Chemical symbol explained

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 vocabulary. 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

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.^[1] 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

List of chemical elements

Z	Symbol	Name	Origin of name^[2] ^[3]
1	H		Greek elements hydro- and -gen, meaning 'water-forming'
2	He		Greek hḗlios, 'sun'
3	Li		Greek líthos, 'stone'
4	Be		beryl, a mineral (ultimately from the name of Belur in southern India)
5	B		borax, a mineral (from Arabic bawraq)
6	C		Latin carbo, 'coal'
7	N		Greek nítron and -gen, meaning 'niter-forming'
8	O		Greek oxy- and -gen, meaning 'acid-forming'
9	F		Latin fluere, 'to flow'
10	Ne		Greek néon, 'new'
11	Na		English soda (the symbol Na is derived from Neo-Latin natrium, coined from German Natron, 'natron')
12	Mg		Magnesia, a district of Eastern Thessaly in Greece
13	Al		alumina, from Latin alumen (gen. alumni), 'bitter salt, alum'
14	Si		Latin silex, 'flint' (originally silicium)
15	P		Greek phōsphóros, 'light-bearing'
16	S		Latin sulphur, 'brimstone'
17	Cl		Greek chlōrós, 'greenish yellow'
18	Ar		Greek argós, 'idle' (because of its inertness)
19	K		Neo-Latin potassa, 'potash' (the symbol K is derived from Latin kalium)
20	Ca		Latin calx, 'lime'
21	Sc		Latin Scandia, 'Scandinavia'
22	Ti		Titans, the sons of the Earth goddess of Greek mythology
23	V		Vanadis, an Old Norse name for the Scandinavian goddess Freyja
24	Cr		Greek chróma, 'colour'
25	Mn		corrupted from magnesia negra; see Magnesium
26	Fe		English word (the symbol Fe is derived from Latin ferrum)
27	Co		German Kobold, 'goblin'
28	Ni		Nickel, a mischievous sprite of German miner mythology
29	Cu		English word, from Latin cuprum, from Ancient Greek Kýpros 'Cyprus'
30	Zn		Most likely from German Zinke, 'prong' or 'tooth', though some suggest Persian sang, 'stone'
31	Ga		Latin Gallia, 'France'
32	Ge		Latin Germania, 'Germany'
33	As		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		Greek selḗnē, 'moon'
35	Br		Greek brômos, 'stench'
36	Kr		Greek kryptós, 'hidden'
37	Rb		Latin rubidus, 'deep red'
38	Sr		Strontian, a village in Scotland
39	Y		Ytterby, a village in Sweden
40	Zr		zircon, a mineral
41	Nb		Niobe, daughter of king Tantalus from Greek mythology
42	Mo		Greek molýbdaina, 'piece of lead', from mólybdos, 'lead'
43	Tc		Greek tekhnētós, 'artificial'
44	Ru		Neo-Latin Ruthenia, 'Russia'
45	Rh		Greek rhodóeis, 'rose-coloured', from rhódon, 'rose'
46	Pd		the asteroid Pallas, considered a planet at the time
47	Ag		English word (The symbol derives from Latin argentum)
48	Cd		Neo-Latin cadmia, from King Kadmos
49	In		Latin indicum, 'indigo' (colour found in its spectrum)
50	Sn		English word (The symbol derives from Latin stannum)
51	Sb		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		Latin tellus, 'the ground, earth'
53	I		French iode, from Greek ioeidḗs, 'violet'
54	Xe		Greek xénon, neuter form of xénos 'strange'
55	Cs		Latin caesius, 'sky-blue'
56	Ba		Greek barýs, 'heavy'
57	La		Greek lanthánein, 'to lie hidden'
58	Ce		the dwarf planet Ceres, considered a planet at the time
59	Pr		Greek prásios dídymos, 'green twin'
60	Nd		Greek néos dídymos, 'new twin'
61	Pm		Prometheus of Greek mythology
62	Sm		samarskite, a mineral named after Colonel Vasili Samarsky-Bykhovets, Russian mine official
