Symbol (chemistry)

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A chemical symbol is a 1-, 2-, or 3-letter internationally agreed code for a chemical element, usually derived from the name of the element, often in Latin.

This is an example of an atomic symbol. The text boxes explain where the numbers are derived from.

Only the first letter is capitalized. For example, "He" is the symbol for helium (English name, not known in ancient Roman times), "Pb" for lead (plumbum in Latin), "W" for tungsten (wolfram in German, not known in Roman times). Temporary symbols assigned to newly or not-yet synthesized elements use 3-letter symbols based on their atomic numbers. For example, "Uno" was the temporary symbol for hassium which had the temporary name of unniloctium and "Uuo" is the symbol for ununoctium (temporary name) with the atomic mass 118.

Chemical symbols may be modified by the use of prepended superscripts or subscripts to specify a particular isotope of an atom. Additionally, appended superscripts may be used to indicate the ionization or oxidation state of an element. They are widely used in chemistry and they have been officially chosen by the International Union of Pure and Applied Chemistry. There are also some historical symbols that are currently not official any more.

Attached subscripts or superscripts specifying a nucleotide or molecule have the following meanings and positions:

In Chinese each chemical element has an ideograph, usually created for the purpose, as its symbol (see Chemical elements in East Asian languages).

The Periodic Table, elements being denoted by their symbols

A list of current, dated, as well as proposed and historical signs and symbols is included here with its signification. Also given is each element's atomic number, atomic weight or the atomic mass of the most stable isotope, group and period numbers on the periodic table, and etymology of the symbol.

Current symbols[edit]

