Chemical symbol

thumb|upright=2.2|The [[periodic table, elements being denoted by their symbols]]

Chemical symbols are the abbreviations used in chemistry, mainly for chemical elements, but also for functional groups, chemical compounds, and other entities. Element symbols for chemical elements, also known as atomic symbols, normally consist of one or two letters from the Latin alphabet and are written with the first letter capitalised.

History

Earlier symbols for chemical elements stem from classical Latin and Greek words. For some elements, this is because the material was known in ancient times, while for others, the name is a more recent invention. For example, Pb is the symbol for lead (plumbum in Latin); Hg is the symbol for mercury (hydrargyrum in Greek); and He is the symbol for helium (a Neo-Latin name) because helium was not known in ancient Roman times. Some symbols come from other sources, like W for tungsten (Wolfram in German) which was not known in Roman times.

A three-letter temporary symbol may be assigned to a newly synthesized (or not yet synthesized) element. For example, "Uno" was the temporary symbol for hassium (element 108) which had the temporary name of unniloctium, based on the digits of its atomic number. There are also some historical symbols that are no longer officially used.

Extension of the symbol

thumb|upright=1.5|Annotated example of an atomic symbol

In addition to the letters for the element itself, additional details may be added to the symbol as superscripts or subscripts a particular isotope, ionization, or oxidation state, or other atomic detail. A few isotopes have their own specific symbols rather than just an isotopic detail added to their element symbol.

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

• The nucleon number (mass number) is shown in the left superscript position (e.g., ¹⁴N). This number defines the specific isotope. Various letters, such as "m" and "f" may also be used here to indicate a nuclear isomer (e.g., ^99mTc). Alternately, the number here can represent a specific spin state (e.g., ¹O₂). These details can be omitted if not relevant in a certain context.
• The proton number (atomic number) may be indicated in the left subscript position (e.g., ₆₄Gd). The atomic number is redundant to the chemical element, but is sometimes used to emphasize the change of numbers of nucleons in a nuclear reaction.
• If necessary, a state of ionization or an excited state may be indicated in the right superscript position (e.g., state of ionization Ca²⁺).
• The number of atoms of an element in a molecule or chemical compound is shown in the right subscript position (e.g., N₂ or Fe₂O₃). If this number is one, it is normally omitted: the number one is implicitly understood if unspecified.
• A radical is indicated by a dot on the right side (e.g., Cl^• for a neutral chlorine atom). This is often omitted unless relevant to a certain context because it is already deducible from the charge and atomic number, as generally true for nonbonded valence electrons in skeletal structures.

Many functional groups also have their own chemical symbol, e.g. Ph for the phenyl group, and Me for the methyl group.

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 for chemical elements

{| class="wikitable sortable sort-under sticky-header-multi" style="font-size:90%"

|+

! colspan="4" | List of chemical elements

|-

!Z

!Symbol

!Name

!Origin of name

|-

| 1 || H || Hydrogen || Greek hydro- and -gen, meaning 'water-forming'

|-

| 2 || He || Helium || Greek hḗlios, 'sun'

|-

| 3 || Li || Lithium || Greek líthos, 'stone'

|-

| 4 || Be || Beryllium || beryl, a mineral (ultimately from the name of Belur in southern India)

|-

| 5 || B || Boron || borax, a mineral (from Arabic bawraq)

|-

| 6 || C || Carbon || Latin carbo, 'coal'

|-

| 7 || N || Nitrogen || Greek nítron and -gen, meaning 'niter-forming'

|-

| 8 || O || Oxygen || Greek oxy- and -gen, meaning 'acid-forming'

|-

| 9 || F || Fluorine || Latin fluere, 'to flow'

|-

| 10 || Ne || Neon || Greek néon, 'new'

|-

| 11 || Na || Sodium || English soda (the symbol Na is derived from Neo-Latin natrium, coined from German Natron, 'natron')

|-

| 12 || Mg || Magnesium || Magnesia, a district of Eastern Thessaly in Greece

|-

| 13 || Al || Aluminium || alumina, from Latin alumen (gen. alumni), 'bitter salt, alum'

