Elements table

The following table gives the atomic mass of the most abundant or most stable isotope for each element, together with a few others. The percentage abundance or decay mode and half life are also listed.

Proton number	Nucleon number	Symbol	Name	Atomic mass (u)	Half life	% or decay mode
		e	Electron	0.000548
1	1	p	Proton	1.007276
1	1	n	Neutron	1.008665	15 mins (free)	β-
1	1	H	Hydrogen	1.007825		99.985
1	2	D	Deuterium	2.014102
1	3	T	Tritium	3.016049	12.3 a	β-
2	3	He	Helium	3.016030
2	4	He	Helium	4.002 604		~100
2	5	He	Helium	5.012 224	7.6x10-22s	n
3	7	Li	Lithium	7.016005		92.58
4	8	Be	Beryllium	8.005308	~6x10-17s	2α
4	9	Be	Beryllium	9.012 186		100
5	11	B	Boron	11.009305		80.4
6	11	C	Carbon	11.01143	20.5 mins	β+
6	12	C	Carbon	12.000000		98.89
6	14	C	Carbon	14.003242	5570 a	β-
7	13	N	Nitrogen	13.005739	10.1 mins	β+
7	14	N	Nitrogen	14.003074		99.63
8	15	O	Oxygen	15.003 066	122 s	β+
8	16	O	Oxygen	15.994915		99.76
9	18	F	Fluorine	18.000 93	6486 s	β+ (97%)
9	19	F	Fluorine	18.998 40		100
10	20	Ne	Neon	19.992440		90.51
10	22	Ne	Neon	21.991384		9.22
11	23	Na	Sodium	22.989773		100
11	24	Na	Sodium	23.99097	15 hours	β-
12	24	Mg	Magnesium	23.985045		78.7
13	27	Al	Aluminium	26.981 635
14	28	Si	Silicon	27.97693
15	31	P	Phosphorus	30.973763
15	32	P	Phosphorus	31.973908	14.5 days	β-
16	32	S	Sulphur	31.927072		95.0
17	35	Cl	Chlorine	34.96885
18	40	Ar	Argon	39.962 384		95.0
19	39	K	Potassium	38.96371		93.26
19	40	K	Potassium	39.96401	1.3x109 a	β-
19	41	K	Potassium	38.96371
19	42	K	Potassium	41.9624	12.5 hours	β-
20	40	Ca	Calcium	39.96259		96.97
20	45	Ca	Calcium	44.95619	165 days	β-
20	47	Ca	Calcium	46.9545	4.7 days	β-
21	45	Sc	Scandium	44.99592
22	48	Ti	Titanium	47.94795
23	51	V	Vanadium	50.94398
24	52	Cr	Chromium	51.94051
25	55	Mn	Manganese	54.938 88
26	54	Fe	Iron	53.93962		5.82
26	56	Fe	Iron	55.934 93		91.66
26	57	Fe	Iron	56.93539		2.19
27	59	Co	Cobalt	58.933 19		100
27	60	Co	Cobalt	59.93381	5.29 a	g
28	58	Ni	Nickel	57.93534		100
29	63	Cu	Copper	62.929 59		69.1
30	64	Zn	Zinc	63.92915		48.89
31	69	Ga	Gallium	68.9257
32	74	Ge	Germanium	73.9212
33	75	As	Arsenic	74.921
34	80	Se	Selenium	79.91651
35	79	Br	Bromine	78.9184		50.54
35	81	Br	Bromine	80.9163		49.46
35	85	Br	Bromine	84.938		50.54
36	84	Kr	Krypton	83.91150		49.46
37	85	Rb	Rubidium	84.911 7
38	88	Sr	Strontium	87.9056		82.6
38	89	Sr	Strontium	88.907	51 days	β-
38	90	Sr	Strontium	84.9117	28 days	β-
39	89	Y	Yttrium	88.905
40	90	Zr	Zirconium	89.9043
41	93	Nb	Niobium	92.9060
42	98	Mo	Molybdenum	97.906
43	99	Tc	Technetium	98.906*	6 hours	γ
43	101	Tc	Technetium	100.9059
44	102	Ru	Ruthenium	101.9037
45	103	Rh	Rhodium	102.9048
46	106	Pd	Palladium	105.9036
47	107	Ag	Silver	106.905		54.1
47	111	Ag	Silver	110.9052	7.5 days	β-
48	114	Cd	Cadmium	113.9036
49	113	In	Indium	112.9043
