List of chemical elements

Last updated December 16, 2024

118 chemical elements have been identified and named officially by IUPAC. A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z).^[1]

The definitive visualisation of all 118 elements is the periodic table of the elements, whose history along the principles of the periodic law was one of the founding developments of modern chemistry. It is a tabular arrangement of the elements by their chemical properties that usually uses abbreviated chemical symbols in place of full element names, but the linear list format presented here is also useful. Like the periodic table, the list below organizes the elements by the number of protons in their atoms; it can also be organized by other properties, such as atomic weight, density, and electronegativity. For more detailed information about the origins of element names, see List of chemical element name etymologies.

List

v t e List of chemical elements
Element			Origin of name^[2]^[3]	Group	Period	Block	Standard atomic weight A_r°(E)^[a]	Density ^[b]^[c]	Melting point ^[d]	Boiling point ^[e]	Specific heat capacity ^[f]	Electronegativity ^[g]	Abundance in Earth's crust ^[h]	Origin^[i]	Phase at r.t.^[j]
Atomic number Z	Symbol	Name					(Da)	(⁠g/cm³⁠)	(K)	(K)	(⁠J/g ·K⁠)		(⁠mg/kg⁠)

1	H	Hydrogen	Greek roots hydro- + -gen, 'water-forming'	1	1	s-block	1.0080	0.00008988	14.01	20.28	14.304	2.20	1400	primordial	gas
2	He	Helium	Greek hḗlios 'sun'	18	1	s-block	4.0026	0.0001785	–^[k]	4.22	5.193	–	0.008	primordial	gas
3	Li	Lithium	Greek líthos 'stone'	1	2	s-block	6.94	0.534	453.69	1560	3.582	0.98	20	primordial	solid
4	Be	Beryllium	Beryl, mineral (ultimately after Belur, Karnataka, India?)^[4]	2	2	s-block	9.0122	1.85	1560	2742	1.825	1.57	2.8	primordial	solid
5	B	Boron	Borax, mineral (from Arabic: bawraq, Middle Persian: *bōrag)	13	2	p-block	10.81	2.34	2349	4200	1.026	2.04	10	primordial	solid
6	C	Carbon	Latin carbo 'coal'	14	2	p-block	12.011	2.267	>4000	4300	0.709	2.55	200	primordial	solid
7	N	Nitrogen	Greek nítron + -gen, 'niter-forming'	15	2	p-block	14.007	0.0012506	63.15	77.36	1.04	3.04	19	primordial	gas
8	O	Oxygen	Greek oxy- + -gen, 'acid-forming'	16	2	p-block	15.999	0.001429	54.36	90.20	0.918	3.44	461000	primordial	gas
9	F	Fluorine	Latin fluo 'to flow'	17	2	p-block	18.998	0.001696	53.53	85.03	0.824	3.98	585	primordial	gas
10	Ne	Neon	Greek néon 'new'	18	2	p-block	20.180	0.0009002	24.56	27.07	1.03	–	0.005	primordial	gas
11	Na	Sodium	Coined by Humphry Davy who first isolated it, from English soda (specifically caustic soda), via Italian from Arabic ṣudāʕ 'headache' · Symbol Na, from Neo-Latin natrium , coined from German Natron 'natron'	1	3	s-block	22.990	0.968	370.87	1156	1.228	0.93	23600	primordial	solid
12	Mg	Magnesium	Magnesia region, eastern Thessaly, Greece	2	3	s-block	24.305	1.738	923	1363	1.023	1.31	23300	primordial	solid
13	Al	Aluminium	Alumina, from Latin alumen (gen. aluminis) 'bitter salt, alum'	13	3	p-block	26.982	2.70	933.47	2792	0.897	1.61	82300	primordial	solid
14	Si	Silicon	Latin silex 'flint' (originally silicium)	14	3	p-block	28.085	2.3290	1687	3538	0.705	1.9	282000	primordial	solid
15	P	Phosphorus	Greek phōsphóros 'light-bearing'	15	3	p-block	30.974	1.823	317.30	550	0.769	2.19	1050	primordial	solid
16	S	Sulfur	Latin	16	3	p-block	32.06	2.07	388.36	717.87	0.71	2.58	350	primordial	solid
17	Cl	Chlorine	Greek chlōrós 'greenish yellow'	17	3	p-block	35.45	0.0032	171.6	239.11	0.479	3.16	145	primordial	gas