|-

| 14 || Si || Silicon || Latin silex, 'flint' (originally silicium)

|-

| 15 || P || Phosphorus || Greek phōsphóros, 'light-bearing'

|-

| 16 || S || Sulfur || Latin sulphur, 'brimstone'

|-

| 17 || Cl || Chlorine || Greek chlōrós, 'greenish yellow'

|-

| 18 || Ar || Argon || Greek argós, 'idle' (because of its inertness)

|-

| 19 || K || Potassium || Neo-Latin potassa, 'potash' (the symbol K is derived from Latin kalium)

|-

| 20 || Ca || Calcium || Latin calx, 'lime'

|-

| 21 || Sc || Scandium || Latin Scandia, 'Scandinavia'

|-

| 22 || Ti || Titanium || Titans, the sons of the Earth goddess of Greek mythology

|-

| 23 || V || Vanadium || Vanadis, an Old Norse name for the Scandinavian goddess Freyja

|-

| 24 || Cr || Chromium || Greek chróma, 'colour'

|-

| 25 || Mn || Manganese || corrupted from magnesia negra; see Magnesium

|-

| 26 || Fe || Iron || English word, ultimately from Proto-Celtic *īsarnom, a word related to the Celtic word for "blood" (the symbol Fe is derived from Latin ferrum)

|-

| 27 || Co || Cobalt || German Kobold, 'goblin'

|-

| 28 || Ni || Nickel || Nickel, a mischievous sprite of German miner mythology

|-

| 29 || Cu || Copper || English word, from Latin cuprum, from Ancient Greek Kýpros 'Cyprus'

|-

| 30 || Zn || Zinc || Most likely from German Zinke, 'prong' or 'tooth', though some suggest Persian sang, 'stone'

|-

| 31 || Ga || Gallium || Latin Gallia, 'France'

|-

| 32 || Ge || Germanium || Latin Germania, 'Germany'

|-

| 33 || As || Arsenic || French arsenic, from Greek arsenikón 'yellow arsenic' (influenced by arsenikós, 'masculine' or 'virile'), from a West Asian wanderword ultimately from Old Iranian *zarniya-ka, 'golden'

|-

| 34 || Se || Selenium || Greek selḗnē, 'moon'

|-

| 35 || Br || Bromine || Greek brômos, 'stench'

|-

| 36 || Kr || Krypton || Greek kryptós, 'hidden'

|-

| 37 || Rb || Rubidium || Latin rubidus, 'deep red'

|-

| 38 || Sr || Strontium || Strontian, a village in Scotland

|-

| 39 || Y || Yttrium || Ytterby, a village in Sweden

|-

| 40 || Zr || Zirconium || zircon, a mineral

|-

| 41 || Nb || Niobium || Niobe, daughter of king Tantalus from Greek mythology

|-

| 42 || Mo || Molybdenum || Greek molýbdaina, 'piece of lead', from mólybdos, 'lead'

|-

| 43 || Tc || Technetium || Greek tekhnētós, 'artificial'

|-

| 44 || Ru || Ruthenium || Neo-Latin Ruthenia, 'Russia'

|-

| 45 || Rh || Rhodium || Greek rhodóeis, 'rose-coloured', from rhódon, 'rose'

|-

| 46 || Pd || Palladium || the asteroid Pallas, considered a planet at the time

|-

| 47 || Ag || Silver || English word, ultimately from Proto-Germanic *silubrą (The symbol derives from Latin argentum)

|-

| 48 || Cd || Cadmium || Neo-Latin cadmia, from King Kadmos

|-

| 49 || In || Indium || Latin indicum, 'indigo' (colour found in its spectrum)

|-

| 50 || Sn || Tin || English word, ultimately from Proto-Germanic *tiną, perhaps meaning "shining" (The symbol derives from Latin stannum)

|-

| 51 || Sb || Antimony || Latin antimonium, the origin of which is uncertain: folk etymologies suggest it is derived from Greek antí ('against') + mónos ('alone'), or Old French anti-moine, 'Monk's bane', but it could plausibly be from or related to Arabic ʾiṯmid, 'antimony', reformatted as a Latin word. (The symbol derives from Latin stibium 'stibnite'.)