SymbolNameEtymology of symbolAtomic numberRelative atomic massGroupPeriodMetallic
character
AcActiniumfrom Greek aktinos (ray)89&227[227][nb 1] 7Actinide
AgSilverLatin argentum (silver)47&107.86822107.8682(2)[nb 2]115Transition metal
AlAluminium (Aluminum)Latin alumen (alum)13&026.9815386826.9815386(8)133Poor metal
AmAmericiumthe Americas95&243[243][nb 1] 7Actinide
ArArgonGreek argon (inert)18&039.948139.948(1)[nb 2][nb 3]183Noble gas
AsArsenicGreek arsenikos (male)33&074.92160274.92160(2)154Metalloid
AtAstatineGreek astatos (unstable)85&210[210][nb 1]176Metalloid
AuGoldLatin aurum (gold)79&196.9665694196.966569(4)116Transition metal
BBoronborax5&010.811710.811(7)[nb 2][nb 3][nb 4]132Metalloid
BaBariumGreek barys (density)56&137.3277137.327(7)26Alkaline earth metal
BeBerylliumberyl4&009.01218239.012182(3)22Alkaline earth metal
BhBohriumNiels Bohr107&264[264][nb 1]77Transition metal
BiBismuthfrom German wiss muth (white-mass), becoming bismuth in English83&208.980401208.98040(1)156Poor metal
BkBerkeliumBerkeley, California97&247[247][nb 1] 7Actinide
BrBromineGreek bromos (stench)35&079.904179.904(1)174Diatomic nonmetal
CCarbonLatin carbo (charcoal)6&012.0107812.0107(8)[nb 2][nb 3]142Polyatomic nonmetal
CaCalciumLatin calx (lime)20&040.078440.078(4)[nb 2]24Alkaline earth metal
CdCadmiumGreek kadmia (earth)48&112.4118112.411(8)[nb 2]125Transition metal
CeCeriumCeres58&140.1161140.116(1)[nb 2] 6Lanthanide
CfCaliforniumState and University of California98&251[251][nb 1] 7Actinide
ClChlorineGreek chloros (green-yellow)17&035.453235.453(2)[nb 2][nb 3][nb 4]173Diatomic nonmetal
CmCuriumPierre and Marie Curie and the traditional -um ending96&247[247][nb 1] 7Actinide
CnCoperniciumNicolaus Copernicus112&285[285][nb 1]127Transition metal
CoCobaltfrom German kobold27&058.933195558.933195(5)94Transition metal
CrChromiumGreek chroma (color)24&051.9961651.9961(6)64Transition metal
CsCaesium (Cesium)Latin caesius (sky blue)55&132.90545192132.9054519(2)16Alkali metal
CuCopperLatin Cuprum (Cyprus)29&063.546363.546(3)[nb 3]114Transition metal
DbDubniumDubna, Russia105&262[262][nb 1]57Transition metal
DsDarmstadtiumDarmstadt, Germany110&271[271][nb 1]107Unknown
DyDysprosiumGreek dysprositos66&162.5001162.500(1)[nb 2] 6Lanthanide
ErErbiumYtterby, Sweden68&167.2593167.259(3)[nb 2] 6Lanthanide
EsEinsteiniumAlbert Einstein99&252[252][nb 1] 7Actinide
EuEuropiumEurope63&151.9641151.964(1)[nb 2] 6Lanthanide
FFluorineLatin fluo (flow)9&018.9984032518.9984032(5)172Diatomic nonmetal
FeIronLatin ferrum (iron)26&055.845255.845(2)84Transition metal
FlFleroviumFlerov Laboratory of Nuclear Reactions114&289[289][nb 1]147Unknown
FmFermiumEnrico Fermi100&257[257][nb 1] 7Actinide
FrFranciumFrance87&223[223][nb 1]17Alkali metal
GaGalliumLatin Gallia (Gaul)31&069.723169.723(1)134Poor metal
GdGadoliniumgadolinite64&157.253157.25(3)[nb 2] 6Lanthanide