18	Ar	Argon	Greek argós 'idle' (it is inert)	18	3	p-block	39.95	0.001784	83.80	87.30	0.52	–	3.5	primordial	gas
19	K	Potassium	Neo-Latin potassa 'potash', from pot + ash · Symbol K, from Neo-Latin kalium , from German	1	4	s-block	39.098	0.89	336.53	1032	0.757	0.82	20900	primordial	solid
20	Ca	Calcium	Latin calx 'lime'	2	4	s-block	40.078	1.55	1115	1757	0.647	1.00	41500	primordial	solid
21	Sc	Scandium	Latin Scandia 'Scandinavia'	3	4	d-block	44.956	2.985	1814	3109	0.568	1.36	22	primordial	solid
22	Ti	Titanium	Titans, children of Gaia and Ouranos	4	4	d-block	47.867	4.506	1941	3560	0.523	1.54	5650	primordial	solid
23	V	Vanadium	Vanadis, a name for Norse goddess Freyja	5	4	d-block	50.942	6.11	2183	3680	0.489	1.63	120	primordial	solid
24	Cr	Chromium	Greek chróma 'color'	6	4	d-block	51.996	7.15	2180	2944	0.449	1.66	102	primordial	solid
25	Mn	Manganese	Corrupted from magnesia negra ; see magnesium	7	4	d-block	54.938	7.21	1519	2334	0.479	1.55	950	primordial	solid
26	Fe	Iron	English, from Proto-Celtic īsarnom 'iron', from a root meaning 'blood' · Symbol Fe, from Latin ferrum*	8	4	d-block	55.845	7.874	1811	3134	0.449	1.83	56300	primordial	solid
27	Co	Cobalt	German Kobold , 'goblin'	9	4	d-block	58.933	8.90	1768	3200	0.421	1.88	25	primordial	solid
28	Ni	Nickel	Nickel, a mischievous sprite in German miner mythology	10	4	d-block	58.693	8.908	1728	3186	0.444	1.91	84	primordial	solid
29	Cu	Copper	English, from Latin cuprum , after Cyprus	11	4	d-block	63.546	8.96	1357.77	2835	0.385	1.90	60	primordial	solid
30	Zn	Zinc	Most likely German Zinke , 'prong, tooth', but some suggest Persian sang 'stone'	12	4	d-block	65.38	7.14	692.88	1180	0.388	1.65	70	primordial	solid
31	Ga	Gallium	Latin Gallia 'France'	13	4	p-block	69.723	5.91	302.9146	2673	0.371	1.81	19	primordial	solid
32	Ge	Germanium	Latin Germania 'Germany'	14	4	p-block	72.630	5.323	1211.40	3106	0.32	2.01	1.5	primordial	solid
33	As	Arsenic	Middle English, from Middle French arsenic, from Greek arsenikón 'yellow arsenic' (influenced by arsenikós 'masculine, virile'), from a West Asian wanderword ultimately from Old Persian: *zarniya-ka, lit. 'golden'	15	4	p-block	74.922	5.727	1090^[l]	887	0.329	2.18	1.8	primordial	solid
34	Se	Selenium	Greek selḗnē 'moon'	16	4	p-block	78.971	4.81	453	958	0.321	2.55	0.05	primordial	solid
35	Br	Bromine	Greek brômos 'stench'	17	4	p-block	79.904	3.1028	265.8	332.0	0.474	2.96	2.4	primordial	liquid
36	Kr	Krypton	Greek kryptós 'hidden'	18	4	p-block	83.798	0.003749	115.79	119.93	0.248	3.00	1×10⁻⁴	primordial	gas
37	Rb	Rubidium	Latin rubidus 'deep red'	1	5	s-block	85.468	1.532	312.46	961	0.363	0.82	90	primordial	solid
38	Sr	Strontium	Strontian, a village in Scotland, where it was found	2	5	s-block	87.62	2.64	1050	1655	0.301	0.95	370	primordial	solid
39	Y	Yttrium	Ytterby, Sweden, where it was found; see terbium, erbium, ytterbium	3	5	d-block	88.906	4.472	1799	3609	0.298	1.22	33	primordial	solid
40	Zr	Zirconium	Zircon, mineral, from Persian zargun 'gold-hued'	4	5	d-block	91.224	6.52	2128	4682	0.278	1.33	165	primordial	solid
41	Nb	Niobium	Niobe, daughter of king Tantalus in Greek myth; see tantalum	5	5	d-block	92.906	8.57	2750	5017	0.265	1.6	20	primordial	solid
42	Mo	Molybdenum	Greek molýbdaina 'piece of lead', from mólybdos 'lead', due to confusion with lead ore galena (PbS)	6	5	d-block	95.95	10.28	2896	4912	0.251	2.16	1.2	primordial	solid
43	Tc	Technetium	Greek tekhnētós 'artificial'	7	5	d-block	[97]^[a]	11	2430	4538	–	1.9	~ 3×10⁻⁹	from decay	solid
44	Ru	Ruthenium	Neo-Latin Ruthenia 'Russia'	8	5	d-block	101.07	12.45	2607	4423	0.238	2.2	0.001	primordial	solid