|-

| 52 || Te || Tellurium || Latin tellus, 'the ground, earth'

|-

| 53 || I || Iodine || French iode, from Greek ioeidḗs, 'violet'

|-

| 54 || Xe || Xenon || Greek xénon, neuter form of xénos 'strange'

|-

| 55 || Cs || Caesium || Latin caesius, 'sky-blue'

|-

| 56 || Ba || Barium || Greek barýs, 'heavy'

|-

| 57 || La || Lanthanum || Greek lanthánein, 'to lie hidden'

|-

| 58 || Ce || Cerium || the dwarf planet Ceres, considered a planet at the time

|-

| 59 || Pr || Praseodymium || Greek prásios dídymos, 'green twin'

|-

| 60 || Nd || Neodymium || Greek néos dídymos, 'new twin'

|-

| 61 || Pm || Promethium || Prometheus of Greek mythology

|-

| 62 || Sm || Samarium || samarskite, a mineral named after Colonel Vasili Samarsky-Bykhovets, Russian mine official

|-

| 63 || Eu || Europium || Europe

|-

| 64 || Gd || Gadolinium || gadolinite, a mineral named after Johan Gadolin, Finnish chemist, physicist and mineralogist

|-

| 65 || Tb || Terbium || Ytterby, a village in Sweden

|-

| 66 || Dy || Dysprosium || Greek dysprósitos, 'hard to get'

|-

| 67 || Ho || Holmium || Neo-Latin Holmia, 'Stockholm'

|-

| 68 || Er || Erbium || Ytterby, a village in Sweden

|-

| 69 || Tm || Thulium || Thule, the ancient name for an unclear northern location

|-

| 70 || Yb || Ytterbium || Ytterby, a village in Sweden

|-

| 71 || Lu || Lutetium || Latin Lutetia, 'Paris'

|-

| 72 || Hf || Hafnium || Neo-Latin Hafnia, 'Copenhagen' (from Danish havn)

|-

| 73 || Ta || Tantalum || King Tantalus, father of Niobe from Greek mythology

|-

| 74 || W || Tungsten || Swedish tung sten, 'heavy stone' (The symbol is from wolfram, the old name of the tungsten mineral wolframite)

|-

| 75 || Re || Rhenium || Latin Rhenus, 'the Rhine'

|-

| 76 || Os || Osmium || Greek osmḗ, 'smell'

|-

| 77 || Ir || Iridium || Iris, the Greek goddess of the rainbow

|-

| 78 || Pt || Platinum || Spanish platina, 'little silver', from plata 'silver'

|-

| 79 || Au || Gold || English word, ultimately from Proto-Indo-European *ǵʰl̥h₃tóm, related to "yellow" (The symbol derives from Latin aurum)

|-

| 80 || Hg || Mercury || Mercury, Roman god of commerce, communication, and luck, known for his speed and mobility (The symbol is from the element's Latin name hydrargyrum, derived from Greek hydrárgyros, 'water-silver')

|-

| 81 || Tl || Thallium || Greek thallós, 'green shoot or twig'

|-

| 82 || Pb || Lead || English word, from Proto-Celtic *ɸloudom, from Proto-Indo-European *plewd-, “flow” (The symbol derives from Latin plumbum)

|-

| 83 || Bi || Bismuth || German Wismut, from weiß Masse 'white mass', unless from Arabic

|-

| 84 || Po || Polonium || Latin Polonia, 'Poland' (the home country of Marie Curie)

|-

| 85 || At || Astatine || Greek ástatos, 'unstable'

|-

| 86 || Rn || Radon || Radium

|-

| 87 || Fr || Francium || France

|-

| 88 || Ra || Radium || French radium, from Latin radius, 'ray'

|-

| 89 || Ac || Actinium || Greek aktís, 'ray'

|-

| 90 || Th || Thorium || Thor, the Scandinavian god of thunder

|-

| 91 || Pa || Protactinium || proto- (from Greek prôtos, 'first, before') + actinium, which is produced through the radioactive decay of protactinium

