Symbol (chemistry)

See also: Hazard symbol

In chemistry, a symbol is a code for a chemical element. It is usually derived from the modern name of the element but for some elements it is derived from the name in Latin.[nb 1] For example, "He" is the symbol for helium (English name, not known in ancient Roman times), "Pb" for lead (plumbum in Latin), "Hg" for mercury (hydrargyrum in Greek), "W" for tungsten (wolfram in German, not known in Roman times). Only the first letter is capitalized.

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 no longer officially used.

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

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

In Chinese, each chemical element has a dedicated character, usually created for the purpose (see Chemical elements in East Asian languages). However, Latin symbols are also used, especially in formulas.

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.

Symbols

Symbol Name Etymology of symbol Atomic number Relative atomic mass Group Period Metallic
character
AcActiniumGreek aktinos (ray)89[227][nb 2]  7 Actinide
AgSilverLatin argentum (silver)47107.8682(2)[nb 3]115 Transition metal
AlAluminium (aluminum) Latin alumen (alum)1326.9815386(8)133 Post-transition metal
AmAmericiumthe Americas95[243][nb 2] 7 Actinide
ArArgonGreek argon (inert)1839.948(1)[nb 3][nb 4]183 Noble gas
AsArsenicGreek arsenikos (male)3374.92160(2)154 Metalloid
AtAstatineGreek astatos (unstable)85[210][nb 2]176 Metalloid
AuGoldLatin aurum (gold)79196.966569(4)116 Transition metal
BBoronborax510.811(7)[nb 3][nb 4][nb 5]132 Metalloid
BaBariumGreek barys (density)56137.327(7)26 Alkaline earth metal
BeBerylliumberyl49.012182(3)22 Alkaline earth metal
BhBohriumNiels Bohr107[264][nb 2]77 Transition metal
BiBismuth German wiss muth (white-mass), becoming bismuth in English83208.98040(1)156 Post-transition metal
BkBerkeliumBerkeley, California97[247][nb 2] 7 Actinide
BrBromineGreek bromos (stench)3579.904(1)174 Diatomic nonmetal
CCarbonLatin carbo (charcoal)612.0107(8)[nb 3][nb 4]142 Polyatomic nonmetal
CaCalciumLatin calx (lime)2040.078(4)[nb 3]24 Alkaline earth metal
CdCadmiumGreek kadmia (earth)48112.411(8)[nb 3]125 Transition metal
CeCeriumCeres58140.116(1)[nb 3] 6 Lanthanide
CfCaliforniumState and University of California98[251][nb 2] 7 Actinide
ClChlorineGreek chloros (green-yellow)1735.453(2)[nb 3][nb 4][nb 5]173 Diatomic nonmetal
CmCuriumPierre and Marie Curie and the traditional -um ending96[247][nb 2] 7 Actinide
CnCoperniciumNicolaus Copernicus 112[285][nb 2]127 Transition metal
CoCobaltGerman kobold2758.933195(5)94 Transition metal
CrChromiumGreek chroma (color)2451.9961(6)64 Transition metal
CsCaesium (cesium)Latin caesius (sky blue)55132.9054519(2)16 Alkali metal
CuCopperLatin Cuprum (Cyprus)2963.546(3)[nb 4]114 Transition metal
DbDubniumDubna, Russia105[262][nb 2]57 Transition metal
DsDarmstadtiumDarmstadt, Germany110[271][nb 2]107 Unknown
