සංකේතය (රසායනික මූලද්‍රව්‍යය)

රසායනික මූලද්‍රව්‍යවල සංකේත යනු රසායනික මූලද්‍රව්‍යය කෙටි කර දැක්වීම සදහා භාවිතා කරන කෙටි යෙදුම් වේ.සාමාන්‍යයෙන් මේවා ඉංග්‍රිසි අකුරු එකකින් හෝ දෙකකින් සමන්විත වේ. අකුරු දෙකක් ඇතිවිට පලමු අකුර කැපිටල් අකුරක් වන අතර දෙවන අකුර සිම්පල් අකුරකි. එක් අකුරක් නම් එය කැපිටල් අකුරකි. තාවකාලික නම් සදහා අකුරු 3ක් ඇත.මෙම සංකේත විශාල ලෙස භාවිතා වන්නේ රසායන විද්‍යාවේදි වන අතර මෙම නාමකරණය අන්තර්ජාතික ශුද්ධ හා ව්‍යවහාරික රසායන විද්‍යා සංගමය මගින් සිදුකරයි International Union of Pure and Applied Chemistry. සමහරක් පැරණි සංකේත තවදුරටත් භාවිතා නොකරන අවස්ථාද පවතී.

පවත්නා සංකේත
{|class="wikitable sortable" border="2" cellpadding="1" cellspacing="0" style="margin:1em 1em 1em 0; background:#f9f9f9; border:1px #aaa solid; border-collapse:collapse;"
|-bgcolor="#efefef"
!width="75"|සංකේතය
!width="150"|නම
!width="150" class="unsortable"|සංකේතයෙහි නිරුක්තිය
!width="75"|පරමාණුක ක්‍රමාංකය
!width="110"|සාපේක්ෂ පරමාණුක ස්කන්ධය
!width="50"|කාණ්ඩය
!width="50"|ආවර්තය
|-style="background-color:#ff99cc"
|Ac||Actinium||from Greek aktinos||89||&227[227]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.|| ||7
|-style="background-color:#ffc0c0"
|Ag||Silver||Latin argentum||47||&107.86822107.8682(2)The isotopic composition of this element varies in some geological specimens, and the variation may exceed the uncertainty stated in the table.||11||5
|-style="background-color:#cccccc"
|Al||Aluminium (Aluminum)||Latin alumen||13||&026.9815386826.9815386(8)||13||3
|-style="background-color:#ff99cc"
|Am||Americium||the Americas||95||&243[243]|| ||7
|-style="background-color:#c0ffff"
|Ar||Argon||Greek argon||18||&039.948139.948(1)The isotopic composition varies in terrestrial material such that a more precise atomic weight can not be given.||18||3|}</onlyinclude>
|-style="background-color:#cccc99"
|As||Arsenic||Greek arsenikos||33||&074.92160274.92160(2)||15||4
|-style="background-color:#ffff99"
|At||Astatine||Greek astatos||85||&210[210]||17||6
|-style="background-color:#ffc0c0"
|Au||Gold||Latin aurum||79||&196.9665694196.966569(4)||11||6
|-style="background-color:#cccc99"
|B||Boron||borax||5||&010.811710.811(7)The isotopic composition of the element can vary in commercial materials, which can cause the atomic weight to deviate significantly from the given value.||13||2
|-style="background-color:#ffdead"
|Ba||Barium||Greek barys||56||&137.3277137.327(7)||2||6
|-style="background-color:#ffdead"
|Be||Beryllium||beryl||4||&009.01218239.012182(3)||2||2
|-style="background-color:#ffc0c0"
|Bh||Bohrium||Niels Bohr||107||&264[264]||7||7
|-style="background-color:#cccccc"
|Bi||Bismuth|| from German wissmuth, becoming bismuth in English||83||&208.980401208.98040(1)||15||6
|-style="background-color:#ff99cc"
|Bk||Berkelium||Berkeley, California||97||&247[247]|| ||7
|-style="background-color:#ffff99"
|Br||Bromine||Greek bromos||35||&079.904179.904(1)||17||4
|-style="background-color:#a0ffa0"
|C||Carbon||Latin carbo||6||&012.0107812.0107(8)||14||2
|-style="background-color:#ffdead"
|Ca||කැල්සියම්||Latin calx||20||&040.078440.078(4)||2||4
|-style="background-color:#ffc0c0"
|Cd||Cadmium||from Greek kadmia||48||&112.4118112.411(8)||12||5
|-style="background-color:#ffbfff"
|Ce||Cerium||Ceres||58||&140.1161140.116(1)|| ||6
|-style="background-color:#ff99cc"