GeGermaniumGermany32&072.64172.64(1)144Metalloid
HHydrogenGreek hydor gennao (liquid-produce)1&001.0079471.00794(7)[nb 2][nb 3][nb 4]11Diatomic nonmetal
HeHeliumGreek helios (Sun)2&004.00260224.002602(2)[nb 2][nb 3]181Noble gas
HfHafniumLatin Hafnia (Copenhagen)72&178.492178.49(2)46Transition metal
HgMercuryGreek hydrargyrum (liquid silver)80&200.592200.59(2)126Transition metal
HoHolmiumLatin Holmia (Stockholm)67&164.930322164.930 32(2) 6Lanthanide
HsHassiumHesse, Germany108&277[277][nb 1]87Transition metal
IIodineGreek ioeides (violet)53&126.904473126.904 47(3)175Diatomic nonmetal
InIndiumindigo blue49&114.8183114.818(3)135Poor metal
IrIridiumGreek iris (rainbow)77&192.2173192.217(3)96Transition metal
KPotassiumLatin kalium (potassium)19&039.0983139.0983(1)14Alkali metal
KrKryptonGreek kryptos (concealment)36&083.798283.798(2)[nb 2][nb 4]184Noble gas
LaLanthanumGreek lanthano (escape)57&138.905477138.90547(7)[nb 2] 6Lanthanide
LiLithiumGreek lithos (rock)3&006.94126.941(2)[nb 2][nb 3][nb 4][nb 5]12Alkali metal
LrLawrenciumErnest O. Lawrence103&262[262][nb 1]37Actinide
LuLutetiumLatin Lutetia (Paris)71&174.9671174.967(1)[nb 2]36Lanthanide
LvLivermoriumLawrence Livermore National Laboratory116&292[292][nb 1]167Unknown
MdMendeleviumDmitri Mendeleyev101&258[258][nb 1] 7Actinide
MgMagnesiumMagnesia, Greece12&024.3050624.3050(6)23Alkaline earth metal
MnManganeseGreek magnes (magnet)25&054.938045554.938045(5)74Transition metal
MoMolybdenumGreek molybdos (lead)42&095.94295.94(2)[nb 2]65Transition metal
MtMeitneriumLise Meitner109&268[268][nb 1]97Unknown
NNitrogenGreek nitron (niter)7&014.0067214.0067(2)[nb 2][nb 3]152Diatomic nonmetal
NaSodiumLatin natrium (sodium)11&022.98976928222.98976928(2)13Alkali metal
NbNiobiumNiobe41&092.90638292.906 38(2)55Transition metal
NdNeodymiumGreek neos didymos (novelty-twin)60&144.2423144.242(3)[nb 2] 6Lanthanide
NeNeonGreek neos (novelty)10&020.1797620.1797(6)[nb 2][nb 4]182Noble gas
NiNickelGerman kupfernickel (nickeline)28&058.6934258.6934(2)104Transition metal
NoNobeliumAlfred Nobel102&259[259][nb 1] 7Actinide
NpNeptuniumNeptune93&237[237][nb 1] 7Actinide
OOxygenGreek oxys (acid)8&015.9994315.9994(3)[nb 2][nb 3]162Diatomic nonmetal
OsOsmiumGreek osme (odor)76&190.233190.23(3)[nb 2]86Transition metal
PPhosphorusGreek phosphoros (light bearer)15&030.973762230.973762(2)153Polyatomic nonmetal
PaProtactiniumGreek protos and actinium91&231.035882231.03588(2)[nb 1] 7Actinide
PbLeadLatin plumbum (lead)82&207.21207.2(1)[nb 2][nb 3]146Poor metal
PdPalladiumPallas (genitive Pallados)46&106.421106.42(1)[nb 2]105Transition metal
PmPromethiumPrometheus61&145[145][nb 1] 6Lanthanide
PoPoloniumPoland84&210[210][nb 1]166Poor metal
PrPraseodymiumGreek prasios (green)59&140.907652140.90765(2) 6Lanthanide
PtPlatinumSpanish platina (silver)78&195.0849195.084(9)106Transition metal
PuPlutoniumPluto94&244[244][nb 1] 7Actinide