45	Rh	Rhodium	Greek rhodóeis 'rose-colored', from rhódon 'rose'	9	5	d-block	102.91	12.41	2237	3968	0.243	2.28	0.001	primordial	solid
46	Pd	Palladium	Pallas, asteroid, then considered a planet	10	5	d-block	106.42	12.023	1828.05	3236	0.244	2.20	0.015	primordial	solid
47	Ag	Silver	English, from Proto-Germanic · Symbol Ag, from Latin argentum	11	5	d-block	107.87	10.49	1234.93	2435	0.235	1.93	0.075	primordial	solid
48	Cd	Cadmium	Neo-Latin cadmia 'calamine', from King Cadmus, mythic founder of Thebes	12	5	d-block	112.41	8.65	594.22	1040	0.232	1.69	0.159	primordial	solid
49	In	Indium	Latin indicum 'indigo', the blue color named after India and observed in its spectral lines	13	5	p-block	114.82	7.31	429.75	2345	0.233	1.78	0.25	primordial	solid
50	Sn	Tin	English, from Proto-Germanic · Symbol Sn, from Latin stannum	14	5	p-block	118.71	7.265	505.08	2875	0.228	1.96	2.3	primordial	solid
51	Sb	Antimony	Latin antimonium , of unclear origin: folk etymologies suggest Greek antí 'against' + mónos 'alone', or Old French anti-moine 'monk's bane', but could be from or related to Arabic ʾiṯmid 'antimony' · Symbol Sb, from Latin stibium 'stibnite'	15	5	p-block	121.76	6.697	903.78	1860	0.207	2.05	0.2	primordial	solid
52	Te	Tellurium	Latin tellus 'ground, earth'	16	5	p-block	127.60	6.24	722.66	1261	0.202	2.1	0.001	primordial	solid
53	I	Iodine	French iode , from Greek ioeidḗs 'violet'	17	5	p-block	126.90	4.933	386.85	457.4	0.214	2.66	0.45	primordial	solid
54	Xe	Xenon	Greek xénon, neuter of xénos 'strange, foreign'	18	5	p-block	131.29	0.005894	161.4	165.03	0.158	2.60	3×10⁻⁵	primordial	gas
55	Cs	Caesium	Latin caesius 'sky-blue'	1	6	s-block	132.91	1.93	301.59	944	0.242	0.79	3	primordial	solid
56	Ba	Barium	Greek barýs 'heavy'	2	6	s-block	137.33	3.51	1000	2170	0.204	0.89	425	primordial	solid
57	La	Lanthanum	Greek lanthánein 'to lie hidden'	f-block groups	6	f-block	138.91	6.162	1193	3737	0.195	1.1	39	primordial	solid
58	Ce	Cerium	Ceres (dwarf planet), then considered a planet	f-block groups	6	f-block	140.12	6.770	1068	3716	0.192	1.12	66.5	primordial	solid
59	Pr	Praseodymium	Greek prásios dídymos 'green twin'	f-block groups	6	f-block	140.91	6.77	1208	3793	0.193	1.13	9.2	primordial	solid
60	Nd	Neodymium	Greek néos dídymos 'new twin'	f-block groups	6	f-block	144.24	7.01	1297	3347	0.19	1.14	41.5	primordial	solid
61	Pm	Promethium	Prometheus, a Titan	f-block groups	6	f-block	[145]	7.26	1315	3273	–	1.13	2×10⁻¹⁹	from decay	solid
62	Sm	Samarium	Samarskite, a mineral named after V. Samarsky-Bykhovets, Russian mine official	f-block groups	6	f-block	150.36	7.52	1345	2067	0.197	1.17	7.05	primordial	solid
63	Eu	Europium	Europe	f-block groups	6	f-block	151.96	5.244	1099	1802	0.182	1.2	2	primordial	solid
64	Gd	Gadolinium	Gadolinite, a mineral named after Johan Gadolin, Finnish chemist, physicist and mineralogist	f-block groups	6	f-block	157.25	7.90	1585	3546	0.236	1.2	6.2	primordial	solid
65	Tb	Terbium	Ytterby, Sweden, where it was found; see yttrium, erbium, ytterbium	f-block groups	6	f-block	158.93	8.23	1629	3503	0.182	1.2	1.2	primordial	solid
66	Dy	Dysprosium	Greek dysprósitos 'hard to get'	f-block groups	6	f-block	162.50	8.540	1680	2840	0.17	1.22	5.2	primordial	solid
67	Ho	Holmium	Neo-Latin Holmia 'Stockholm'	f-block groups	6	f-block	164.93	8.79	1734	2993	0.165	1.23	1.3	primordial	solid
68	Er	Erbium	Ytterby, where it was found; see yttrium, terbium, ytterbium	f-block groups	6	f-block	167.26	9.066	1802	3141	0.168	1.24	3.5	primordial	solid