DyDysprosiumGreek dysprositos66162.500(1)[nb 3] 6 Lanthanide
ErErbiumYtterby, Sweden68167.259(3)[nb 3] 6 Lanthanide
EsEinsteiniumAlbert Einstein99[252][nb 2] 7 Actinide
EuEuropiumEurope63151.964(1)[nb 3] 6 Lanthanide
FFluorineLatin fluo (flow)918.9984032(5)172 Diatomic nonmetal
FeIronLatin ferrum (iron)2655.845(2)84 Transition metal
FlFleroviumFlerov Laboratory of Nuclear Reactions114[289][nb 2]147 Unknown
FmFermiumEnrico Fermi100[257][nb 2] 7 Actinide
FrFranciumFrance87[223][nb 2]17 Alkali metal
GaGalliumLatin Gallia (Gaul)3169.723(1)134 Post-transition metal
GdGadoliniumgadolinite64157.25(3)[nb 3] 6 Lanthanide
GeGermaniumGermany3272.64(1)144 Metalloid
HHydrogenGreek hydor gennao (liquid-produce)11.00794(7)[nb 3][nb 4][nb 5]11 Diatomic nonmetal
HeHeliumGreek helios (Sun)24.002602(2)[nb 3][nb 4]181 Noble gas
HfHafniumLatin Hafnia (Copenhagen)72178.49(2)46 Transition metal
HgMercuryGreek hydrargyrum (liquid silver)80200.59(2)126 Transition metal
HoHolmiumLatin Holmia (Stockholm)67164.930 32(2) 6 Lanthanide
HsHassiumHesse, Germany108[277][nb 2]87 Transition metal
IIodineGreek ioeides (violet)53126.904 47(3)175 Diatomic nonmetal
InIndiumindigo blue49114.818(3)135 Post-transition metal
IrIridiumGreek iris (rainbow)77192.217(3)96 Transition metal
KPotassiumLatin kalium (potassium)1939.0983(1)14 Alkali metal
KrKryptonGreek kryptos (concealment)3683.798(2)[nb 3][nb 5]184 Noble gas
LaLanthanumGreek lanthano (escape)57138.90547(7)[nb 3] 6 Lanthanide
LiLithiumGreek lithos (rock)36.941(2)[nb 3][nb 4][nb 5][nb 6]12 Alkali metal
LrLawrenciumErnest O. Lawrence103[262][nb 2]37 Actinide
LuLutetiumLatin Lutetia (Paris)71174.967(1)[nb 3]36 Lanthanide
LvLivermoriumLawrence Livermore National Laboratory116[292][nb 2]167 Unknown
MdMendeleviumDmitri Mendeleyev101[258][nb 2] 7 Actinide
MgMagnesiumMagnesia, Greece1224.3050(6)23 Alkaline earth metal
MnManganeseGreek magnes (magnet)2554.938045(5)74 Transition metal
MoMolybdenumGreek molybdos (lead)4295.94(2)[nb 3]65 Transition metal
MtMeitneriumLise Meitner109[268][nb 2]97 Unknown
NNitrogenGreek nitron (niter)714.0067(2)[nb 3][nb 4]152 Diatomic nonmetal
NaSodiumLatin natrium (sodium)1122.98976928(2)13 Alkali metal
NbNiobiumNiobe4192.906 38(2)55 Transition metal
NdNeodymiumGreek neos didymos (novelty-twin)60144.242(3)[nb 3] 6 Lanthanide
NeNeonGreek neos (novelty)1020.1797(6)[nb 3][nb 5]182 Noble gas
NiNickelGerman kupfernickel (nickeline)2858.6934(2)104 Transition metal
NoNobeliumAlfred Nobel102[259][nb 2] 7 Actinide
NpNeptuniumNeptune93[237][nb 2] 7 Actinide
OOxygenGreek oxys (acid)815.9994(3)[nb 3][nb 4]162 Diatomic nonmetal
OsOsmiumGreek osme (odor)76190.23(3)[nb 3]86 Transition metal
PPhosphorusGreek phosphoros (light bearer)1530.973762(2)153 Polyatomic nonmetal
PaProtactiniumGreek protos and actinium91231.03588(2)[nb 2] 7 Actinide
PbLeadLatin plumbum (lead)82207.2(1)[nb 3][nb 4]146 Post-transition metal
PdPalladiumPallas (genitive Pallados)46106.42(1)[nb 3]105 Transition metal