63	Eu		Europe
64	Gd		gadolinite, a mineral named after Johan Gadolin, Finnish chemist, physicist and mineralogist
65	Tb		Ytterby, a village in Sweden
66	Dy		Greek dysprósitos, 'hard to get'
67	Ho		Neo-Latin Holmia, 'Stockholm'
68	Er		Ytterby, a village in Sweden
69	Tm		Thule, the ancient name for an unclear northern location
70	Yb		Ytterby, a village in Sweden
71	Lu		Latin Lutetia, 'Paris'
72	Hf		Neo-Latin Hafnia, 'Copenhagen' (from Danish havn)
73	Ta		King Tantalus, father of Niobe from Greek mythology
74	W		Swedish tung sten, 'heavy stone' (The symbol is from wolfram, the old name of the tungsten mineral wolframite)
75	Re		Latin Rhenus, 'the Rhine'
76	Os		Greek osmḗ, 'smell'
77	Ir		Iris, the Greek goddess of the rainbow
78	Pt		Spanish platina, 'little silver', from plata 'silver'
79	Au		English word (The symbol derives from Latin aurum)
80	Hg		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		Greek thallós, 'green shoot or twig'
82	Pb		English word (The symbol derives from Latin plumbum)
83	Bi		German Wismut, from weiß Masse 'white mass', unless from Arabic
84	Po		Latin Polonia, 'Poland' (the home country of Marie Curie)
85	At		Greek ástatos, 'unstable'
86	Rn		radium
87	Fr		France
88	Ra		French radium, from Latin radius, 'ray'
89	Ac		Greek aktís, 'ray'
90	Th		Thor, the Scandinavian god of thunder
91	Pa		proto- (from Greek prôtos, 'first, before') + actinium, which is produced through the radioactive decay of protactinium
92	U		Uranus, the seventh planet in the Solar System
93	Np		Neptune, the eighth planet in the Solar System
94	Pu		the dwarf planet Pluto, considered the ninth planet in the Solar System at the time
95	Am		The Americas, as the element was first synthesised on the continent, by analogy with europium
96	Cm		Pierre Curie and Marie Curie, French physicists and chemists
97	Bk		Berkeley, California, where the element was first synthesised, by analogy with terbium
98	Cf		California, where the element was first synthesised
99	Es		Albert Einstein, German physicist
100	Fm		Enrico Fermi, Italian physicist
101	Md		Dmitri Mendeleev, Russian chemist and inventor who proposed the periodic table
102	No		Alfred Nobel, Swedish chemist and engineer
103	Lr		Ernest O. Lawrence, American physicist
104	Rf		Ernest Rutherford, New Zealand chemist and physicist
105	Db		Dubna, Russia, where the Joint Institute for Nuclear Research is located
106	Sg		Glenn T. Seaborg, American chemist
107	Bh		Niels Bohr, Danish physicist
108	Hs		Neo-Latin Hassia, 'Hesse' (a state in Germany)
109	Mt		Lise Meitner, Austrian physicist
110	Ds	Darmstadtium	Darmstadt, Germany, where the element was first synthesised
111	Rg		Wilhelm Conrad Röntgen, German physicist
112	Cn		Nicolaus Copernicus, Polish astronomer
113	Nh		Japanese Nihon, 'Japan' (where the element was first synthesised)
114	Fl		Flerov Laboratory of Nuclear Reactions, part of JINR, where the element was synthesised; itself named after Georgy Flyorov, Russian physicist
115	Mc		Moscow Oblast, Russia, where the element was first synthesised
116	Lv		Lawrence Livermore National Laboratory in Livermore, California, which collaborated with JINR on its synthesis
117	Ts		Tennessee, United States
118	Og		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.