49	115	In	Indium	114.9041	6x1014 a	β-
50	120	Sn	Tin	119.902
51	121	Sb	Antimony	120.903		57.25
52	122	Te	Tellurium	121.903
53	127	I	Iodine	126.90435		100
53	128	I	Iodine	127.90583	25 mins	β-
53	131	I	Iodine	130.906 13	8.04 days	β-
53	132	I	Iodine	131.907997	138 mins	β-
54	129	Xe	Xenon	128.904779		26.44
54	132	Xe	Xenon	131.90416		26.89
54	133	Xe	Xenon	132.9056	5.3 days	β-
55	133	Cs	Caesium	132.905 1
55	137	Cs	Caesium	136.9068	28 a	β-
56	138	Ba	Barium	137.9050		71.66
56	139	Ba	Barium	138.908 6	85 mins	β-
56	140	Ba	Barium	139.910 5	12.8 days	β-
57	139	La	Lanthanum	138.9061		99.91
57	148	La	Lanthanum	147.961
58	140	Ce	Cerium	139.9053
59	141	Pr	Praseodymium	140.9074
60	142	Nd	Neodymium	141.9075
61	147	Pm	Promethium	146.9149	2.6 a	β-
62	152	Sm	Samarium	151.9195
63	151	Eu	Europium	150.919 6
64	158	Gd	Gadolinium	157.9241
65	159	Tb	Terbium	158.925 0
66	164	Dy	Dysprosium	163.9384
67	165	Ho	Holmium	164.9303
68	166	Er	Erbium	165.9304
69	169	Tm	Thulium	168.934
70	174	Yb	Ytterbium	173.9390
71	175	Lu	Lutetium	174.940 9
72	180	Hf	Hafnium	179.9468
73	181	Ta	Tantalum	180.9408
74	184	W	Tungsten	183.9510
75	185	Re	Rhenium	184.953
76	190	Os	Osmium	189.958 3		26.4
76	192	Os	Osmium	191.1614		41.0
77	193	Ir	Iridium	192.963 3
78	194	Pt	Platinum	193.9628		32.9
78	195	Pt	Platinum	194.96482		33.8
79	197	Au	Gold	196.966 55		100
79	198	Au	Gold	197.96824	2.7 days	β-
80	200	Hg	Mercury	199.96834		23.1
80	202	Hg	Mercury	201.97063		29.8
80	203	Hg	Mercury	202.97285	47 days	β-
81	205	Tl	Thallium	204.97446		70.5
82	206	Pb	Lead	205.97446	47 days	24.1
82	208	Pb	Lead	207.97644		52.3
82	209	Pb	Lead	208.9810	3.3 hours	β-
83	209	Bi	Bismuth	208.98042		100
83	210	Bi	Bismuth	209.98411	3x106 a	α
84	209	Po	Polonium	208.98246	200 a	α
84	210	Po	Polonium	209.98287	138 days	α
85	210	At	Astatine	209.987	8.3 hours	α
86	220	Rn	Radon	220.0114	52 s	α
86	222	Rn	Radon	222.017	3.83 days	α
87	223	Fr	Francium	223.019 8	22 mins	β-
88	226	Ra	Radium	226.02536	1600 a	α
88	228	Ra	Radium	228.031 07	1.6x103 a	α
89	227	Ac	Actinium	227.02781	22 a	α
90	232	Th	Thorium	232.03821	1.4x1010 a	α
91	231	Pa	Protoactinium	231.03594	3.4x104 a	α
91	233	Pa	Protoactinium	233.04011	27.4 days	β-
92	235	U	Uranium	235.0439	7.1x108 a	α
92	238	U	Uranium	238.0507	4.5x109 a	α
93	237	Np	Neptunium	237.04803	2.2x106 a	α
94	242	Pu	Plutonium	242.0587	3.8x105 a	α
95	243	Am	Americium	243.06138	8x103 a	α
96	245	Cm	Curium	245.065 34	104 a	α
96	248	Cm	Curium	Fission	5x105 a
97	247	Bk	Berkelium	247.07018	104 a	α
98	249	Cf	Californium	249.075 70	360 a	α
99	253	Es	Einsteinium	253.08468	20 days	α
100	250	Fm	Fermium	250.079 48	30 mins	α
101	255	Md	Mendelevium	255.090 6	30 mins	α
102	255	No	Nobelium	255.0933	3.1 mins	α
103	257	Lw	Lawrencium	257.099 8	~35 s	α

For an alphabetical list of the elements please see: Table of elements (alphabetical)