|Cf||Californium||State and University of California||98||&251[251]|| ||7
|-style="background-color:#ffff99"
|Cl||Chlorine||Greek chloros||17||&035.453235.453(2)||17||3
|-style="background-color:#ff99cc"
|Cm||Curium||Pierre and Marie Curie and the traditional -um ending||96||&247[247]|| ||7
|-style="background-color:#ffc0c0"
|Cn||Copernicium||Nicolaus Copernicus ||112||&285[285]||12||7
|-style="background-color:#ffc0c0"
|Co||Cobalt||from German kobold||27||&058.933195558.933195(5)||9||4
|-style="background-color:#ffc0c0"
|Cr||Chromium||Greek chroma||24||&051.9961651.9961(6)||6||4
|-style="background-color:#ff6666"
|Cs||Caesium (Cesium)||Latin caesius||55||&132.90545192132.9054519(2)||1||6
|-style="background-color:#ffc0c0"
|Cu||තඹ||Latin Cuprum||29||&063.546363.546(3)||11||4
|-style="background-color:#ffc0c0"
|Db||Dubnium||Dubna, රුසියාව||105||&262[262]||5||7
|-style="background-color:#e8e8e8"
|Ds||Darmstadtium||Darmstadt, ජර්මනිය||110||&271[271]||10||7
|-style="background-color:#ffbfff"
|Dy||Dysprosium||Greek dysprositos||66||&162.5001162.500(1)|| ||6
|-style="background-color:#ffbfff"
|Er||Erbium||Ytterby, Sweden||68||&167.2593167.259(3)|| ||6
|-style="background-color:#ff99cc"
|Es||Einsteinium||Albert Einstein||99||&252[252]|| ||7
|-style="background-color:#ffbfff"
|Eu||Europium||Europe||63||&151.9641151.964(1)|| ||6
|-style="background-color:#ffff99"
|F||Fluorine||Latin fluo||9||&018.9984032518.9984032(5)||17||2
|-style="background-color:#ffc0c0"
|Fe||Iron||Latin ferrum||26||&055.845255.845(2)||8||4
|-style="background-color:#ff99cc"
|Fm||Fermium||Enrico Fermi||100||&257[257]|| ||7
|-style="background-color:#ff6666"
|Fr||Francium||France||87||&223[223]||1||7
|-style="background-color:#cccccc"
|Ga||Gallium||Latin Gallia||31||&069.723169.723(1)||13||4
|-style="background-color:#ffbfff"
|Gd||Gadolinium||gadolinite||64||&157.253157.25(3)|| ||6
|-style="background-color:#cccc99"
|Ge||Germanium||Germany||32||&072.64172.64(1)||14||4
|-style="background-color:#a0ffa0"
|H||Hydrogen||Greek [[water forming|hydrogenes]]||1||&001.0079471.00794(7)||1||1
|-style="background-color:#c0ffff"
|He||Helium||Greek helios||2||&004.00260224.002602(2)||18||1
|-style="background-color:#ffc0c0"
|Hf||Hafnium||Latin Hafnia||72||&178.492178.49(2)||4||6
|-style="background-color:#ffc0c0"
|Hg||Mercury||Latin hydrargyrum||80||&200.592200.59(2)||12||6
|-style="background-color:#ffbfff"
|Ho||Holmium||Latin Holmia||67||&164.930322164.930 32(2)|| ||6
|-style="background-color:#ffc0c0"
|Hs||Hassium||Hesse, ජර්මනිය||108||&277[277]||8||7
|-style="background-color:#ffff99"
|I||Iodine||Greek ioeides||53||&126.904473126.904 47(3)||17||5
|-style="background-color:#cccccc"
|In||Indium||indigo blue||49||&114.8183114.818(3)||13||5
|-style="background-color:#ffc0c0"
|Ir||Iridium||Greek iris||77||&192.2173192.217(3)||9||6
|-style="background-color:#ff6666"
|K||Potassium (Kalium)||Latin kalium||19||&039.0983139.0983(1)||1||4
|-style="background-color:#c0ffff"
|Kr||Krypton||Greek kryptos||36||&083.798283.798(2)||18||4
|-style="background-color:#ffbfff"
|La||Lanthanum||Greek lanthanien||57||&138.905477138.90547(7)|| ||6
|-style="background-color:#ff6666"
|Li||Lithium||Greek lithos||3||&006.94126.941(2)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.||1||2