Symbol	Name	Atomic number	Notes	Why not used	Refs
A	Argon	18	A used for Argon until 1957. Current symbol is Ar.	^[4]	^[5]
Ab	Alabamine	85	Discredited claim to discovery of astatine.	^[6]	^[7] ^[8]
Ad	Aldebaranium	70	Former name for ytterbium.
Ah	Anglohelvetium	85	Discredited claim to discovery of astatine.
Ak	Alkalinium	87	Discredited claim to discovery of francium.
Am	Alabamine	85	Discredited claim to discovery of astatine. The symbol Am is now used for americium.
An	Athenium	99	Proposed name for einsteinium.	^[9]
Ao	Ausonium	93	Discredited claim to discovery of neptunium.
At	Austriacum	84	Discredited claim to discovery of polonium. The symbol At is now used for astatine.
Az	Azote	7	Former name for nitrogen.
Bo	Bohemium	93	Discredited claim to discovery of neptunium.
Bo	Boron	5	Current symbol is B.
Bv	Brevium	91	Former name for protactinium-234.
Bz	Berzelium	90	Baskerville wrongly believed berzelium was a new element. Was actually thorium.		^[10]
Cb	Columbium	41	Former name for niobium.
Ch	Chromium	24	Current symbol is Cr.
Cl	Columbium	41	Former name for niobium. The symbol Cl is now used for chlorine.
Cm	Catium	87	Proposed name for francium. The symbol Cm is now used for curium.
Cn	Carolinium	90	Baskerville wrongly believed carolinium to be a new element. Was actually thorium. The symbol Cn is now used for copernicium.
Cp	Cassiopeium	71	Former name for lutetium.
Cp	Copernicium	112	Current symbol is Cn.
Ct	Celtium	72	Discredited claim to discovery of hafnium.
Ct	Centurium	100	Proposed name for fermium.
Cy	Cyclonium	61	Proposed name for promethium.
D	Didymium	59/60	Mixture of the elements praseodymium and neodymium. Mosander wrongly believed didymium to be an element.		^[11]
Da	Davyum	43	Discredited claim to discovery of technetium.
Db	Dubhium	69	Eder wrongly believed dubhium to be a new element. Was actually thulium. The symbol Db is now used for dubnium.
Db	Dubnium	104	Proposed name for rutherfordium. The symbol and name were instead used for element 105.
Dc	Decipium	62	Delafontaine wrongly believed decipium to be a new element. Was actually samarium.
Dc	Dvicaesium	87	Name given by Mendeleev to an as of then undiscovered element. When discovered, francium closely matched the prediction.
De	Denebium	69	Eder wrongly believed denebium to be a new element. Was actually thulium.
Di	Didymium	59/60	Mixture of the elements praseodymium and neodymium. Mosander wrongly believed didymium to be an element.
Do	Dor	85	Discredited claim to discovery of astatine.
Dn	Dubnadium	118	Proposed name for oganesson.
Dp	Decipium	62	Delafontaine wrongly believed decipium to be a new element. Was actually samarium.
Ds	Dysprosium	66	Current symbol is Dy. The symbol Ds is now used for darmstadtium.
Dt	Dvitellurium	84	Name given by Mendeleev to an as of then undiscovered element. When discovered, polonium closely matched the prediction.
E	Einsteinium	99	Current symbol is Es.
E	Erbium	68	Current symbol is Er.
Ea	Ekaaluminium	31	Name given by Mendeleev to an as of then undiscovered element. When discovered, gallium closely matched the prediction.	^[12]
Eb	Ekaboron	21	Name given by Mendeleev to an as of then undiscovered element. When discovered, scandium closely matched the prediction.
Eb	Erebodium	42	Alexander Pringle wrongly believed erebodium to be a new element. Was actually molybdenum.
El	Ekaaluminium	31	Name given by Mendeleev to an as of then undiscovered element. When discovered, gallium closely matched the prediction.
Em	Ekamanganese	43	Name given by Mendeleev to an as of then undiscovered element. When discovered, technetium closely matched the prediction.
Em	Emanation	86	Also 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).
Em	Emanium	89	Alternate name formerly proposed for actinium.
Es	Ekasilicon	32	Name given by Mendeleev to a then undiscovered element. When discovered, germanium closely matched the prediction. The symbol Es is now used for einsteinium.
Es	Esperium	94	Discredited claim to discovery of plutonium. The symbol Es is now used for einsteinium.
Et	Ekatantalum	91	Name given by Mendeleev to an as of then undiscovered element. When discovered, protactinium closely matched the prediction.
Ex	Euxenium	72	Discredited claim to discovery of hafnium.
Fa	Francium	87	Current symbol is Fr.
Fl	Florentium	61	Discredited claim to discovery of promethium. The symbol Fl is now used for flerovium.
Fl	Fluorine	9	Current symbol is F. The symbol Fl is now used for flerovium.