PmPromethiumPrometheus61[145][nb 2] 6 Lanthanide
PoPoloniumPoland84[210][nb 2]166 Post-transition metal
PrPraseodymiumGreek prasios (green)59140.90765(2) 6 Lanthanide
PtPlatinumSpanish platina (silver)78195.084(9)106 Transition metal
PuPlutoniumPluto94[244][nb 2] 7 Actinide
RaRadiumLatin radius (ray)88[226][nb 2]27 Alkaline earth metal
RbRubidiumLatin rubidus (red)3785.4678(3)[nb 3]15 Alkali metal
ReRheniumGerman Rheinprovinz75186.207(1)76 Transition metal
RfRutherfordiumErnest Rutherford104261[nb 2]47 Transition metal
RgRoentgeniumWilhelm Conrad Röntgen111[272][nb 2]117 Unknown
RhRhodiumGreek rhodon (rose)45102.905 50(2)95 Transition metal
RnRadonradium and emanation86[220][nb 2]186 Noble gas
RuRutheniumLatin Ruthenia (Russia)44101.07(2)[nb 3]85 Transition metal
SSulfur (Sulphur)Latin sulfur1632.065(5)[nb 3][nb 4]163 Polyatomic nonmetal
SbAntimonyLatin stibium (eye liner)51121.760(1)[nb 3]155 Metalloid
ScScandiumScandinavia2144.955912(6)34 Transition metal
SeSeleniumGreek selene (Moon)3478.96(3)[nb 4]164 Polyatomic nonmetal
SgSeaborgiumGlenn T. Seaborg106[266][nb 2]67 Transition metal
SiSiliconLatin silex (flint)1428.0855(3)[nb 4]143 Metalloid
SmSamariumsamarskite62150.36(2)[nb 3] 6 Lanthanide
SnTinLatin stannum (tin)50118.710(7)[nb 3]145 Post-transition metal
SrStrontiumStrontian3887.62(1)[nb 3][nb 4]25 Alkaline earth metal
TaTantalumKing Tantalus73180.94788(2)56 Transition metal
TbTerbiumYtterby, Sweden65158.92535(2) 6 Lanthanide
TcTechnetiumGreek technetos (artificial)43[98][nb 2]75 Transition metal
TeTelluriumGreek tellus (Earth)52127.60(3)[nb 3]165 Metalloid
ThThoriumThor90232.03806(2)[nb 2][nb 3] 7 Actinide
TiTitaniumthe Titans2247.867(1)44 Transition metal
TlThalliumGreek thallos (shoot)81204.3833(2)136 Post-transition metal
TmThuliumThule and the traditional -ium ending69168.93421(2) 6 Lanthanide
UUraniumUranus92238.02891(3)[nb 2][nb 3][nb 5] 7 Actinide
UuoUnunoctiumLatin uni, uni, and oct (one, one, eight)118[294][nb 2]187 Unknown
UupUnunpentiumLatin uni, uni, and Greek pent (one, one, five)115[288][nb 2]157 Unknown
UusUnunseptiumLatin uni, uni, and sept (one, one, seven)117[294][nb 2]177 Unknown
UutUnuntriumLatin uni, uni, and Greek tri (one, one, three)113[284][nb 2]137 Unknown
VVanadiumVanadis2350.9415(1)54 Transition metal
WTungstenGerman wolfram (wolf-froth)74183.84(1)66 Transition metal
XeXenonGreek xenos (alien)54131.293(6)[nb 3][nb 5]185 Noble gas
YYttriumYtterby, Sweden3988.90585(2)35 Transition metal
YbYtterbiumYtterby, Sweden70173.04(3)[nb 3] 6 Lanthanide
ZnZincGerman zin (tin)3065.409(4)124 Transition metal
ZrZirconiumzircon4091.224(2)[nb 3]45 Transition metal
Legend for category color
Background color shows subcategory in the metal–metalloid–nonmetal trend:
Metal Metalloid Nonmetal Unknown
chemical
properties
Alkali metal Alkaline earth metal Lan­thanide Actinide Transition metal Post-transition metal Polyatomic nonmetal Diatomic nonmetal Noble 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