|-style="background-color:#ff99cc"
|Lr||Lawrencium||Ernest O. Lawrence||103||&262[262]||3||7
|-style="background-color:#ffbfff"
|Lu||Lutetium||Latin Lutetia||71||&174.9671174.967(1)||3||6
|-style="background-color:#ff99cc"
|Md||Mendelevium||Dmitri Mendeleyev||101||&258[258]|| ||7
|-style="background-color:#ffdead"
|Mg||Magnesium||Magnesia, Greece||12||&024.3050624.3050(6)||2||3
|-style="background-color:#ffc0c0"
|Mn||Manganese||Latin magnes||25||&054.938045554.938045(5)||7||4
|-style="background-color:#ffc0c0"
|Mo||Molybdenum||Greek molybdos||42||&095.94295.94(2)||6||5
|-style="background-color:#e8e8e8"
|Mt||Meitnerium||Lise Meitner||109||&268[268]||9||7
|-style="background-color:#a0ffa0"
|N||Nitrogen||Greek nitron||7||&014.0067214.0067(2)||15||2
|-style="background-color:#ff6666"
|Na||සෝඩියම්||Latin natrium||11||&022.98976928222.98976928(2)||1||3
|-style="background-color:#ffc0c0"
|Nb||Niobium||Niobe||41||&092.90638292.906 38(2)||5||5
|-style="background-color:#ffbfff"
|Nd||Neodymium||Greek neos didymos||60||&144.2423144.242(3)|| ||6
|-style="background-color:#c0ffff"
|Ne||Neon||Greek neos||10||&020.1797620.1797(6)||18||2
|-style="background-color:#ffc0c0"
|Ni||Nickel||German kupfernickel||28||&058.6934258.6934(2)||10||4
|-style="background-color:#ff99cc"
|No||Nobelium||Alfred Nobel||102||&259[259]|| ||7
|-style="background-color:#ff99cc"
|Np||Neptunium||Neptune||93||&237[237]|| ||7
|-style="background-color:#a0ffa0"
|O||Oxygen||Greek oxys||8||&015.9994315.9994(3)||16||2
|-style="background-color:#ffc0c0"
|Os||Osmium||Greek osme||76||&190.233190.23(3)||8||6
|-style="background-color:#a0ffa0"
|P||Phosphorus||Greek phosphoros||15||&030.973762230.973762(2)||15||3
|-style="background-color:#ff99cc"
|Pa||Protactinium||Greek protos and actinium||91||&231.035882231.03588(2)|| ||7
|-style="background-color:#cccccc"
|Pb||Lead||Latin plumbum||82||&207.21207.2(1)||14||6
|-style="background-color:#ffc0c0"
|Pd||Palladium||Pallas (genitive Pallados)||46||&106.421106.42(1)||10||5
|-style="background-color:#ffbfff"
|Pm||Promethium||Prometheus||61||&145[145]|| ||6
|-style="background-color:#cccc99"
|Po||Polonium||Poland||84||&210[210]||16||6
|-style="background-color:#ffbfff"
|Pr||Praseodymium||Greek prasios||59||&140.907652140.90765(2)|| ||6
|-style="background-color:#ffc0c0"
|Pt||Platinum||Greek platina||78||&195.0849195.084(9)||10||6
|-style="background-color:#ff99cc"
|Pu||Plutonium||Pluto||94||&244[244]|| ||7
|-style="background-color:#ffdead"
|Ra||Radium||Latin radius||88||&226[226]||2||7
|-style="background-color:#ff6666"
|Rb||Rubidium||Latin rubidus||37||&085.4678385.4678(3)||1||5
|-style="background-color:#ffc0c0"
|Re||Rhenium||German Rheinprovinz||75||&186.2071186.207(1)||7||6
|-style="background-color:#ffc0c0"
|Rf||Rutherfordium||Ernest Rutherford||104||&261261||4||7
|-style="background-color:#e8e8e8"
|Rg||Roentgenium||Wilhelm Conrad Röntgen||111||&272[272]||11||7
|-style="background-color:#ffc0c0"
|Rh||Rhodium||Greek rhodon||45||&102.905502102.905 50(2)||9||5
|-style="background-color:#c0ffff"
|Rn||Radon||radium and emanation||86||&220[220]||18||6
|-style="background-color:#ffc0c0"
|Ru||Ruthenium||Latin Ruthenia||44||&101.072101.07(2)||8||5
|-style="background-color:#a0ffa0"
|S||Sulfur (Sulphur)||Latin sulfur||16||&032.065532.065(5)||16||3