RaRadiumLatin radius (ray)88&226[226][nb 1]27Alkaline earth metal
RbRubidiumLatin rubidus (red)37&085.4678385.4678(3)[nb 2]15Alkali metal
ReRheniumGerman Rheinprovinz75&186.2071186.207(1)76Transition metal
RfRutherfordiumErnest Rutherford104&261261[nb 1]47Transition metal
RgRoentgeniumWilhelm Conrad Röntgen111&272[272][nb 1]117Unknown
RhRhodiumGreek rhodon (rose)45&102.905502102.905 50(2)95Transition metal
RnRadonradium and emanation86&220[220][nb 1]186Noble gas
RuRutheniumLatin Ruthenia (Russia)44&101.072101.07(2)[nb 2]85Transition metal
SSulfur (Sulphur)Latin sulfur16&032.065532.065(5)[nb 2][nb 3]163Polyatomic nonmetal
SbAntimonyLatin stibium (eye liner)51&121.7601121.760(1)[nb 2]155Metalloid
ScScandiumScandinavia21&044.955912644.955912(6)34Transition metal
SeSeleniumGreek selene (Moon)34&078.96378.96(3)[nb 3]164Polyatomic nonmetal
SgSeaborgiumGlenn T. Seaborg106&266[266][nb 1]67Transition metal
SiSiliconLatin silex (flint)14&028.0855328.0855(3)[nb 3]143Metalloid
SmSamariumsamarskite62&150.362150.36(2)[nb 2] 6Lanthanide
SnTinLatin stannum (tin)50&118.7101118.710(7)[nb 2]145Poor metal
SrStrontiumStrontian38&087.62187.62(1)[nb 2][nb 3]25Alkaline earth metal
TaTantalumKing Tantalus73&180.947882180.94788(2)56Transition metal
TbTerbiumYtterby, Sweden65&158.925352158.92535(2) 6Lanthanide
TcTechnetiumGreek technetos (artificial)43&098[98][nb 1]75Transition metal
TeTelluriumGreek tellus (Earth)52&127.603127.60(3)[nb 2]165Metalloid
ThThoriumThor90&232.038062232.03806(2)[nb 1][nb 2] 7Actinide
TiTitaniumthe Titans22&047.867147.867(1)44Transition metal
TlThalliumGreek thallos (shoot)81&204.38332204.3833(2)136Poor metal
TmThuliumThule and the traditional -ium ending69&168.934212168.93421(2) 6Lanthanide
UUraniumUranus92&238.028913238.02891(3)[nb 1][nb 2][nb 4] 7Actinide
UuoUnunoctiumLatin uni, uni, and oct (one, one, eight)118&294[294][nb 1]187Unknown
UupUnunpentiumLatin uni, uni, and Greek pent (one, one, five)115&288[288][nb 1]157Unknown
UusUnunseptiumLatin uni, uni, and sept (one, one, seven)117&294[294][nb 1]177Unknown
UutUnuntriumLatin uni, uni, and Greek tri (one, one, three)113&284[284][nb 1]137Unknown
VVanadiumVanadis23&050.9415150.9415(1)54Transition metal
WTungstenGerman wolfram (wolf-froth)74&183.841183.84(1)66Transition metal
XeXenonGreek xenos (alien)54&131.2936131.293(6)[nb 2][nb 4]185Noble gas
YYttriumYtterby, Sweden39&088.90585288.90585(2)35Transition metal
YbYtterbiumYtterby, Sweden70&173.043173.04(3)[nb 2] 6Lanthanide
ZnZincGerman zin (tin)30&065.409465.409(4)124Transition metal
ZrZirconiumzircon40&091.224291.224(2)[nb 2]45Transition metal
Legend for category color
Background color shows subcategory in the metal–nonmetal range:
MetalMetalloidNonmetalUnknown
chemical
properties
Alkali metalAlkaline earth metalLan­thanideActinideTransition metalPoor metalPolyatomic nonmetalDiatomic nonmetalNoble gas