69	Tm	Thulium	Thule, the ancient name for an unclear northern location	f-block groups	6	f-block	168.93	9.32	1818	2223	0.16	1.25	0.52	primordial	solid
70	Yb	Ytterbium	Ytterby, where it was found; see yttrium, terbium, erbium	f-block groups	6	f-block	173.05	6.90	1097	1469	0.155	1.1	3.2	primordial	solid
71	Lu	Lutetium	Latin Lutetia 'Paris'	3	6	d-block	174.97	9.841	1925	3675	0.154	1.27	0.8	primordial	solid
72	Hf	Hafnium	Neo-Latin Hafnia 'Copenhagen' (from Danish havn , harbor)	4	6	d-block	178.49	13.31	2506	4876	0.144	1.3	3	primordial	solid
73	Ta	Tantalum	King Tantalus, father of Niobe in Greek myth; see niobium	5	6	d-block	180.95	16.69	3290	5731	0.14	1.5	2	primordial	solid
74	W	Tungsten	Swedish tung sten 'heavy stone' · Symbol W, from Wolfram, from Middle High German wolf-rahm 'wolf's foam' describing the mineral wolframite ^[5]	6	6	d-block	183.84	19.25	3695	6203	0.132	2.36	1.3	primordial	solid
75	Re	Rhenium	Latin Rhenus 'Rhine'	7	6	d-block	186.21	21.02	3459	5869	0.137	1.9	7×10⁻⁴	primordial	solid
76	Os	Osmium	Greek osmḗ 'smell'	8	6	d-block	190.23	22.59	3306	5285	0.13	2.2	0.002	primordial	solid
77	Ir	Iridium	Iris, Greek goddess of rainbow	9	6	d-block	192.22	22.56	2719	4701	0.131	2.20	0.001	primordial	solid
78	Pt	Platinum	Spanish platina 'little silver', from plata 'silver'	10	6	d-block	195.08	21.45	2041.4	4098	0.133	2.28	0.005	primordial	solid
79	Au	Gold	English, from same Proto-Indo-European root as 'yellow' · Symbol Au, from Latin aurum	11	6	d-block	196.97	19.3	1337.33	3129	0.129	2.54	0.004	primordial	solid
80	Hg	Mercury	Mercury, Roman god of commerce, communication, and luck, known for his speed and mobility · Symbol Hg, from Latin hydrargyrum , from Greek hydrárgyros 'water-silver'	12	6	d-block	200.59	13.534	234.43	629.88	0.14	2.00	0.085	primordial	liquid
81	Tl	Thallium	Greek thallós 'green shoot / twig'	13	6	p-block	204.38	11.85	577	1746	0.129	1.62	0.85	primordial	solid
82	Pb	Lead	English, from Proto-Celtic ɸloudom, from a root meaning 'flow' · Symbol Pb, from Latin plumbum*	14	6	p-block	207.2	11.34	600.61	2022	0.129	1.87(2+) 2.33 (4+)	14	primordial	solid
83	Bi	Bismuth	German Wismut , via Latin and Arabic from Greek psimúthion 'white lead'	15	6	p-block	208.98	9.78	544.7	1837	0.122	2.02	0.009	primordial	solid
84	Po	Polonium	Latin Polonia 'Poland', home country of discoverer Marie Curie	16	6	p-block	[209]^[a]	9.196	527	1235	–	2.0	2×10⁻¹⁰	from decay	solid
85	At	Astatine	Greek ástatos 'unstable'; it has no stable isotopes	17	6	p-block	[210]	(8.91–8.95)	575	610	–	2.2	3×10⁻²⁰	from decay	unknown phase
86	Rn	Radon	Radium emanation, originally the name of ²²²Rn	18	6	p-block	[222]	0.00973	202	211.3	0.094	2.2	4×10⁻¹³	from decay	gas
87	Fr	Francium	France, home country of discoverer Marguerite Perey	1	7	s-block	[223]	(2.48)	281	890	–	>0.79^[6]	~ 1×10⁻¹⁸	from decay	unknown phase
88	Ra	Radium	Coined in French by discoverer Marie Curie, from Latin radius 'ray'	2	7	s-block	[226]	5.5	973	2010	0.094	0.9	9×10⁻⁷	from decay	solid
89	Ac	Actinium	Greek aktís 'ray'	f-block groups	7	f-block	[227]	10	1323	3471	0.12	1.1	5.5×10⁻¹⁰	from decay	solid
90	Th	Thorium	Thor, the Norse god of thunder	f-block groups	7	f-block	232.04	11.7	2115	5061	0.113	1.3	9.6	primordial	solid
91	Pa	Protactinium	English prefix proto- (from Greek prôtos 'first, before') + actinium; protactinium decays into actinium.	f-block groups	7	f-block	231.04	15.37	1841	4300	–	1.5	1.4×10⁻⁶	from decay	solid
92	U	Uranium	Uranus, the seventh planet	f-block groups	7	f-block	238.03	19.1	1405.3	4404	0.116	1.38	2.7	primordial	solid