|-style="background-color:#cccc99"
|Sb||Antimony||Latin stibium||51||&121.7601121.760(1)||15||5
|-style="background-color:#ffc0c0"
|Sc||Scandium||Scandinavia||21||&044.955912644.955912(6)||3||4
|-style="background-color:#a0ffa0"
|Se||Selenium||Greek selene||34||&078.96378.96(3)||16||4
|-style="background-color:#ffc0c0"
|Sg||Seaborgium||Glenn T. Seaborg||106||&266[266]||6||7
|-style="background-color:#cccc99"
|Si||Silicon||Latin silex||14||&028.0855328.0855(3)||14||3
|-style="background-color:#ffbfff"
|Sm||Samarium||samarskite||62||&150.362150.36(2)|| ||6
|-style="background-color:#cccccc"
|Sn||Tin||Latin stannum||50||&118.7101118.710(7)||14||5
|-style="background-color:#ffdead"
|Sr||Strontium||Gaelic Strontian||38||&087.62187.62(1)||2||5
|-style="background-color:#ffc0c0"
|Ta||Tantalum||King Tantalus||73||&180.947882180.94788(2)||5||6
|-style="background-color:#ffbfff"
|Tb||Terbium||Ytterby, Sweden||65||&158.925352158.92535(2)|| ||6
|-style="background-color:#ffc0c0"
|Tc||Technetium||Greek technetos||43||&098[98]||7||5
|-style="background-color:#cccc99"
|Te||Tellurium||Greek tellus||52||&127.603127.60(3)||16||5
|-style="background-color:#ff99cc"
|Th||Thorium||Thor||90||&232.038062232.03806(2)|| ||7
|-style="background-color:#ffc0c0"
|Ti||Titanium||the Titans||22||&047.867147.867(1)||4||4
|-style="background-color:#cccccc"
|Tl||Thallium||Greek thallos||81||&204.38332204.3833(2)||13||6
|-style="background-color:#ffbfff"
|Tm||Thulium||Thule and the traditional -ium ending||69||&168.934212168.93421(2)|| ||6
|-style="background-color:#ff99cc"
|U||Uranium||Uranus||92||&238.028913238.02891(3)|| ||7
|-style="background-color:#e8e8e8"
|Uuh||Ununhexium||Latin uni, uni, and Greek hex||116||&292[292]||16||7
|-style="background-color:#e8e8e8"
|Uuo||Ununoctium||Latin uni, uni, and oct||118||&294[294]||18||7
|-style="background-color:#e8e8e8"
|Uup||Ununpentium||Latin uni, uni, and Greek pent||115||&288[288]||15||7
|-style="background-color:#e8e8e8"
|Uuq||Ununquadium||Latin uni, uni, and quadr||114||&289[289]||14||7
|-style="background-color:#e8e8e8"
|Uus||Ununseptium||Latin uni, uni, and Greek sept||117||&295[295]||17||7
|-style="background-color:#e8e8e8"
|Uut||Ununtrium||Latin uni, uni, and Greek tri||113||&284[284]||13||7
|-style="background-color:#ffc0c0"
|V||Vanadium||Vanadis||23||&050.9415150.9415(1)||5||4
|-style="background-color:#ffc0c0"
|W||Tungsten||German wolfram||74||&183.841183.84(1)||6||6
|-style="background-color:#c0ffff"
|Xe||Xenon||Greek xenos||54||&131.2936131.293(6)||18||5
|-style="background-color:#ffc0c0"
|Y||Yttrium||Ytterby, Sweden||39||&088.90585288.90585(2)||3||5
|-style="background-color:#ffbfff"
|Yb||Ytterbium||Ytterby, Sweden||70||&173.043173.04(3)|| ||6
|-style="background-color:#ffc0c0"
|Zn||Zinc||German zink||30||&065.409465.409(4)||12||4
|-style="background-color:#ffc0c0"
|Zr||Zirconium||zircon||40||&091.224291.224(2)||4||5
|}

Symbols not currently used
The following is a list of names formerly used or suggested for use in naming the elements listed above.  Also included in this list are placeholder names and names given by discredited claimants for discovery.  Names which retain local use (as with aluminum and jod, for aluminium and iodine respectively) are not included in this table.