Fr	Florentium	61	Discredited claim to discovery of promethium. The symbol Fr is now used for francium.
G	Glucinium	4	Former name for beryllium.
Gh	Ghiorsium	118	Discredited claim to discovery of oganesson.
Gl	Glucinium	4	Former name for beryllium.
Ha	Hahnium	105	Proposed name for dubnium.
Hn	Hahnium	108	Proposed name for hassium.
Hv	Helvetium	85	Discredited claim to discovery of astatine.
Hy	Mercury	80	Hy from the Greek hydrargyrum for "liquid silver". Current symbol is Hg.
I	Iridium	77	Current symbol is Ir. The symbol I is now used for iodine.
Ic	Incognitium	65	Demarçay wrongly believed incognitium to be a new element. Was actually terbium.
Il	Illinium	61	Discredited claim to discovery of promethium.
Il	Ilmenium	41/73	Mixture of the elements niobium and tantalum. R. Hermann wrongly believed ilmenium to be an element.
Io	Ionium	65	Demarçay wrongly believed ionium to be a new element. Was actually terbium.
J	Jodium	53	Former name for iodine.
Jg	Jargonium	72	Discredited claim to discovery of hafnium.
Jl	Joliotium	105	Proposed name for dubnium.
Jp	Japonium	113	Proposed name for nihonium.
Ka	Potassium	19	Current symbol is K.
Ku	Kurchatovium	104	Proposed name for rutherfordium.
L	Lithium	3	Current symbol is Li.
Lw	Lawrencium	103	Current symbol is Lr.
M	Muriaticum	17	Former name for chlorine.
Ma	Manganese	25	Current symbol is Mn.
Ma	Masurium	43	Disputed claim to discovery of technetium.
Md	Mendelevium	97	Proposed name for berkelium. The symbol and name were later used for element 101.
Ml	Moldavium	87	Discredited claim to discovery of francium.
Ms	Magnesium	12	Current symbol is Mg.
Ms	Masrium	88	Discredited claim to discovery of radium.
Ms	Masurium	43	Disputed claim to discovery of technetium.
Ms	Mosandrium	65	Smith wrongly believed mosandrium to be a new element. Was actually terbium.
Mv	Mendelevium	101	Current symbol is Md.
Ng	Norwegium	72	Discredited claim to discovery of hafnium.
No	Norium	72	Discredited claim to discovery of hafnium. The symbol No is now used for nobelium.
Np	Neptunium	91	Discredited claim to discovery of protactinium. The symbol and name were later used for element 93.		^[13]
Np	Nipponium	43	Discredited claim to discovery of technetium. The symbol Np is now used for neptunium.
Ns	Nielsbohrium	105	Proposed name for dubnium.
Ns	Nielsbohrium	107	Proposed name for bohrium.
Nt	Niton	86	Former name for radon.
Ny	Neoytterbium	70	Former name for ytterbium.
P	Lead	82	Current symbol is Pb. The symbol P is now used for phosphorus.
Pa	Palladium	46	Current symbol is Pd. The symbol Pa is now used for protactinium.
Pe	Pelopium	41	Former name for niobium.
Ph	Phosphorus	15	Current symbol is P.
Pl	Palladium	46	Current symbol is Pd.
Pm	Polymnestum	33	Alexander Pringle wrongly believed polymnestum to be a new element. Was actually arsenic. The symbol Pm is now used for promethium.
Po	Potassium	19	Current symbol is K. The symbol Po is now used for polonium.
Pp	Philippium	67	Delafontaine wrongly believed philippium to be a new element. Was actually holmium.
R	Rhodium	45	Current symbol is Rh. (The symbol is now sometimes used for an alkyl group.)
Rd	Radium	88	Current symbol is Ra.
Rf	Rutherfordium	106	Proposed name for seaborgium. The symbol and name were instead used for element 104.
Ro	Rhodium	45	Current symbol is Rh.
Sa	Samarium	62	Current symbol is Sm.
So	Sodium	11	Current symbol is Na.
Sq	Sequanium	93	Discredited claim to discovery of neptunium.
St	Antimony	51	Current symbol is Sb.
St	Tin	50	Current symbol is Sn.
Tm	Trimanganese	75	Name given by Mendeleev to an as of then undiscovered element. When discovered, rhenium closely matched the prediction. The symbol Tm is now used for thulium.
Tn	Tungsten	74	Current symbol is W.
Tr	Terbium	65	Current symbol is Tb.
Tu	Thulium	69	Current symbol is Tm.
Tu	Tungsten	74	Current symbol is W.
Ur	Uralium	75	Discredited claim to discovery of rhenium.
Ur	Uranium	92	Current symbol is U.
Vc	Victorium	64	Crookes wrongly believed victorium to be a new element. Was actually gadolinium.
Vi	Victorium	64	Crookes wrongly believed victorium to be a new element. Was actually gadolinium.
Vi	Virginium	87	Discredited claim to discovery of francium.
Vm	Virginium	87	Discredited claim to discovery of francium.
Va	Vanadium	23	Current symbol is V.
Wo	Wolfram	74	Former name for tungsten.
X	Xenon	54	Current symbol is Xe. The symbol X is now used for any halogen.
Yt	Yttrium	39	Current symbol is Y.