Antimatter atoms are denoted by a bar above the symbol for their matter counterpart, so e.g. H is the symbol for antihydrogen.

Symbols not currently used[edit]

The following is a list of symbols formerly used or suggested for elements, including symbols for placeholder names and names given by discredited claimants for discovery.

Chemical symbolNameAtomic numberOrigin of symbolWhy not used
AArgon18Current symbol is Ar.[nb 6]
AbAlabamine85Discredited claim to discovery of astatine.[nb 7]
AdAldebaranium70Former name of ytterbium.[nb 7]
AmAlabamium85Discredited claim to discovery of astatine. The symbol is now used for americium[nb 7]
AnAthenium99Proposed name for einsteinium.[nb 8]
AoAusonium93Discredited claim to discovery of neptunium.[nb 7]
AzAzote7Former name for nitrogen.[nb 6]
BoBoron5Current symbol is B.[nb 6]
BvBrevium91Former name for protactinium.[nb 6]
BzBerzelium59Suggested name for praseodymium.[nb 8]
CbColumbium41Former name of niobium.[nb 6]
CbColumbium95Suggested name for americium.[nb 8]
ChChromium24Current symbol is Cr.[nb 6]
ClColumbium41Former name of niobium. The symbol is now used for chlorine.[nb 6]
CpCassiopeium71Former name for lutetium.[nb 6]
CtCenturium100Proposed name for fermium.[nb 8]
CtCeltium72Former name of hafnium.[nb 6]
DaDanubium43Suggested name for technetium.[nb 8]
DbDubnium104Proposed name for rutherfordium. The symbol and name were used for element 105.[nb 6][nb 8]
EEinsteinium99Current symbol is Es.[nb 6]
EaEkaaluminium31Name given by Mendeleev to an as of then undiscovered element. When discovered, gallium closely matched the prediction.[nb 8][nb 9]
EbEkaboron21Name given by Mendeleev to an as of then undiscovered element. When discovered, scandium closely matched the prediction.[nb 8][nb 9]
ElEkaaluminium31Name given by Mendeleev to an as of then undiscovered element. When discovered, gallium closely matched the prediction.[nb 8][nb 9]
EmEmanation86Also called radium emanation, the name was originally given by Friedrich Ernst Dorn in 1900. In 1923, this element officially became radon (the name given at one time to 222Rn, an isotope identified in the decay chain of radium).[nb 6]
EmEkamanganese43Name given by Mendeleev to an as of then undiscovered element. When discovered, technetium closely matched the prediction.[nb 8][nb 9]
EsEkasilicon32Name given by Mendeleev to an as of then undiscovered element. When discovered, germanium closely matched the prediction. The symbol is now used for einsteinium.[nb 8][nb 9]
EsEsperium94Discredited claim to discovery of plutonium. The symbol is now used for einsteinium.[nb 7]
FaFrancium87Current symbol is Fr.[nb 6]
FlFluorine9Current symbol is F. The letters are now used for flerovium.[nb 6]
FlFlorentium61Discredited claim to discovery of promethium. The symbol is now used for flerovium.[nb 7]
FrFlorentium61Discredited claim to discovery of promethium. The symbol is now used for francium.[nb 7]
GGlucinium4Former name of beryllium.[nb 6]
GlGlucinium4Former name of beryllium.[nb 6]
HaHahnium105Proposed name for dubnium.[nb 8]
HnHahnium108Proposed name for hassium.[nb 8]
HyMercury80Current symbol is Hg.[nb 6]
IIridium77Current symbol is Ir. The symbol is now used for iodine.[nb 6]
IlIllinium61Discredited claim to discovery of promethium.[nb 7]
JJodium53Old name of iodine.[nb 6]
JgJargonium72Discredited claim to discovery of hafnium.[nb 7]
JlJoliotium105Proposed name for dubnium.[nb 8]
KuKurchatovium104Proposed name for rutherfordium.[nb 8]
LwLawrencium103Current symbol is Lr.[nb 6]
MMuriaticum17Former name of chlorine.[nb 6]
MaManganese25Current symbol is Mn.[nb 6]
MaMasurium43Disputed claim to discovery of technetium.[nb 7]
MdMendelevium97Proposed name for berkelium. The symbol and name were later used for element 101.[nb 6][nb 8]
MeMendelevium68Suggested name for erbium.[nb 6]
MlMoldavium87Suggested name for francium.[nb 8]
MsMagnesium12Current symbol is Mg.[nb 6]
MsMasrium49Discredited claim of discovery of indium.[nb 7]
MtMeitnium91Suggested name for protactinium. The symbol is now used for meitnerium.[nb 8]
MvMendelevium101Current symbol is Md.[nb 6]
NgNorwegium72Discredited claim to discovery of hafnium.[nb 7]
NoNorium72Discredited claim to discovery of hafnium.[nb 7]
NsNielsbohrium105Proposed name for dubnium.[nb 8]
NsNielsbohrium107Proposed name for bohrium.[nb 8]
NtNiton86Former name for radon.[nb 6]
NyNeoytterbium70Former name of ytterbium.[nb 6]
OdOdinium62Suggested name for samarium.[nb 8]
PLead82Current symbol is Pb. The symbol is now used for phosphorus.[nb 6]
PaPalladium46Current symbol is Pd. The symbol is now used for protactinium.[nb 6]
PePelopium41Former name for niobium.[nb 6]
PlPalladium46Current symbol is Pd.[nb 6]
PoPotassium19Current symbol is K. The letters were later used for polonium.[nb 6]
RRhodium45Current symbol is Rh.[nb 6]
RfRutherfordium106Proposed name for seaborgium. The symbol and name were instead used for element 104.[nb 6][nb 8]
RoRhodium45Current symbol is Rh.[nb 6]
SaSamarium62Current symbol is Sm.[nb 6]
SoSodium11Current symbol is Na.[nb 6]
SpSpectrium70Suggested name for ytterbium.[nb 8]
StTin50Current symbol is Sn.[nb 6]
StAntimony51Current symbol is Sb.[nb 6]
TnTungsten74Current symbol is W.[nb 6]
TuThulium69Current symbol is Tm.[nb 6]
TuTungsten74Current symbol is W.[nb 6]
TyTyrium60Suggested name for neodymium.[nb 8]
UnbUnnilbium102Temporary name given to nobelium until it was permanently named by IUPAC.[nb 9]
UneUnnilennium109Temporary name given to meitnerium until it was permanently named by IUPAC.[nb 9]
UnhUnnilhexium106Temporary name given to seaborgium until it was permanently named by IUPAC.[nb 9]
UnoUnniloctium108Temporary name given to hassium until it was permanently named by IUPAC.[nb 9]
UnpUnnilpentium105Temporary name given to dubnium until it was permanently named by IUPAC.[nb 9]
UnqUnnilquadium104Temporary name given to rutherfordium until it was permanently named by IUPAC.[nb 9]
UnsUnnilseptium107Temporary name given to bohrium until it was permanently named by IUPAC.[nb 9]
UntUnniltrium103Temporary name given to lawrencium until it was permanently named by IUPAC.[nb 9]
UnuUnnilunium101Temporary name given to mendelevium until it was permanently named by IUPAC.[nb 9]
UubUnunbium112Temporary name given to copernicium until it was permanently named by IUPAC.[nb 9]
UuhUnunhexium116Temporary name given to livermorium until it was permanently named by IUPAC.[nb 9]
UunUnunnilium110Temporary name given to darmstadtium until it was permanently named by IUPAC.[nb 9]
UuqUnunquadium114Temporary name given to flerovium until it was permanently named by IUPAC.[nb 9]
UuuUnununium111Temporary name given to roentgenium until it was permanently named by IUPAC.[nb 9]
UrUranium92Current symbol is U.[nb 6]
ViVirginium87Discredited claim to discovery of francium.[nb 7]
VmVirginium87Discredited claim to discovery of francium.[nb 7]
YtYttrium39Current symbol is Y.[nb 6]

