says how many times an atom is heavier

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Learning Objectives: To understand what is meant by the term, relative atomic mass

Learning Objectives: To understand what is meant by the term, relative atomic mass

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Relative Atomic Mass Mass of atoms is incredibly small! So we have to use relative atomic mass. The symbol for relative atomic mass is Ar Carbon- 12 atom

Relative Atomic Mass Mass of atoms is incredibly small! So we have to use relative atomic mass. The symbol for relative atomic mass is Ar Carbon- 12 atom

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Relative Atomic Mass & Isotopes 5.1. Until recently it was impossible to weigh individual atoms

Relative Atomic Mass & Isotopes 5.1. Until recently it was impossible to weigh individual atoms

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Chemistry and Life. The Periodic Table Atomic Number: Number of Protons and Electrons Atomic mass: Mass relative to Carbon-12

Chemistry and Life. The Periodic Table Atomic Number: Number of Protons and Electrons Atomic mass: Mass relative to Carbon-12

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Atomic Number, Mass Number, Atomic Mass and Isotopes

Atomic Number, Mass Number, Atomic Mass and Isotopes

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Chapter 7 – The Mole and Chemical Composition Sec 2 - Relative Atomic Mass and Chemical Formulas

Chapter 7 – The Mole and Chemical Composition Sec 2 - Relative Atomic Mass and Chemical Formulas

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Unit F321 Module 1.2.1 Electron Structure. Atomic Structure Protons, neutrons, electrons How to make ions Relative atomic mass

Unit F321 Module 1.2.1 Electron Structure. Atomic Structure Protons, neutrons, electrons How to make ions Relative atomic mass

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Chapter 3: Chemical Formulae and Equations 3.1 Relative Atomic Mass and Relative Molecular Mass

Chapter 3: Chemical Formulae and Equations 3.1 Relative Atomic Mass and Relative Molecular Mass

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Relative Atomic Mass and the Mole Chapter 4 of Hienemann Textbook

Relative Atomic Mass and the Mole Chapter 4 of Hienemann Textbook

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Chemistry: Atomic Structure & The Periodic Table Checklist · Chemistry: Atomic Structure & The Periodic Table Checklist . Can you ... 1.1.6 Relative atomic mass ... To access the

Chemistry: Atomic Structure & The Periodic Table Checklist · Chemistry: Atomic Structure & The Periodic Table Checklist . Can you ... 1.1.6 Relative atomic mass ... To access the

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IB Chemistry on Atomic Structure, Particle Physics and Relative Atomic Mass

IB Chemistry on Atomic Structure, Particle Physics and Relative Atomic Mass

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Atomic Structure - Dr. G's Chemistrydrgchemistry.weebly.com/.../atomic_structure_.pdf · Finding Relative Atomic Mass • Find the relative atomic mass of Rubidium if 77% of the sample

Atomic Structure - Dr. G's Chemistrydrgchemistry.weebly.com/.../atomic_structure_.pdf · Finding Relative Atomic Mass • Find the relative atomic mass of Rubidium if 77% of the sample

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Lots of definitions to learn Isotopes Isotopes The Mole The Mole Avogadro number Avogadro number Relative Atomic/Molecular Mass Relative Atomic/Molecular

Lots of definitions to learn Isotopes Isotopes The Mole The Mole Avogadro number Avogadro number Relative Atomic/Molecular Mass Relative Atomic/Molecular

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ATOMIC MASS & AVERAGE ATOMIC MASS

ATOMIC MASS & AVERAGE ATOMIC MASS

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Author: J R Reid The Mole Mass Relative Atomic Mass Amount Calculations

Author: J R Reid The Mole Mass Relative Atomic Mass Amount Calculations

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Separating substances with the same relative atomic mass · Separating substances with the same relative atomic mass. Separating two molecules with a quadrupole o High Stability Power

Separating substances with the same relative atomic mass · Separating substances with the same relative atomic mass. Separating two molecules with a quadrupole o High Stability Power

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F4 Chapter 3 Relative Atomic Mass

F4 Chapter 3 Relative Atomic Mass

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Atomic Structure. Relative masses/charges of protons, neutrons and electrons Sub-atomic particle Relative Mass Relative Charge Proton (p)1+1 Neutron

Atomic Structure. Relative masses/charges of protons, neutrons and electrons Sub-atomic particle Relative Mass Relative Charge Proton (p)1+1 Neutron

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METALLIC COBALT PARTICLES (WITH OR WITHOUT TUNGSTEN … · 1.1.2 Molecular formulae and relative molecular mass Co Relative atomic mass: 58.93 CoSO 4.7H 2 O Relative molecular mass:

METALLIC COBALT PARTICLES (WITH OR WITHOUT TUNGSTEN … · 1.1.2 Molecular formulae and relative molecular mass Co Relative atomic mass: 58.93 CoSO 4.7H 2 O Relative molecular mass:

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shakeribchem.weebly.com · Web viewmasses of atoms are compared on a scale relative to 12C and are expressed as relative atomic mass (A r) and relative formula/molecular mass (M r)

shakeribchem.weebly.com · Web viewmasses of atoms are compared on a scale relative to 12C and are expressed as relative atomic mass (A r) and relative formula/molecular mass (M r)

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1 of 7© Boardworks Ltd 2009. 2 of 7© Boardworks Ltd 2009 Relative atomic mass The relative atomic mass (A r ) of an element is the mass of one of its

1 of 7© Boardworks Ltd 2009. 2 of 7© Boardworks Ltd 2009 Relative atomic mass The relative atomic mass (A r ) of an element is the mass of one of its

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