93	Np	Neptunium	Neptune, the eighth planet	f-block groups	7	f-block	[237]	20.45	917	4273	–	1.36	≤ 3×10⁻¹²	from decay	solid
94	Pu	Plutonium	Pluto, dwarf planet, then considered a planet	f-block groups	7	f-block	[244]	19.85	912.5	3501	–	1.28	≤ 3×10⁻¹¹	from decay	solid
95	Am	Americium	Americas, where the element was first synthesized, by analogy with its homolog europium	f-block groups	7	f-block	[243]	12	1449	2880	–	1.13	–	synthetic	solid
96	Cm	Curium	Pierre and Marie Curie, physicists and chemists	f-block groups	7	f-block	[247]	13.51	1613	3383	–	1.28	–	synthetic	solid
97	Bk	Berkelium	Berkeley, California, where it was first synthesized	f-block groups	7	f-block	[247]	14.78	1259	2900	–	1.3	–	synthetic	solid
98	Cf	Californium	California, where it was first synthesized in LBNL	f-block groups	7	f-block	[251]	15.1	1173	(1743)^[b]	–	1.3	–	synthetic	solid
99	Es	Einsteinium	Albert Einstein, German physicist	f-block groups	7	f-block	[252]	8.84	1133	(1269)	–	1.3	–	synthetic	solid
100	Fm	Fermium	Enrico Fermi, Italian physicist	f-block groups	7	f-block	[257]	(9.7)^[b]	(1125)^[7] (1800)^[8]	–	–	1.3	–	synthetic	unknown phase
101	Md	Mendelevium	Dmitri Mendeleev, Russian chemist who proposed the periodic table	f-block groups	7	f-block	[258]	(10.3)	(1100)	–	–	1.3	–	synthetic	unknown phase
102	No	Nobelium	Alfred Nobel, Swedish chemist and engineer	f-block groups	7	f-block	[259]	(9.9)	(1100)	–	–	1.3	–	synthetic	unknown phase
103	Lr	Lawrencium	Ernest Lawrence, American physicist	3	7	d-block	[266]	(14.4)	(1900)	–	–	1.3	–	synthetic	unknown phase
104	Rf	Rutherfordium	Ernest Rutherford, chemist and physicist from New Zealand	4	7	d-block	[267]	(17)	(2400)	(5800)	–	–	–	synthetic	unknown phase
105	Db	Dubnium	Dubna, Russia, where it was discovered in JINR	5	7	d-block	[268]	(21.6)	–	–	–	–	–	synthetic	unknown phase
106	Sg	Seaborgium	Glenn Seaborg, American chemist	6	7	d-block	[267]	(23–24)	–	–	–	–	–	synthetic	unknown phase
107	Bh	Bohrium	Niels Bohr, Danish physicist	7	7	d-block	[270]	(26–27)	–	–	–	–	–	synthetic	unknown phase
108	Hs	Hassium	Neo-Latin Hassia 'Hesse', a state in Germany	8	7	d-block	[271]	(27–29)	–	–	–	–	–	synthetic	unknown phase
109	Mt	Meitnerium	Lise Meitner, Austrian physicist	9	7	d-block	[278]	(27–28)	–	–	–	–	–	synthetic	unknown phase
110	Ds	Darmstadtium	Darmstadt, Germany, where it was first synthesized in the GSI labs	10	7	d-block	[281]	(26–27)	–	–	–	–	–	synthetic	unknown phase
111	Rg	Roentgenium	Wilhelm Röntgen, German physicist	11	7	d-block	[282]	(22–24)	–	–	–	–	–	synthetic	unknown phase
112	Cn	Copernicium	Nicolaus Copernicus, Polish astronomer	12	7	d-block	[285]	(14.0)	(283±11)	(340±10)^[b]	–	–	–	synthetic	unknown phase
113	Nh	Nihonium	Japanese Nihon 'Japan', where it was first synthesized in Riken	13	7	p-block	[286]	(16)	(700)	(1400)	–	–	–	synthetic	unknown phase
114	Fl	Flerovium	Flerov Laboratory of Nuclear Reactions, part of JINR, where it was synthesized; itself named after Georgy Flyorov, Russian physicist	14	7	p-block	[289]	(11.4±0.3)	(284±50)^[b]	–	–	–	–	synthetic	unknown phase
115	Mc	Moscovium	Moscow, Russia, where it was first synthesized in JINR	15	7	p-block	[290]	(13.5)	(700)	(1400)	–	–	–	synthetic	unknown phase
116	Lv	Livermorium	Lawrence Livermore National Laboratory in Livermore, California	16	7	p-block	[293]	(12.9)	(700)	(1100)	–	–	–	synthetic	unknown phase
117	Ts	Tennessine	Tennessee, US, home to ORNL	17	7	p-block	[294]	(7.1–7.3)	(700)	(883)	–	–	–	synthetic	unknown phase
118	Og	Oganesson	Yuri Oganessian, Russian physicist	18	7	p-block	[294]	(7)	(325±15)	(450±10)	–	–	–	synthetic	unknown phase