Pictographic symbols[edit]

The following is a list of pictographic symbols employed to symbolize elements known since ancient times (for example to the alchemists). Not included in this list are symbolic representations of substances previously called elements (such as certain rare earth mineral blends and the classical elements fire and water of ancient philosophy) which are known today to be multi-atomic. Also not included are symbolic representations currently used for elements in other languages such as the Traditional Chinese elements. Modern alphabetic notation was introduced in 1814 by Jöns Jakob Berzelius.

Chemical symbolOriginal nameModern nameAtomic numberOrigin of symbol
Sun symbol.svgHydrogenHydrogen1Daltonian symbol circa 1808.
Sulfur symbol 1.pngSulfurSulfur16Alchemical symbol.
Sulfur symbol 2.pngPallasSulfur16Alchemical symbol.
Earth symbol.svgSulfurSulfur16Daltonian symbol circa 1808.
MagnesiumMagnesium12Alchemical symbol.
MarsIron26Alchemical symbol.
Marian star four-tenths.svgStellae FixaeCopper29Pre-16th century alchemical symbol.
VenusCopper29Alchemical symbol.
Copper symbol.svgCopperCopper29Alchemical symbol.
©CopperCopper29Daltonian symbol circa 1808.
Arsenic alchemical symbol.svgArsenicArsenic33Alchemical symbol.
Crescent.svgLunaSilver47Alchemical symbol.
Jupiter symbol.svgIupiterTin50Alchemical symbol.
AntimonyAntimony51Alchemical symbol.
Antimony-symbol.pngAntimonyAntimony51Alchemical symbol.
PlatinumPlatinum78Alchemical symbol.
PlatinumPlatinum78Alchemical symbol.
Uranus symbol.svgUranusPlatinum78Alchemical symbol.
SolGold79Alchemical symbol from the 16th century.
Sun symbol.svgSolGold79Alchemical symbol from 1700 through 1783.
Pisces.svgPiscesMercury80Pre-16th century alchemical symbol.
Neptune symbol.svgNeptunusMercury80Alchemical symbol from the 17th century.
Mercury symbol.svgMercuriusMercury80Alchemical symbol from 1700 through 1783.
Saturn symbol.svgSaturnusLead82Alchemical symbol circa 1783.
Bismuth symbol.pngTaurusBismuth83Alchemical symbol.