|-

| 92 || U || Uranium || Uranus, the seventh planet in the Solar System

|-

| 93 || Np || Neptunium || Neptune, the eighth planet in the Solar System

|-

| 94 || Pu || Plutonium || the dwarf planet Pluto, considered the ninth planet in the Solar System at the time

|-

| 95 || Am || Americium || The Americas, as the element was first synthesised on the continent, by analogy with europium

|-

| 96 || Cm || Curium || Pierre Curie and Marie Curie, French physicists and chemists

|-

| 97 || Bk || Berkelium || Berkeley, California, where the element was first synthesised, by analogy with terbium

|-

| 98 || Cf || Californium || California, where the element was first synthesised

|-

| 99 || Es || Einsteinium || Albert Einstein, German physicist

|-

| 100 || Fm || Fermium || Enrico Fermi, Italian physicist

|-

| 101 || Md || Mendelevium || Dmitri Mendeleev, Russian chemist and inventor who proposed the periodic table

|-

| 102 || No || Nobelium || Alfred Nobel, Swedish chemist and engineer

|-

| 103 || Lr || Lawrencium || Ernest O. Lawrence, American physicist

|-

| 104 || Rf || Rutherfordium || Ernest Rutherford, New Zealand chemist and physicist

|-

| 105 || Db || Dubnium || Dubna, Russia, where the Joint Institute for Nuclear Research is located

|-

| 106 || Sg || Seaborgium || Glenn T. Seaborg, American chemist

|-

| 107 || Bh || Bohrium || Niels Bohr, Danish physicist

|-

| 108 || Hs || Hassium || Neo-Latin Hassia, 'Hesse' (a state in Germany)

|-

| 109 || Mt || Meitnerium || Lise Meitner, Austrian physicist

|-

| 110 || Ds || Darmstadtium|| Darmstadt, Germany, where the element was first synthesised

|-

| 111 || Rg || Roentgenium || Wilhelm Conrad Röntgen, German physicist

|-

| 112 || Cn || Copernicium || Nicolaus Copernicus, Polish astronomer

|-

| 113 || Nh || Nihonium || Japanese Nihon, 'Japan' (where the element was first synthesised)

|-

| 114 || Fl || Flerovium || Flerov Laboratory of Nuclear Reactions, part of JINR, where the element was synthesised; itself named after Georgy Flyorov, Russian physicist

|-

| 115 || Mc || Moscovium || Moscow Oblast, Russia, where the element was first synthesised

|-

| 116 || Lv || Livermorium || Lawrence Livermore National Laboratory in Livermore, California, which collaborated with JINR on its synthesis

|-

| 117 || Ts || Tennessine || Tennessee, United States

|-

| 118 || Og || Oganesson || Yuri Oganessian, Russian physicist

|-

|}

Symbols and names not currently used

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

{| class="wikitable sortable sticky-header" style

!Symbol!!Name!!Atomic<br/>number!!Notes!!Why not<br/>used!!Refs

|-

|A||Argon||18||A used for Argon until 1957. Current symbol is Ar. || ||

|-

|Ab||Alabamine||85||Discredited claim to discovery of astatine. || ||

|-

|Ad||Aldebaranium||70||Former name for ytterbium. || ||

|-

|Ao||Ausonium||93||Discredited claim to discovery of neptunium. ||

|-

|Cb||Columbium||41||Former name for niobium. ||

|-

|Da||Davyum||43||Discredited claim to discovery of technetium. || ||

|-

|Eb||Ekaboron||21||Name given by Mendeleev to an as of then undiscovered element. When discovered, scandium closely matched the prediction. ||

|-

|Np||Nipponium||43||Discredited claim to discovery of technetium. The symbol Np is now used for neptunium. ||