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 7]
AbAlabamine85Discredited claim to discovery of astatine. [nb 8]
AdAldebaranium70Former name of ytterbium. [nb 8]
AmAlabamium85Discredited claim to discovery of astatine. The symbol is now used for americium[nb 8]
AnAthenium99Proposed name for einsteinium. [nb 9]
AoAusonium93Discredited claim to discovery of neptunium. [nb 8]
AzAzote7Former name for nitrogen. [nb 7]
BoBoron5Current symbol is B. [nb 7]
BvBrevium91Former name for protactinium. [nb 7]
BzBerzelium59Suggested name for praseodymium. [nb 9]
CbColumbium41Former name of niobium. [nb 7]
CbColumbium95Suggested name for americium. [nb 9]
ChChromium24Current symbol is Cr. [nb 7]
ClColumbium41Former name of niobium. The symbol is now used for chlorine. [nb 7]
CpCassiopeium71Former name for lutetium. [nb 7]
CpCopernicium112Current symbol is Cn. [nb 7]
CtCenturium100Proposed name for fermium. [nb 9]
CtCeltium72Former name of hafnium. [nb 7]
DaDanubium43Suggested name for technetium. [nb 9]
DbDubnium104Proposed name for rutherfordium. The symbol and name were used for element 105. [nb 7][nb 9]
DiDidymium Mixture of the elements praseodymium and neodymium. Mosander wrongly believed didymium to be an element[2]
EEinsteinium99Current symbol is Es. [nb 7]
EaEkaaluminium31Name given by Mendeleev to an as of then undiscovered element. When discovered, gallium closely matched the prediction. [nb 9][nb 10]
EbEkaboron21Name given by Mendeleev to an as of then undiscovered element. When discovered, scandium closely matched the prediction. [nb 9][nb 10]
ElEkaaluminium31Name given by Mendeleev to an as of then undiscovered element. When discovered, gallium closely matched the prediction. [nb 9][nb 10]
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 7]
EmEkamanganese43Name given by Mendeleev to an as of then undiscovered element. When discovered, technetium closely matched the prediction. [nb 9][nb 10]
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 9][nb 10]
EsEsperium94Discredited claim to discovery of plutonium. The symbol is now used for einsteinium. [nb 8]
FaFrancium87Current symbol is Fr. [nb 7]
FlFluorine9Current symbol is F. The symbol is now used for flerovium.[nb 7]
FlFlorentium61Discredited claim to discovery of promethium. The symbol is now used for flerovium. [nb 8]
FrFlorentium61Discredited claim to discovery of promethium. The symbol is now used for francium. [nb 8]
GGlucinium4Former name of beryllium. [nb 7]
GlGlucinium4Former name of beryllium. [nb 7]
HaHahnium105Proposed name for dubnium. [nb 9]
HnHahnium108Proposed name for hassium. [nb 9]
HyMercury80Current symbol is Hg. [nb 7]
IIridium77Current symbol is Ir. The symbol is now used for iodine. [nb 7]
IlIllinium61Discredited claim to discovery of promethium. [nb 8]
JJodium53Former name of iodine. [nb 7]
JgJargonium72Discredited claim to discovery of hafnium. [nb 8]
JlJoliotium105Proposed name for dubnium. [nb 9]
KuKurchatovium104Proposed name for rutherfordium. [nb 9]
LwLawrencium103Current symbol is Lr. [nb 7]
MMuriaticum17Former name of chlorine. [nb 7]
MaManganese25Current symbol is Mn. [nb 7]
MaMasurium43Disputed claim to discovery of technetium. [nb 8]
MdMendelevium97Proposed name for berkelium. The symbol and name were later used for element 101. [nb 7][nb 9]