Symbols for named isotopes[edit]

The following is a list of isotopes of elements given in the previous tables which have been designated unique symbols. By this it is meant that a comprehensive list of current systematic symbols (in the uAtom form) are not included in the list and can instead be found in the Isotope index chart. Some of the following symbols are no longer in use within the scientific community, however others (most notably some of the named isotopes of hydrogen) continue to be used today. Many of these symbols were designated during the early years of radiochemistry, and several isotopes (namely those in the actinium decay family, the radium decay family, and the thorium decay family) bear placeholder names using the early naming system devised by Ernest Rutherford.

Chemical symbolNameAtomic numberOrigin of symbol
AcActinium89From the Greek aktinos. Name restricted at one time to 227Ac, an isotope of actinium. This named isotope later became the official name for element 89.
AcAActinium A84From actinium and A. Placeholder name given at one time to 215Po, an isotope of polonium identified in the decay chain of actinium.
AcBActinium B82From actinium and B. Placeholder name given at one time to 211Pb, an isotope of lead identified in the decay chain of actinium.
AcCActinium C83From actinium and C. Placeholder name given at one time to 211Bi, an isotope of bismuth identified in the decay chain of actinium.
AcC'Actinium C'84From actinium and C'. Placeholder name given at one time to 211Po, an isotope of polonium identified in the decay chain of actinium.
AcC"Actinium C"81From actinium and C". Placeholder name given at one time to 207Tl, an isotope of thallium identified in the decay chain of actinium.
AcKActinium K87Name given at one time to 223Fr, an isotope of francium identified in the decay chain of actinium.
AcUActino-uranium92Name given at one time to 235U, an isotope of uranium.
AcXActinium X88Name given at one time to 223Ra, an isotope of radium identified in the decay chain of actinium.
AnActinon86From actinium and emanation. Name given at one time to 219Rn, an isotope of radon identified in the decay chain of actinium.
DDeuterium1From the Greek deuteros. Name given to 2H.
IoIonium90Name given at one time to 230Th, an isotope of thorium identified in the decay chain of uranium.
MsTh1Mesothorium 188Name given at one time to 228Ra, an isotope of radium.
MsTh2Mesothorium 289Name given at one time to 228Ac, an isotope of actinium.
PaProtactinium91From the Greek protos and actinium. Name restricted at one time to 231Pa, an isotope of protactinium. This named isotope later became the official name for element 91.
RaRadium88From the Latin radius. Name restricted at one time to 226Ra, an isotope of radium. This named isotope later became the official name for element 88.
RaARadium A84From radium and A. Placeholder name given at one time to 218Po, an isotope of polonium identified in the decay chain of radium.
RaBRadium B82From radium and B. Placeholder name given at one time to 214Pb, an isotope of lead identified in the decay chain of radium.
RaCRadium C83From radium and C. Placeholder name given at one time to 214Bi, an isotope of bismuth identified in the decay chain of radium.
RaC'Radium C'84From radium and C'. Placeholder name given at one time to 214Po, an isotope of polonium identified in the decay chain of radium.
RaC"Radium C"81From radium and C". Placeholder name given at one time to 210Tl, an isotope of thallium identified in the decay chain of radium.
RaDRadium D82From radium and D. Placeholder name given at one time to 210Pb, an isotope of lead identified in the decay chain of radium.
RaERadium E83From radium and E. Placeholder name given at one time to 210Bi, an isotope of bismuth identified in the decay chain of radium.
RaE"Radium E"81From radium and E". Placeholder name given at one time to 206Tl, an isotope of thallium identified in the decay chain of radium.
RaFRadium F84From radium and F. Placeholder name given at one time to 210Po, an isotope of polonium identified in the decay chain of radium.
RdAcRadioactinium90Name given at one time to 227Th, an isotope of thorium.
RdThRadiothorium90Name given at one time to 228Th, an isotope of thorium.
RnRadon86From radium and emanation. Name restricted at one time to 222Rn, an isotope of radon identified in the decay chain of radium. This named isotope later became the official name for element 86 in 1923.
TTritium1From the Greek tritos. Name given to 3H.
ThThorium90After Thor. Name restricted at one time to 232Th, an isotope of thorium. This named isotope later became the official name for element 90.
ThAThorium A84From thorium and A. Placeholder name given at one time to 216Po, an isotope of polonium identified in the decay chain of thorium.
ThBThorium B82From thorium and B. Placeholder name given at one time to 212Pb, an isotope of lead identified in the decay chain of thorium.
ThCThorium C83From thorium and C. Placeholder name given at one time to 212Bi, an isotope of bismuth identified in the decay chain of thorium.
ThC'Thorium C'84From thorium and C'. Placeholder name given at one time to 212Po, an isotope of polonium identified in the decay chain of thorium.
ThC"Thorium C"81From thorium and C". Placeholder name given at one time to 208Tl, an isotope of thallium identified in the decay chain of thorium.
ThXThorium X88Name given at one time to 224Ra, an isotope of radium identified in the decay chain of thorium.
TnThoron86From thorium and emanation. Name given at one time to 220Rn, an isotope of radon identified in the decay chain of thorium.
UIUranium I92Name given at one time to 238U, an isotope of uranium.
UIIUranium II92Name given at one time to 234U, an isotope of uranium.
UX1Uranium X190Name given at one time to 234Th, an isotope of thorium identified in the decay chain of uranium.
UX2Uranium X291Name given at one time to 234Pa, an isotope of protactinium identified in the decay chain of uranium.
UYUranium Y90Name given at one time to 231Th, an isotope of thorium identified in the decay chain of uranium.
UZUranium Z91Name given at one time to 234Pa, an isotope of protactinium identified in the decay chain of uranium.

