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	0.000 548
1	1	p	Proton	1.007 276
1	1	n	Neutron	1.008 665	15 mins (free)	b-
1	1	H	Hydrogen	1.007 825		99.985
1	2	D	Deuterium	2.014 102
1	3	T	Tritium	3.016 049	12.3 years	b-
2	3	He	Helium	3.016 030
2	4	He	Helium	4.002 604		~100
2	5	He	Helium	5.012 224	7.6x10-22s	n
3	7	Li	Lithium	7.016 005		92.58
4	8	Be	Beryllium	8.005 308	~6x10-17s	2a
4	9	Be	Beryllium	9.012 186		100
5	11	B	Boron	11.009 305		80.4
6	11	C	Carbon	11.011 43	20.5 mins	b+
6	12	C	Carbon	12.000 000		98.89
6	14	C	Carbon	14.003 242	5570 years	b-
7	13	N	Nitrogen	13.005 739	10.1 mins	b+
7	14	N	Nitrogen	14.003 074		99.63
8	15	O	Oxygen	15.003 066	122 s	b+
8	16	O	Oxygen	15.994 915		99.76
9	19	F	Fluorine	18.998 40		100
10	20	Ne	Neon	19.992 440		90.51
10	22	Ne	Neon	21.991 384		9.22
11	23	Na	Sodium	22.989 773		100
11	24	Na	Sodium	23.990 97	15 hours	b-
12	24	Mg	Magnesium	23.985 045		78.7
13	27	Al	Aluminium	26.981 635
14	28	Si	Silicon	27.976 93
15	31	P	Phosphorus	30.973 763
15	32	P	Phosphorus	31.973 908	14.5 days	b-
16	32	S	Sulphur	31.927 072		95.0
17	35	Cl	Chlorine	34.968 85
18	40	Ar	Argon	39.962 384		95.0
19	39	K	Potassium	38.963 71		93.26
19	40	K	Potassium	39.964 01	1.28x109 years	b-
19	41	K	Potassium	38.963 71
19	42	K	Potassium	41.962 4	12.5 hours	b-
20	40	Ca	Calcium	39.962 59		96.97
20	45	Ca	Calcium	44.956 19	165 days	b-
20	47	Ca	Calcium	46.954 5	4.7 days	b-
21	45	Sc	Scandium	44.995 92
22	48	Ti	Titanium	47.947 95
23	51	V	Vanadium	50.943 98
24	52	Cr	Chromium	51.940 51
25	55	Mn	Manganese	54.938 88
26	54	Fe	Iron	53.939 62		5.82
26	56	Fe	Iron	55.934 93		91.66
26	57	Fe	Iron	56.935 39		2.19
27	59	Co	Cobalt	58.933 19		100
27	60	Co	Cobalt	59.933 81	5.29 years	g
28	58	Ni	Nickel	57.935 34		100
29	63	Cu	Copper	62.929 59		69.1
30	64	Zn	Zinc	63.929 15		48.89
31	69	Ga	Gallium	68.925 7
32	74	Ge	Germanium	73.921 2
33	75	As	Arsenic	74.921
34	80	Se	Selenium	79.916 51
35	79	Br	Bromine	78.918 4		50.54
35	81	Br	Bromine	80.916 3		49.46
35	85	Br	Bromine	84.938		50.54
36	84	Kr	Krypton	83.911 50		49.46
37	85	Rb	Rubidium	84.911 7
38	88	Sr	Strontium	87.905 6		82.6
38	89	Sr	Strontium	88.907	51 days	b-
38	90	Sr	Strontium	84.911 7	28 days	b-
39	89	Y	Yttrium	88.905
40	90	Zr	Zirconium	89.904 3
41	93	Nb	Niobium	92.906 0
42	98	Mo	Molybdenum	97.906
43	99	Tc	Technetium	98.906 *	6 hours	g
43	101	Tc	Technetium	100.9059
44	102	Ru	Ruthenium	101.903 7
45	103	Rh	Rhodium	102.904 8
46	106	Pd	Palladium	105.9036
47	107	Ag	Silver	106.905		54.1
47	111	Ag	Silver	110.905 2	7.5 days	b-
48	114	Cd	Cadmium	113.903 6
49	113	In	Indium	112.904 3
49	115	In	Indium	114.904 1	6x1014 years	b-
50	120	Sn	Tin	119.902
51	121	Sb	Antimony	120.903		57.25
52	122	Te	Tellurium	121.903
53	127	I	Iodine	126.904 35		100