MeMendelevium68Suggested name for erbium. [nb 7]
MlMoldavium87Suggested name for francium. [nb 9]
MsMagnesium12Current symbol is Mg. [nb 7]
MsMasrium49Discredited claim of discovery of indium. [nb 8]
MtMeitnium91Suggested name for protactinium. The symbol is now used for meitnerium. [nb 9]
MvMendelevium101Current symbol is Md. [nb 7]
NgNorwegium72Discredited claim to discovery of hafnium. [nb 8]
NoNorium72Discredited claim to discovery of hafnium. The symbol is now used for nobelium. [nb 8]
NsNielsbohrium105Proposed name for dubnium. [nb 9]
NsNielsbohrium107Proposed name for bohrium. [nb 9]
NtNiton86Former name for radon. [nb 7]
NyNeoytterbium70Former name of ytterbium. [nb 7]
OdOdinium62Suggested name for samarium. [nb 9]
PLead82Current symbol is Pb. The symbol is now used for phosphorus. [nb 7]
PaPalladium46Current symbol is Pd. The symbol is now used for protactinium. [nb 7]
PePelopium41Former name for niobium. [nb 7]
PlPalladium46Current symbol is Pd. [nb 7]
PoPotassium19Current symbol is K. The letters were later used for polonium. [nb 7]
RRhodium45Current symbol is Rh. [nb 7]
RfRutherfordium106Proposed name for seaborgium. The symbol and name were instead used for element 104. [nb 7][nb 9]
RoRhodium45Current symbol is Rh. [nb 7]
SaSamarium62Current symbol is Sm. [nb 7]
SoSodium11Current symbol is Na. [nb 7]
SpSpectrium70Suggested name for ytterbium. [nb 9]
StTin50Current symbol is Sn. [nb 7]
StAntimony51Current symbol is Sb. [nb 7]
TnTungsten74Current symbol is W. [nb 7]
TuThulium69Current symbol is Tm. [nb 7]
TuTungsten74Current symbol is W. [nb 7]
TyTyrium60Suggested name for neodymium. [nb 9]
UnbUnnilbium102Temporary name given to nobelium until it was permanently named by IUPAC. [nb 10]
UneUnnilennium109Temporary name given to meitnerium until it was permanently named by IUPAC. [nb 10]
UnhUnnilhexium106Temporary name given to seaborgium until it was permanently named by IUPAC. [nb 10]
UnoUnniloctium108Temporary name given to hassium until it was permanently named by IUPAC. [nb 10]
UnpUnnilpentium105Temporary name given to dubnium until it was permanently named by IUPAC. [nb 10]
UnqUnnilquadium104Temporary name given to rutherfordium until it was permanently named by IUPAC. [nb 10]
UnsUnnilseptium107Temporary name given to bohrium until it was permanently named by IUPAC. [nb 10]
UntUnniltrium103Temporary name given to lawrencium until it was permanently named by IUPAC. [nb 10]
UnuUnnilunium101Temporary name given to mendelevium until it was permanently named by IUPAC. [nb 10]
UubUnunbium112Temporary name given to copernicium until it was permanently named by IUPAC. [nb 10]
UuhUnunhexium116Temporary name given to livermorium until it was permanently named by IUPAC. [nb 10]
UunUnunnilium110Temporary name given to darmstadtium until it was permanently named by IUPAC. [nb 10]
UuqUnunquadium114Temporary name given to flerovium until it was permanently named by IUPAC. [nb 10]
UuuUnununium111Temporary name given to roentgenium until it was permanently named by IUPAC. [nb 10]
UrUranium92Current symbol is U. [nb 7]
ViVirginium87Discredited claim to discovery of francium. [nb 8]
VmVirginium87Discredited claim to discovery of francium. [nb 8]
YtYttrium39Current symbol is Y. [nb 7]