Other symbols that look like element symbols[edit]

General:

From organic chemistry:

From inorganic chemistry:

See also[edit]

Notes[edit]

  1. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak The element does not have any stable nuclides, and a value in brackets, e.g. [209], indicates the mass number of the longest-lived isotope of the element. However, three elements, thorium, protactinium, and uranium, have a characteristic terrestrial isotopic composition, and thus their atomic mass given.
  2. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am The isotopic composition of this element varies in some geological specimens, and the variation may exceed the uncertainty stated in the table.
  3. ^ a b c d e f g h i j k l m n o The isotopic composition varies in terrestrial material such that a more precise atomic weight can not be given.
  4. ^ a b c d e f g h The isotopic composition of the element can vary in commercial materials, which can cause the atomic weight to deviate significantly from the given value.
  5. ^ The atomic weight of commercial Lithium can vary between 6.939 and 6.996—analysis of the specific material is necessary to find a more accurate value.
  6. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq ar as Name changed due to a standardization of, modernization of, or update to older formerly-used symbol.
  7. ^ a b c d e f g h i j k l m n o Name designated by discredited/disputed claimant.
  8. ^ a b c d e f g h i j k l m n o p q r s t u v w x Name proposed prior to discovery/creation of element or prior to official re-naming of a placeholder name.
  9. ^ a b c d e f g h i j k l m n o p q r s Temporary placeholder name.

References[edit]

External links[edit]