Chemical symbolNameAtomic numberOrigin of symbolWhy not usedAArgon18Current symbol is Ar. Name changed due to a standardization of, modernization of, or update to older formerly-used symbol. AbAlabamine85Discredited claim to discovery of astatine. Name designated by discredited/disputed claimant. AmAlabamium85Discredited claim to discovery of astatine. AnAthenium99Proposed name for einsteinium. Name proposed prior to discovery/creation of element or prior to official re-naming of a placeholder name. AoAusonium93Discredited claim to discovery of neptunium. AzAzote7Former name for nitrogen. BvBrevium91Former name for protactinium. BzBerzelium59Suggested name for praseodymium. CbColumbium41Former name of niobium. CbColumbium95Suggested name for americium. CpCassiopeium71Former name for lutetium. CtCenturium100Proposed name for fermium. CtCeltium72Former name of hafnium. DaDanubium43Suggested name for technetium. DbDubnium104Proposed name for rutherfordium.  The symbol and name were used for element 105. EbEkaboron21Name given by Mendeleev to an as of then undiscovered element. When discovered, scandium closely matched the prediction. Temporary placeholder name. ElEkaaluminium31Name given by Mendeleev to an as of then undiscovered element. When discovered, gallium closely matched the prediction. 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). EmEkamangan43Name given by Mendeleev to an as of then undiscovered element. When discovered, technetium closely matched the prediction. EsEkasilicon32Name given by Mendeleev to an as of then undiscovered element. When discovered, germanium closely matched the prediction. EsEsperium94Discredited claim to discovery of plutonium. FaFrancium87Current symbol is Fr. FrFlorentium61Discredited claim to discovery of promethium. GlGlucinium4Former name of beryllium. HaHahnium105Proposed name for dubnium. HaHahnium108Proposed name for hassium. IlIllinium61Discredited claim to discovery of promethium. JgJargonium72Discredited claim to discovery of hafnium. JoJoliotium105Proposed name for dubnium. KuKurchatovium104Proposed name for rutherfordium. LwLawrencium103Current symbol is Lr. MMuriaticum17Former name of chlorine. MaMasurium43Disputed claim to discovery of technetium. MdMendelevium97Proposed name for berkelium.  The symbol and name were later used for element 101. MeMendelevium68Suggested name for erbium. MsMasrium49Discredited claim of discovery of indium. MtMeitnium91Suggested name for protactinium. MvMendelevium101Current symbol is Md. NgNorwegium72Discredited claim to discovery of hafnium. NiNiton86Former name for radon. NoNorium72Discredited claim to discovery of hafnium. NsNielsbohrium105Proposed name for dubnium. NsNielsbohrium107Proposed name for bohrium. NtNiton86Suggested name for radon. NyNeoytterbium70Former name of ytterbium. OdOdinium62Suggested name for samarium. PePelopium41Former name for niobium. PoPotassium19Current symbol is K. RfRutherfordium106Proposed name for seaborgium.  The symbol and name were instead used for element 104. SaSamarium62Current symbol is Sm. Soසෝඩියම්11Current symbol is Na. SpSpectrium70Suggested name for ytterbium. StAntimony51Current symbol is Sb. TnTungsten74Current symbol is W. TuThulium69Current symbol is Tm. TuTungsten74Current symbol is W. TyTyrium60Suggested name for neodymium. UnbUnnilbium102Temporary name given to nobelium until it was permanently named by IUPAC. UneUnnilennium109Temporary name given to meitnerium until it was permanently named by IUPAC. UnhUnnilhexium106Temporary name given to seaborgium until it was permanently named by IUPAC. UnoUnniloctium108Temporary name given to hassium until it was permanently named by IUPAC. UnpUnnilpentium105Temporary name given to dubnium until it was permanently named by IUPAC. UnqUnnilquadium104Temporary name given to rutherfordium until it was permanently named by IUPAC. UnsUnnilseptium107Temporary name given to bohrium until it was permanently named by IUPAC. UntUnniltrium103Temporary name given to lawrencium until it was permanently named by IUPAC. UnuUnnilunium101Temporary name given to mendelevium until it was permanently named by IUPAC. UubUnunbium112Temporary name given to copernicium until it was permanently named by IUPAC. UunUnunnilium110Temporary name given to darmstadtium until it was permanently named by IUPAC. UuuUnununium111Temporary name given to roentgenium until it was permanently named by IUPAC. ViVirginium87Discredited claim to discovery of francium. VmVirginium87Discredited claim to discovery of francium. YtYttrium39Current symbol is Y. 