1 2 3
Standard atomic weight
- '1.0080': abridged value, uncertainty ignored here
- '[97]', [ ] notation: mass number of most stable isotope
1 2 3 4 5 Values in ( ) brackets are predictions
↑ Density ( sources )
↑ Melting point in kelvin (K) ( sources )
↑ Boiling point in kelvin (K) ( sources )
↑ Heat capacity ( sources )
↑ Electronegativity by Pauling ( source )
↑ Abundance of elements in Earth's crust
↑ Primordial (=Earth's origin), from decay, or synthetic
↑ Phase at Standard state (25°C [77°F], 100 kPa)
↑ Melting point: helium does not solidify at a pressure of 1 atmosphere. Helium can only solidify at pressures above 25 atm.
↑ Arsenic sublimes at 1 atmosphere pressure.

Related Research Articles

The atomic number or nuclear charge number of a chemical element is the charge number of its atomic nucleus. For ordinary nuclei composed of protons and neutrons, this is equal to the proton number (n_p) or the number of protons found in the nucleus of every atom of that element. The atomic number can be used to uniquely identify ordinary chemical elements. In an ordinary uncharged atom, the atomic number is also equal to the number of electrons.

Chemistry is the scientific study of the properties and behavior of matter. It is a physical science within the natural sciences that studies the chemical elements that make up matter and compounds made of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during reactions with other substances. Chemistry also addresses the nature of chemical bonds in chemical compounds.

A chemical element is a chemical substance whose atoms all have the same number of protons. The number of protons is called the atomic number of that element. For example, oxygen has an atomic number of 8, meaning each oxygen atom has 8 protons in its nucleus. Atoms of the same element can have different numbers of neutrons in their nuclei, known as isotopes of the element. Two or more atoms can combine to form molecules. Some elements are formed from molecules of identical atoms, e. g. atoms of hydrogen (H) form diatomic molecules (H₂). Chemical compounds are substances made of atoms of different elements; they can have molecular or non-molecular structure. Mixtures are materials containing different chemical substances; that means (in case of molecular substances) that they contain different types of molecules. Atoms of one element can be transformed into atoms of a different element in nuclear reactions, which change an atom's atomic number.

Electronegativity, symbolized as χ, is the tendency for an atom of a given chemical element to attract shared electrons when forming a chemical bond. An atom's electronegativity is affected by both its atomic number and the distance at which its valence electrons reside from the charged nucleus. The higher the associated electronegativity, the more an atom or a substituent group attracts electrons. Electronegativity serves as a simple way to quantitatively estimate the bond energy, and the sign and magnitude of a bond's chemical polarity, which characterizes a bond along the continuous scale from covalent to ionic bonding. The loosely defined term electropositivity is the opposite of electronegativity: it characterizes an element's tendency to donate valence electrons.