{| class="wikitable sticky-header" style

|+ Alchemical symbols for the modern elements

!colspan=2|Symbol!!Element!!Atomic<br/>number!!Notes

|-

| || style="text-align:center;" | || Phosphorus || 15 || (discovered late)

|-

| style="text-align:center;" | 24px || style="text-align:center;" | || Sulfur || 16 || used by Newton

|-

| style="text-align:center;" | 24px || || Manganese || 25 || late; used by Torbern Bergman (1775)

|-

| style="text-align:center;" | 24px || style="text-align:center;" | || Iron || 26 || classical planetary metal of Mars

|-

| style="text-align:center;" | 24px || style="text-align:center;" | || Cobalt || 27 || late; used by Bergman

|-

| style="text-align:center;" | 24px || || Nickel || 28 || late; used by Bergman (old positional variant of arsenic, previously used for regulus of sulfur)

|-

| style="text-align:center;" | 24px || || Zinc || 30 || late; used by Bergman

|-

| style="text-align:center;" | 24px || style="text-align:center;" | || Copper || 29 || classical planetary metal of Venus

|-

| style="text-align:center;" | 24px || style="text-align:center;" | || Arsenic || 33 ||

|-

| style="text-align:center;" | 24px || style="text-align:center;" | || rowspan="2" | Silver || rowspan="2" | 47 || classical planetary metal of the Moon

|-

| style="text-align:center;" | 24px || style="text-align:center;" | ||

|-

| style="text-align:center;" | 24px || style="text-align:center;" | || Tin || 50 || classical planetary metal of Jupiter

|-

| style="text-align:center;" | 24px || style="text-align:center;" | || Antimony || 51 || the newly discovered "eighth metal" was given the symbol for the Earth, which was recognized as a planet by that time

|-

| style="text-align:center;" | 24px || || rowspan="2" | Platinum || rowspan="2" | 78 || late; used by Bergman et al.: a compound of ☉ gold and ☾ silver

|-

| style="text-align:center;" | 24px || style="text-align:center;" | || late; symbol invented for the newly discovered planet Uranus so that it could also be used for newly recognized platinum

|-

| style="text-align:center;" | 24px || style="text-align:center;" | || rowspan="2" | Gold || rowspan="2" | 79 || classical variant

|-

| style="text-align:center;" | 24px || style="text-align:center;" | || medieval variant; planetary metal of the Sun

|-

| style="text-align:center;" | 24px || style="text-align:center;" | || Mercury || 80 || classical planetary metal of Mercury

|-

| style="text-align:center;" | 24px || style="text-align:center;" | || Lead || 82 || classical planetary metal of Saturn

|-

| style="text-align:center;" | 24px || style="text-align:center;" | || rowspan=2| Bismuth || rowspan=2| 83 || used by Newton

|-

| style="text-align:center;" | 24px || style="text-align:center;" | || used by Bergman

|}

Daltonian symbols

thumb|Dalton's symbols for the more common elements, as of 1806, and the relative weights he calculated. The symbols for magnesium and calcium ("lime") were replaced by 1808, and that for gold was simplified.

The following symbols were employed by John Dalton in the early 1800s as the periodic table of elements was being formulated. Not included in this list are symbols for compounds, such as certain rare-earth mineral blends. Modern alphabetic notation was introduced in 1814 by Jöns Jakob Berzelius; its precursor can be seen in Dalton's circled letters for the metals, especially in his augmented table from 1810.

A trace of Dalton's conventions also survives in ball-and-stick models of molecules, where balls for carbon are black and for oxygen red.

{| class="wikitable" style

|+Daltonian symbols for the elements

!colspan=2|Symbol!!rowspan=2|Dalton's name!!rowspan=2|Modern name!!rowspan=2|Atomic<br/>number!!rowspan=2|Notes!!rowspan=2|Refs

|-

!<small>img.</small>||<small>char.</small>

|-

| 24px ||<span style="color:red">☉</span>||colspan=2|hydrogen||1||or <span style="color:red">⊙</span>||

|-

| 24px || ||glucine||beryllium||4||alchemical symbol for 'sugar'||

|-

| 24px || ||colspan=2|phosphorus||15||(3 radii)||

The symbols for isotopes of elements other than hydrogen and radon are no longer used in the scientific community. Many of these symbols were designated during the early years of radiochemistry, and several isotopes (namely those in the decay chains of actinium, radium, and thorium) bear placeholder names using the early naming system devised by Ernest Rutherford.