Systematic chemical symbols

These symbols are based on systematic element names, which are now replaced by trivial (non-systematic) element names and symbols. Data is given in order of: atomic number, systematic symbol, systematic name; trivial symbol, trivial name.

• 101: Unu, unnilunium; Md, mendelevium.
• 102: Unb, unnilbium; No, nobelium.
• 103: Unt, unniltrium; Lr, lawrencium.
• 104: Unq, unnilquadium; Rf, rutherfordium.
• 105: Unp, unnilpentium; Db, dubnium.
• 106: Unh, unnilhexium; Sg, seaborgium.
• 107: Uns, unnilseptium; Bh, bohrium.
• 108: Uno, unniloctium; Hs, hassium.
• 109: Une, unnilennium; Mt, meitnerium.
• 110: Uun, ununnilium; Ds, darmstadtium.
• 111: Uuu, unununium; Rg, roentgenium.
• 112: Uub, ununbium; Cn, copernicium.
• 113: Uut, ununtrium; Nh, nihonium.
• 114: Uuq, ununquadium; Fl, flerovium.
• 115: Uup, ununpentium; Mc, moscovium.
• 116: Uuh, ununhexium; Lv, livermorium.
• 117: Uus, ununseptium; Ts, tennessine.
• 118: Uuo, ununoctium; Og, oganesson.

When elements beyond oganesson (starting with ununennium, Uue, element 119), are discovered; their systematic name and symbol will presumably be superseded by a trivial name and symbol.

Alchemical symbols

See main article: alchemical symbols. The following ideographic symbols were used in alchemy to denote elements known since ancient times. Not included in this list are spurious elements, such as the classical elements fire and water or phlogiston, and substances now known to be compounds. Many more symbols were in at least sporadic use: one early 17th-century alchemical manuscript lists 22 symbols for mercury alone.

Planetary names and symbols for the metals – the seven planets and seven metals known since Classical times in Europe and the Mideast – was ubiquitous in alchemy. The association of what are anachronistically known as planetary metals started breaking down with the discovery of antimony, bismuth and zinc in the 16th century. Alchemists would typically call the metals by their planetary names, e.g. "Saturn" for lead and "Mars" for iron; compounds of tin, iron and silver continued to be called "jovial", "martial" and "lunar"; or "of Jupiter", "of Mars" and "of the moon", through the 17th century. The tradition remains today with the name of the element mercury, where chemists decided the planetary name was preferable to common names like "quicksilver", and in a few archaic terms such as lunar caustic (silver nitrate) and saturnism (lead poisoning).^[14]

Symbol!!Element!!Atomic
number!!Notes

			15	(discovered late)
			16	used by Newton
			25	late; used by Torbern Bergman (1775)
			26	classical planetary metal of Mars
			27	late; used by Bergman
			28	late; used by Bergman (old positional variant of arsenic, previously used for regulus of sulfur)
			30	late; used by Bergman
			29	classical planetary metal of Venus
			33
			47	classical planetary metal of the Moon
			50	classical planetary metal of Jupiter
			51	the newly discovered "eighth metal" was given the symbol for the Earth, which was recognized as a planet by that time
			78	late; used by Bergman et al.: a compound of ☉ gold and ☾ silver
				late; symbol invented for the newly discovered planet Uranus
			79	classical variant
				medieval variant; planetary metal for the Sun
			80	classical planetary metal for Mercury
			82	classical planetary metal for Saturn
			83	used by Newton
				used by Bergman

Daltonian symbols

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 substances now known to be 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.^[15] 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.

Symbol!!rowspan=2

Dalton's name!	Modern name	Atomic number	Notes	Refs
img.					char.
	☉	hydrogen		1	or ⊙	^[16]
		glucine	beryllium	4	alchemical symbol for 'sugar'
	●	carbone, carbon	carbon	6
	⦶	azote	nitrogen/azote	7
	○	oxygen		8	or ◯
	⦷	soda	sodium	11
	⊛	magnesia	magnesium	12	alchemical symbol for magnesia
		alumine	aluminium	13	(4 dots)
		silex	silicon	14		^[17]
		phosphorus		15	(3 radii)
		sulphur		16
		potash	potassium	19	(3 vertical lines)
	⦾	lime	calcium	20	or ◎
		titanium		22	(enclosing circle) Tit⃝
		manganese		25	(enclosing circle) Ma⃝
	Ⓘ	iron		26
	Ⓝ	nickel		28
		cobalt		27	(enclosing circle) Cob⃝
	Ⓒ	copper		29	(black letter in red circle)
	Ⓩ	zinc		30
		arsenic		33	(enclosing circle) Ar⃝
		strontian	strontium	38	(4 ticks)
	⊕︀︀	yttria	yttrium	39	(plus does not touch circle)
		zircone	zirconium	40	(vertical zigzag)
	Ⓢ	silver		47
	Ⓣ	tin		50
		antimony		51	(enclosing circle) An⃝
		barytes	barium	56	(6 ticks)
		cerium		58	(enclosing circle) Ce⃝
		tungsten		74	(enclosing circle) Tu⃝
	Ⓟ	platina	platinum	78	(black letter in red circle)
	Ⓖ	gold		79
		mercury		80	(dotted inside perimeter)
	Ⓛ	lead		82
	Ⓑ	bismuth		83
	Ⓤ	uranium		92