The noble gases are the members of group 18 of the periodic table: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn) and, in some cases, oganesson (Og). Under standard conditions, the first six of these elements are odorless, colorless, monatomic gases with very low chemical reactivity and cryogenic boiling points. The properties of the seventh, unstable, element, Og, are uncertain.

Neon is a chemical element; it has the symbol Ne and atomic number 10. It is the second noble gas in the periodic table. Neon is a colorless, odorless, inert monatomic gas under standard conditions, with approximately two-thirds the density of air.

The periodic table, also known as the periodic table of the elements, is an ordered arrangement of the chemical elements into rows ("periods") and columns ("groups"). It is an icon of chemistry and is widely used in physics and other sciences. It is a depiction of the periodic law, which states that when the elements are arranged in order of their atomic numbers an approximate recurrence of their properties is evident. The table is divided into four roughly rectangular areas called blocks. Elements in the same group tend to show similar chemical characteristics.

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.

A period on the periodic table is a row of chemical elements. All elements in a row have the same number of electron shells. Each next element in a period has one more proton and is less metallic than its predecessor. Arranged this way, elements in the same group (column) have similar chemical and physical properties, reflecting the periodic law. For example, the halogens lie in the second-to-last group and share similar properties, such as high reactivity and the tendency to gain one electron to arrive at a noble-gas electronic configuration. As of 2022, a total of 118 elements have been discovered and confirmed.

A period 2 element is one of the chemical elements in the second row of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behavior of the elements as their atomic number increases; a new row is started when chemical behavior begins to repeat, creating columns of elements with similar properties.

A period 1 element is one of the chemical elements in the first row of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate periodic (recurring) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical behaviour begins to repeat, meaning that analog elements fall into the same vertical columns. The first period contains fewer elements than any other row in the table, with only two: hydrogen and helium. This situation can be explained by modern theories of atomic structure. In a quantum mechanical description of atomic structure, this period corresponds to the filling of the 1s orbital. Period 1 elements obey the duet rule in that they need two electrons to complete their valence shell.

Chemistry is the physical science concerned with the composition, structure, and properties of matter, as well as the changes it undergoes during chemical reactions.

The abundance of the chemical elements is a measure of the occurrences of the chemical elements relative to all other elements in a given environment. Abundance is measured in one of three ways: by mass fraction, by mole fraction, or by volume fraction. Volume fraction is a common abundance measure in mixed gases such as planetary atmospheres, and is similar in value to molecular mole fraction for gas mixtures at relatively low densities and pressures, and ideal gas mixtures. Most abundance values in this article are given as mass fractions.

In chemistry, the valence or valency of an atom is a measure of its combining capacity with other atoms when it forms chemical compounds or molecules. Valence is generally understood to be the number of chemical bonds that each atom of a given chemical element typically forms. Double bonds are considered to be two bonds, triple bonds to be three, quadruple bonds to be four, quintuple bonds to be five and sextuple bonds to be six. In most compounds, the valence of hydrogen is 1, of oxygen is 2, of nitrogen is 3, and of carbon is 4. Valence is not to be confused with the related concepts of the coordination number, the oxidation state, or the number of valence electrons for a given atom.

Core electrons are the electrons in an atom that are not valence electrons and do not participate directly in chemical bonding. The nucleus and the core electrons of an atom form the atomic core. Core electrons are tightly bound to the nucleus. Therefore, unlike valence electrons, core electrons play a secondary role in chemical bonding and reactions by screening the positive charge of the atomic nucleus from the valence electrons.

In chemistry, periodic trends are specific patterns present in the periodic table that illustrate different aspects of certain elements when grouped by period and/or group. They were discovered by the Russian chemist Dmitri Mendeleev in 1863. Major periodic trends include atomic radius, ionization energy, electron affinity, electronegativity, nucleophilicity, electrophilicity, valency, nuclear charge, and metallic character. Mendeleev built the foundation of the periodic table. Mendeleev organized the elements based on atomic weight, leaving empty spaces where he believed undiscovered elements would take their places. Mendeleev’s discovery of this trend allowed him to predict the existence and properties of three unknown elements, which were later discovered by other chemists and named gallium, scandium, and germanium. English physicist Henry Moseley discovered that organizing the elements by atomic number instead of atomic weight would naturally group elements with similar properties.