{| class="wikitable sortable sticky-header" style

!Symbol!!Name!!Atomic<br/>number!!class="unsortable"|Origin of symbol

|-

|Ac||Actinium||89||From Greek aktinos. Name restricted at one time to Ac, an isotope of actinium. This named isotope later became the official name for element 89.

|-

|AcA||Actinium A||84||From actinium and A. Placeholder name given at one time to Po, an isotope of polonium identified in the decay chain of actinium.

|-

|AcB||Actinium B||82||From actinium and B. Placeholder name given at one time to Pb, an isotope of lead identified in the decay chain of actinium.

|-

|AcC||Actinium C||83||From actinium and C. Placeholder name given at one time to Bi, an isotope of bismuth identified in the decay chain of actinium.

|-

|AcC′||Actinium C′||84||From actinium and C′. Placeholder name given at one time to Po, an isotope of polonium identified in the decay chain of actinium.

|-

|AcC″||Actinium C″||81||From actinium and C″. Placeholder name given at one time to ²⁰⁷Tl, an isotope of thallium identified in the decay chain of actinium.

|-

|AcK||Actinium K||87||Name given at one time to ²²³Fr, an isotope of francium identified in the decay chain of actinium.

|-

|AcU||Actino-uranium||92||Name given at one time to ²³⁵U, an isotope of uranium.

|-

|AcX||Actinium X||88||Name given at one time to ²²³Ra, an isotope of radium identified in the decay chain of actinium.

|-

|An||Actinon||86||From actinium and emanation. Name given at one time to ²¹⁹Rn, an isotope of radon identified in the decay chain of actinium.

|-

|D||Deuterium||1||From the Greek deuteros. Name given to ²H.

|-

|Io||Ionium||90||Name given to ²³⁰Th, an isotope of thorium identified in the decay chain of uranium.

|-

|MsTh₁||Mesothorium 1||88||Name given at one time to ²²⁸Ra, an isotope of radium.

|-

|MsTh₂||Mesothorium 2||89||Name given at one time to ²²⁸Ac, an isotope of actinium.

|-

|Pa||Protactinium||91||From 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.

|-

|Ra||Radium||88||From 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.

|-

|RaA||Radium A||84||From radium and A. Placeholder name given at one time to ²¹⁸Po, an isotope of polonium identified in the decay chain of radium.

|-

|RaB||Radium B||82||From radium and B. Placeholder name given at one time to ²¹⁴Pb, an isotope of lead identified in the decay chain of radium.

|-

|RaC||Radium C||83||From 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′||84||From 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″||81||From radium and C″. Placeholder name given at one time to ²¹⁰Tl, an isotope of thallium identified in the decay chain of radium.

|-

|RaD||Radium D||82||From radium and D. Placeholder name given at one time to ²¹⁰Pb, an isotope of lead identified in the decay chain of radium.

|-

|RaE||Radium E||83||From 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″||81||From radium and E″. Placeholder name given at one time to ²⁰⁶Tl, an isotope of thallium identified in the decay chain of radium.

|-

|RaF||Radium F||84||From radium and F. Placeholder name given at one time to ²¹⁰Po, an isotope of polonium identified in the decay chain of radium.

|-

|RdAc||Radioactinium||90||Name given at one time to ²²⁷Th, an isotope of thorium.

|-

|RdTh||Radiothorium||90||Name given at one time to ²²⁸Th, an isotope of thorium.

|-

|Rn||Radon||86||From 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.

|-

|T||Tritium||1||From the Greek tritos. Name given to ³H.

|-

|Th||Thorium||90||After Thor. Name restricted at one time to ²³²Th, an isotope of thorium. This named isotope later became the official name for element 90.

|-

|ThA||Thorium A||84||From thorium and A. Placeholder name given at one time to ²¹⁶Po, an isotope of polonium identified in the decay chain of thorium.

|-

|ThB||Thorium B||82||From thorium and B. Placeholder name given at one time to ²¹²Pb, an isotope of lead identified in the decay chain of thorium.