53	128	I	Iodine	127.905 83	25 mins	b-
53	131	I	Iodine	130.906 13	8.04 days	b-
53	132	I	Iodine	131.907 997	138 mins	b-
54	129	Xe	Xenon	128.904 779		26.44
54	132	Xe	Xenon	131.904 16		26.89
54	133	Xe	Xenon	132.905 6	5.3 days	b-
55	133	Cs	Caesium	132.905 1
55	137	Cs	Caesium	136.9068	28 years	b-
56	138	Ba	Barium	137.905 0		71.66
56	139	Ba	Barium	138.908 6	85 mins	b-
56	140	Ba	Barium	139.910 5	12.8 days	b-
57	139	La	Lanthanum	138.906 1		99.91
57	148	La	Lanthanum	147.961
58	140	Ce	Cerium	139.905 3
59	141	Pr	Praseodymium	140.907 4
60	142	Nd	Neodymium	141.907 5
61	147	Pm	Promethium	146.914 9	2.6 years	b-
62	152	Sm	Samarium	151.919 5
63	151	Eu	Europium	150.919 6
64	158	Gd	Gadolinium	157.924 1
65	159	Tb	Terbium	158.925 0
66	164	Dy	Dysprosium	163.938 4
67	165	Ho	Holmium	164.930 3
68	166	Er	Erbium	165.930 4
69	169	Tm	Thulium	168.934
70	174	Yb	Ytterbium	173.939 0
71	175	Lu	Lutetium	174.940 9
72	180	Hf	Hafnium	179.946 8
73	181	Ta	Tantalum	180.940 8
74	184	W	Tungsten	183.951 0
75	185	Re	Rhenium	184.953
76	190	Os	Osmium	189.958 3		26.4
76	192	Os	Osmium	191.161 4		41.0
77	193	Ir	Iridium	192.963 3
78	194	Pt	Platinum	193.962 8		32.9
78	195	Pt	Platinum	194.964 82		33.8
79	197	Au	Gold	196.966 55		100
79	198	Au	Gold	197.968 24	2.7 days	b-
80	200	Hg	Mercury	199.968 34		23.1
80	202	Hg	Mercury	201.970 63		29.8
80	203	Hg	Mercury	202.972 85	47 days	b-
81	205	Tl	Thallium	204.974 46		70.5
82	206	Pb	Lead	205.974 46	47 days	24.1
82	208	Pb	Lead	207.976 44		52.3
82	209	Pb	Lead	208.981 0	3.3 hours	b-
83	209	Bi	Bismuth	208.980 42		100
83	210	Bi	Bismuth	209.984 11	3x106 years	a
84	209	Po	Polonium	208.982 46	200 years	a
84	210	Po	Polonium	209.982 87	138 days	a
85	210	At	Astatine	209.987	8.3 hours	a
86	220	Rn	Radon	220.011 4	52 s	a
86	222	Rn	Radon	222.017	3.83 days	a
87	223	Fr	Francium	223.019 8	22 mins	b-
88	226	Ra	Radium	226.025 36	1600 years	a
88	228	Ra	Radium	228.031 07	1.6x103 years	a
89	227	Ac	Actinium	227.027 81	22 years	a
90	232	Th	Thorium	232.038 21	1.41x1010 years	a
91	231	Pa	Protoactinium	231.035 94	3.4x104 years	a
91	233	Pa	Protoactinium	233.040 11	27.4 days	b-
92	235	U	Uranium	235.043 9	7.1x108 years	a
92	238	U	Uranium	238.050 7	4.5x109 years	a
93	237	Np	Neptunium	237.048 03	2.2x106 years	a
94	242	Pu	Plutonium	242.058 7	3.8x105 years	a
95	243	Am	Americium	243.061 38	8x103 years	a
96	245	Cm	Curium	245.065 34	104 years	a
96	248	Cm	Curium	Fission	5x105 years
97	247	Bk	Berkelium	247.070 18	104 years	a
98	249	Cf	Californium	249.075 70	360 years	a
99	253	Es	Einsteinium	253.084 68	20 days	a
100	250	Fm	Fermium	250.079 48	30 mins	a
101	255	Md	Mendelevium	255.090 6	30 mins	a
102	255	No	Nobelium	255.093 3	3.1 mins	a
103	257	Lw	Lawrencium	257.099 8	~35 s	a

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