Pictographic symbols

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 Chinese characters for elements. Modern alphabetic notation was introduced in 1814 by Jöns Jakob Berzelius.

Chemical symbolOriginal nameModern nameAtomic numberOrigin of symbol
HydrogenHydrogen1Daltonian symbol circa 1808.
SulfurSulfur16Alchemical symbol.
PallasSulfur16Alchemical symbol.
🜍SulfurSulfur16Alchemical symbol.
SulfurSulfur16Daltonian symbol circa 1808.
MagnesiumMagnesium12Alchemical symbol.
MarsIron26Alchemical symbol.
Stellae FixaeCopper29Pre–16th-century alchemical symbol.
VenusCopper29Alchemical symbol.
CopperCopper29Alchemical symbol.
©CopperCopper29Daltonian symbol circa 1808.
ArsenicArsenic33Alchemical symbol.
🜺ArsenicArsenic33Alchemical symbol.
LunaSilver47Alchemical symbol.
🜛SilverSilver47Alchemical symbol.
IupiterTin50Alchemical symbol.
AntimonyAntimony51Alchemical symbol.
AntimonyAntimony51Alchemical symbol.
PlatinumPlatinum78Alchemical symbol.
PlatinumPlatinum78Alchemical symbol.
UranusPlatinum78Alchemical symbol.
SolGold79Alchemical symbol from the 16th century.
SolGold79Alchemical symbol from 1700 through 1783.
🜚GoldGold79Alchemical symbol.
PiscesMercury80Pre–16th-century alchemical symbol.
NeptunusMercury80Alchemical symbol from the 17th century.
MercuriusMercury80Alchemical symbol from 1700 through 1783.
SaturnusLead82Alchemical symbol circa 1783.
TaurusBismuth83Alchemical symbol.

Symbols for named isotopes

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. The symbols for the named isotopes of hydrogen, deuterium (D) and tritium (T) are still in use today. Heavy water and other deuterated solvents are commonly used in chemistry, and it is convenient to use a single character rather than a symbol with a subscript in these cases. The practice also continues with tritium compounds. When the name of the solvent is given, a lowercase d is sometimes used. For example, d6-benzene and C6D6 can be used instead of [2H6]C6H6.[3]

The symbols for isotopes of elements other than hydrogen are no longer in use within the scientific community. 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.[4]

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

General:

From organic chemistry:

From inorganic chemistry:

See also

Notes

  1. This should not be confused with formula. When a number is present at the bottom right corner of the symbol of the element, only then is it said to be a formula, but if the number is not present, it is a symbol.
  2. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 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.
  3. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 The isotopic composition of this element varies in some geological specimens, and the variation may exceed the uncertainty stated in the table.
  4. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 The isotopic composition varies in terrestrial material such that a more precise atomic weight can not be given.
  5. 1 2 3 4 5 6 7 8 The isotopic composition of the element can vary in commercial materials, which can cause the atomic weight to deviate significantly from the given value.
  6. 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.
  7. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 Name changed due to a standardization of, modernization of, or update to older formerly-used symbol.
  8. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Name designated by discredited/disputed claimant.
  9. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Name proposed prior to discovery/creation of element or prior to official re-naming of a placeholder name.
  10. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Temporary placeholder name.

References

  1. The interstellar medium, with definition of HI and HII regions
  2. Praseodymium
  3. IUPAC. "Isotopically Modified Compounds". IUPAC. Retrieved 31 March 2015.
  4. Morgan, G.T., ed. (1905). "Annual Reports on the Progress of Chemistry for 1904". Journal of the Chemical Society (Gurney & Jackson) 1: 268. In view of the extraordinarily complex nature of the later changes occurring in Radium, Rutherford has proposed a new and convenient system of nomenclature. The first product of the change of the radium emanation is named radium A, the next radium B, and so on.

External links

This article is issued from Wikipedia - version of the Saturday, February 13, 2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.