|-

|ThC||Thorium C||83||From 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′||84||From 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″||81||From thorium and C″. Placeholder name given at one time to ²⁰⁸Tl, an isotope of thallium identified in the decay chain of thorium.

|-

|ThX||Thorium X||88||Name given at one time to ²²⁴Ra, an isotope of radium identified in the decay chain of thorium.

|-

|Tn||Thoron||86||From thorium and emanation. Name given to ²²⁰Rn, an isotope of radon identified in the decay chain of thorium.

|-

|UI||Uranium I||92||Name given at one time to ²³⁸U, an isotope of uranium.

|-

|UII||Uranium II||92||Name given at one time to ²³⁴U, an isotope of uranium.

|-

|UX₁||Uranium X₁||90||Name given at one time to ²³⁴Th, an isotope of thorium identified in the decay chain of uranium.

|-

|UX₂||Uranium X₂||91||Name given at one time to ^234mPa, an isotope of protactinium identified in the decay chain of uranium.

|-

|UY||Uranium Y||90||Name given at one time to ²³¹Th, an isotope of thorium identified in the decay chain of uranium.

|-

|UZ||Uranium Z||91||Name given at one time to ²³⁴Pa, an isotope of protactinium identified in the decay chain of uranium.

|}

Other symbols

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

General:

• A: A deprotonated acid or an anion
• An: any actinide
• B: A base, often in the context of Lewis acid–base theory or Brønsted–Lowry acid–base theory
• E: any element or electrophile
• L: any ligand
• Ln: any lanthanide
• M: any metal
• Mm: mischmetal (occasionally used)
• Ng: any noble gas (Rg is sometimes used, but that is also used for the element roentgenium: see above)
• Nu: any nucleophile
• R: any unspecified radical (moiety) not important to the discussion
• St: steel (occasionally used)
• X: any halogen (or sometimes pseudohalogen)

From organic chemistry:

• Ac: acetyl – (also used for the element actinium: see above)
• Ad: 1-adamantyl
• All: allyl
• Am: amyl (pentyl) – (also used for the element americium: see above)
• Ar: aryl – (also used for the element argon: see above)
• Bn: benzyl
• Bs: brosyl or (outdated) benzenesulfonyl
• Bu: butyl (i-, s-, or t- prefixes may be used to denote iso-, sec-, or tert- isomers, respectively)
• Bz: benzoyl
• Cp: cyclopentadienyl
• Cp*: pentamethylcyclopentadienyl
• Cy: cyclohexyl
• Cyp: cyclopentyl
• Et: ethyl
• Me: methyl
• Mes: mesityl (2,4,6-trimethylphenyl)
• Ms: mesyl (methylsulfonyl)
• Np: neopentyl – (also used for the element neptunium: see above)
• Ns: nosyl
• Pent: pentyl
• Ph, Φ: phenyl
• Pr: propyl – (i- prefix may be used to denote isopropyl. Also used for the element praseodymium: see above)
• R: In organic chemistry contexts, an unspecified "R" is often understood to be an alkyl group
• Tf: triflyl (trifluoromethanesulfonyl)
• Tr, Trt: trityl (triphenylmethyl)
• Ts, Tos: tosyl (para-toluenesulfonyl) – (Ts also used for the element tennessine: see above)
• Vi: vinyl

From organometallic chemistry:

• Fc, ferrocenyl:
• Fp, (Cyclopentadienyl)iron dicarbonyl:

Exotic atoms:

• Mu: muonium
• Pn: protonium
• Ps: positronium

See also

• List of chemical elements naming controversies
• List of elements
• Nuclear notation

Notes

References

• Elementymology & Elements Multidict, 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.
• Leighton, Robert B. Principles of Modern Physics. New York: McGraw-Hill. 1959.
• Scerri, E.R. "The Periodic Table, Its Story and Its Significance". New York, Oxford University Press. 2007.

External links

• Berzelius' List of Elements
• History of IUPAC Atomic Weight Values (1883 to 1997)
• Committee on Nomenclature, Terminology, and Symbols , American Chemical Society