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 Traditional Chinese elements.  Modern alphabetic notation was introduced in 1814 by Jöns Jakob Berzelius.
Chemical symbolOriginal nameModern nameAtomic numberOrigin of symbolWhy Not Used20pxHydrogenHydrogen1Daltonian symbol circa 1808. 20pxSulfurSulfur16Alchemical symbol. 20pxPallasSulfur16Alchemical symbol. 20pxSulfurSulfur16Daltonian symbol circa 1808. ⊛MagnesiumMagnesium21Alchemical symbol. ♂MarsIron26Alchemical symbol. 20pxStellae Fixaeතඹ29Pre-16th century alchemical symbol. ♀Venusතඹ29Alchemical symbol. 20pxCopperතඹ29Alchemical symbol. ©Copperතඹ29Daltonian symbol circa 1808. 20pxArsenicArsenic33Alchemical symbol. ☽LunaSilver47Alchemical symbol. 20pxIupiterTin50Alchemical symbol. ♁AntimonyAntimony51Alchemical symbol. ☉☾PlatinumPlatinum78Alchemical symbol. 20pxUranusPlatinum78Alchemical symbol. ☼SolGold79Alchemical symbol from the 16th century20pxSolGold79Alchemical symbol from 1700 through 1783. PiscesMercury80Pre-16th century alchemical symbol. 20pxNeptunusMercury80Alchemical symbol from the 17th century. 20pxMercuriusMercury80Alchemical symbol from 1700 through 1783. 20pxSaturnusLead82Alchemical symbol circa 1783. 20pxTaurusBismuth83Alchemical 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 Index to isotope pages 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.  Although it is not an isotope, this is perhaps the most useful place to mention that H is the proposed symbol for the only created anti-element, antihydrogen.
Chemical SymbolNameAtomic NumberOrigin of SymbolAcActinium89From 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
General:
E: any element
M: metal - any metal atom
Mu: muonium
Ps: positronium
X: halogen - any halogen atom

From organic chemistry:
Ac: acetyl - (also used for the element actinium: see above)
Ar: aryl - (also used for the element argon: see above)
Bn: benzyl
Bu: butyl
Bz: benzoyl or benzyl - (also used for berzelium, an old suggested name for praseodymium).
Cp: cyclopentadienyl
Cy: cyclohexyl
Et: ethyl
Me: methyl
Ms: mesyl (methylsulfonyl)
Ph: phenyl
Pr: propyl - (also used for the element praseodymium: see above)
R: radical - some unspecified element or radical
Tf: triflyl (trifluoromethanesulfonyl)
Tr: trityl (triphenylmethyl)
Ts: tosyl

From inorganic chemistry:
Ab: albite
Di: didymium - Rare earth metal that proved to be a mixture of the elements praseodymium and neodymium.
Dp: decipium - Rare earth metal that proved to be a mixture of the elements samarium, neodymium and praseodymium.
Pp: philippium - rare earth metal that proved to be a mixture of the elements holmium and samarium.

 Notes 

 References 
Element name etymologies. Retrieved July 15, 2005.
Atomic Weights of the Elements 2001, Pure Appl. Chem. 75(8), 1107-1122, 2003. Retrieved June 30, 2005.  Atomic weights of elements with atomic numbers from 1-109 taken from this source.
IUPAC Standard Atomic Weights Revised  (2005).
WebElements Periodic Table. Retrieved June 30, 2005.  Atomic weights of elements with atomic numbers 110-116 taken from this source.
Lapp, Ralph E.  Matter.  Life Science Library.  New York: Time Incorporated.  1963.
Leighton, Robert B.  Principles of Modern Physics''.  New York: McGraw-Hill.  1959.

 External links 
Berzelius’ List of Elements
History of IUPAC Atomic Weight Values (1883 to 1997)

Category:Lists of chemical elements
Category:Lists of symbols