Symbols for named isotopes

The following is a list of isotopes which have been given unique symbols. This is not a list of current systematic symbols (in the Atom form); such a list can instead be found in . The symbols for isotopes of hydrogen, deuterium (D) and tritium (T), are still in use today, as is thoron (Tn) for radon-220 (though not actinon; An usually instead means a generic actinide). 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, d-benzene or CD can be used instead of C[{{sup|2}}H{{sub|6}}].^[18]

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.^[19]

Symbol	Name	Atomic number	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)^[20]
• 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

Exotic atoms:

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

Hazard pictographs are another type of symbols used in chemistry.

See also

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

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

Notes and References

1. IUPAC Provisional Recommendations: IR-3: Elements and Groups of Elements . March 2004 . IUPAC.
2. Web site: Periodic Table – Royal Society of Chemistry. www.rsc.org. en.
3. Web site: Online Etymology Dictionary. etymonline.com. en.
4. Name changed due to a standardization of, modernization of, or update to older formerly-used symbol.
5. Web site: Holden . N. E. . 12 March 2004 . History of the Origin of the Chemical Elements and Their Discoverers . National Nuclear Data Center.
6. Name designated by discredited/disputed claimant.
7. 10.1007/s10699-013-9326-y . The Forgotten Names of Chemical Elements . 2013 . Leal, João P. . . 19 . 2 . 175–183. 254511660 .
8. Web site: Fred Allison. Encyclopedia of Alabama. Lindy. Biggs. Stephen. Knowlton. 3 February 2022.
9. Name proposed prior to discovery/creation of element or prior to official renaming of a placeholder name.
10. Book: Fontani. Marco. Marco Fontani. Costa. Mariagrazia. Orna. Mary Virginia. 2014. The Lost Elements: The Periodic Table's Shadow Side. Oxford University Press. 9780199383344.
11. http://was.chemistryexplained.com/elements/P-T/Praseodymium.html Praseodymium
12. Temporary placeholder name.
13. The Period-Table . 1895 . Rang, F. . The Chemical News and Journal of Physical Science . 72 . 200–201.
14. Maurice Crosland (2004) Historical Studies in the Language of Chemistry
15. Berzelius, Jöns Jakob. "Essay on the Cause of Chemical Proportions, and on Some Circumstances Relating to Them: Together with a Short and Easy Method of Expressing Them." Annals of Philosophy 2, Pp.443–454 (1813); 3, Pp.51–52, 93–106, 244–255, 353–364 (1814); (Subsequently republished in "A Source Book in Chemistry, 1400-1900", eds. Leicester, Henry M. & Herbert S. Klickstein. 1952.)
16. Book: Dalton, John . John Dalton . 1808 . III: On Chemical Synthesis - Section 1: Explanation of the Plates - Plate 4: Elements . A New System of Chemical Philosophy. Part I. . 217–220 . . Printed by S. Russell for R. Bickerstaff, Strand, London.
17. Book: Dalton, John . John Dalton . 1810 . V: Compounds of two Elements - Section 12: Earths - Explanation of Plates - Plate 5: Elements . A New System of Chemical Philosophy. Part II. . 546–548 . . Printed by Russell & Allen for R. Bickerstaff, Strand, London.
18. Web site: IUPAC. Isotopically Modified Compounds. IUPAC. 31 March 2015. SectionH.
19. Morgan. G. T.. 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..
20. Jurczyk. M.. Rajewski. W.. Majchrzycki. W.. Wójcik. G.. 1999-08-30. Mechanically alloyed MmNi₅-type materials for metal hydride electrodes. Journal of Alloys and Compounds. 290. 1–2. 262–266. 10.1016/S0925-8388(99)00202-9.