This glossary of chemistry terms is a list of terms and definitions relevant to chemistry, including chemical laws, diagrams and formulae, laboratory tools, glassware, and equipment. Chemistry is a physical science concerned with the composition, structure, and properties of matter, as well as the changes it undergoes during chemical reactions; it features an extensive vocabulary and a significant amount of jargon.

There are currently 118 known chemical elements with a wide range of physical and chemical properties. Amongst this diversity, scientists have found it useful to apply names for various sets of elements that have similar properties, to varying degrees. Many of these sets are formally recognized by the standards body IUPAC.

<span class="mw-page-title-main">Isotope</span> Different atoms of the same element

Isotopes are distinct nuclear species of the same chemical element. They have the same atomic number and position in the periodic table, but different nucleon numbers due to different numbers of neutrons in their nuclei. While all isotopes of a given element have similar chemical properties, they have different atomic masses and physical properties.

References

↑ IUPAC , Compendium of Chemical Terminology , 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) " chemical element ". doi : 10.1351/goldbook.C01022
↑ "Periodic Table – Royal Society of Chemistry". www.rsc.org.
↑ "Online Etymology Dictionary". etymonline.com.
↑ "beryl". Merriam-Webster . Archived from the original on 9 October 2013. Retrieved 27 January 2014.
↑ van der Krogt, Peter. "Wolframium Wolfram Tungsten". Elementymology & Elements Multidict. Archived from the original on 2010-01-23. Retrieved 2010-03-11.
↑ Originally assessed as 0.7 by Pauling but never revised after other elements' electronegativities were updated for precision. Predicted to be higher than that of caesium.
↑ Konings, Rudy J. M.; Beneš, Ondrej. "The Thermodynamic Properties of the 𝑓-Elements and Their Compounds. I. The Lanthanide and Actinide Metals". Journal of Physical and Chemical Reference Data. doi:10.1063/1.3474238.
↑ "Fermium". RSC.

External links

Atoms made thinkable, an interactive visualisation of the elements allowing physical and chemical properties of the elements to be compared

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.

[saw-4] 1 2 3 Standard atomic weight
'1.0080': abridged value, uncertainty ignored here
'[97]', [ ] notation: mass number of most stable isotope

[mwXA] '1.0080': abridged value, uncertainty ignored here

[mwXw] '[97]', [ ] notation: mass number of most stable isotope

[prediction-5] 1 2 3 4 5 Values in ( ) brackets are predictions

[density-6] Density ( sources )

[mp-7] Melting point in kelvin (K) ( sources )

[bp-8] Boiling point in kelvin (K) ( sources )

[heatcapacity-9] Heat capacity ( sources )

[electronegativity-10] Electronegativity by Pauling ( source )

[abundance-11] Abundance of elements in Earth's crust

[origin-12] Primordial (=Earth's origin), from decay, or synthetic

[phase-13] Phase at Standard state (25°C [77°F], 100 kPa)

[helium-14] Melting point: helium does not solidify at a pressure of 1 atmosphere. Helium can only solidify at pressures above 25 atm.

[arsenic-16] Arsenic sublimes at 1 atmosphere pressure.

[1] IUPAC , Compendium of Chemical Terminology , 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) " chemical element ". doi : 10.1351/goldbook.C01022

[2] "Periodic Table – Royal Society of Chemistry". www.rsc.org.

[3] "Online Etymology Dictionary". etymonline.com.

[15] "beryl". Merriam-Webster . Archived from the original on 9 October 2013. Retrieved 27 January 2014.

[sweetums-17] van der Krogt, Peter. "Wolframium Wolfram Tungsten". Elementymology & Elements Multidict. Archived from the original on 2010-01-23. Retrieved 2010-03-11.

[18] Originally assessed as 0.7 by Pauling but never revised after other elements' electronegativities were updated for precision. Predicted to be higher than that of caesium.

[19] Konings, Rudy J. M.; Beneš, Ondrej. "The Thermodynamic Properties of the 𝑓-Elements and Their Compounds. I. The Lanthanide and Actinide Metals". Journal of Physical and Chemical Reference Data. doi:10.1063/1.3474238.

[20] "Fermium". RSC.

[1]

[2]

[3]

[a]

[b]

[c]

[d]

[e]

[f]

[g]

[h]

[i]

[j]

[k]

[4]

[l]

[5]

[6]

[7]

[8]

List of chemical elements

Contents

List

See also

Related Research Articles

References

External links