Contents

Atomic Masses

Appendix A Atomic Masses

Atomic Number, Z	Name	Atomic Mass Number, A	Symbol	Atomic Mass (u)	Percent Abundance or Decay Mode	Half-life, t_1/2
0	neutron	1	$n n size 12{n} {}$	1.008 665	$β^{-} β^{-} size 12{β rSup { size 8{ - {}} } } {}$	10.37 min
1	Hydrogen	1	$1 H 1 H size 12{rSup { size 8{ 1 {}} }H} {}$	1.007 825	99.985%
	Deuterium	2	$2 H or D 2 H or D size 12{rSup { size 8{ 2 {}} }H or D} {}$	2.014 102	0.015%
	Tritium	3	$3 H or T 3 H or T size 12{rSup { size 8{ 3 {}} }H or T} {}$	3.016 050	$β^{-} β^{-} size 12{β rSup { size 8{ - {}} } } {}$	12.33 y
2	Helium	3	$3 He 3 He size 12{rSup { size 8{ 3 {}} }He} {}$	3.016 030	$1 . 38 \times 10^{- 4} % 1 . 38 \times 10^{- 4} % size 12{1 "." "38" times "10" rSup { size 8{ - 4} } %} {}$
		4	$4 He 4 He size 12{rSup { size 8{ 4 {}} }He} {}$	4.002 603	$≈100% ≈100% size 12{ approx "100"%} {}$
3	Lithium	6	$6 Li 6 Li size 12{rSup { size 8{ 6 {}} }Li} {}$	6.015 121	7.5%
		7	$7 Li 7 Li size 12{rSup { size 8{ 7 {}} }Li} {}$	7.016 003	92.5%
4	Beryllium	7	$7 Be 7 Be size 12{rSup { size 8{ 7 {}} }Be} {}$	7.016 928	EC	53.29 d
		9	$9 Be 9 Be size 12{rSup { size 8{ 9 {}} }Be} {}$	9.012 182	100%
5	Boron	10	$10 B 10 B size 12{rSup { size 8{ 10 {}} }B} {}$	10.012 937	19.9%
		11	$11 B 11 B size 12{rSup { size 8{ 11 {}} }B} {}$	11.009 305	80.1%
6	Carbon	11	$11 C 11 C size 12{rSup { size 8{ 11 {}} }C} {}$	11.011 432	EC, $β^{+} β^{+} size 12{β rSup { size 8{+{}} } } {}$
		12	$12 C 12 C size 12{rSup { size 8{ 6 {}} }Li} {}$	12.000 000	98.90%
		13	$13 C 13 C size 12{rSup { size 8{ 13 {}} }C} {}$	13.003 355	1.10%
		14	$14 C 14 C size 12{rSup { size 8{ 14 {}} }C} {}$	14.003 241	$β^{-} β^{-} size 12{β rSup { size 8{ - {}} } } {}$	5730 y
7	Nitrogen	13	$13 N 13 N size 12{rSup { size 8{ 13 {}} }N} {}$	13.005 738	$β^{+} β^{+} size 12{β rSup { size 8{+{}} } } {}$	9.96 min
		14	$14 N 14 N size 12{rSup { size 8{ 14 {}} }N} {}$	14.003 074	99.63%
		15	$15 N 15 N size 12{rSup { size 8{ 15 {}} }N} {}$	15.000 108	0.37%
8	Oxygen	15	$15 O 15 O size 12{rSup { size 8{ 15 {}} }O} {}$	15.003 065	EC, $β^{+} β^{+} size 12{β rSup { size 8{+{}} } } {}$	122 s
		16	$16 O 16 O size 12{rSup { size 8{ 6 {}} }Li} {}$	15.994 915	99.76%
		18	$18 O 18 O size 12{rSup { size 8{ 18 {}} }O} {}$	17.999 160	0.200%
9	Fluorine	18	$18 F 18 F size 12{rSup { size 8{ 18 {}} }F} {}$	18.000 937	EC, $β^{+} β^{+} size 12{β rSup { size 8{+{}} } } {}$	1.83 h
		19	$19 F 19 F size 12{rSup { size 8{ 6 {}} }Li} {}$	18.998 403	100%
10	Neon	20	$20 Ne 20 Ne size 12{rSup { size 8{ 20 {}} }Ne} {}$	19.992 435	90.51%
		22	$22 Ne 22 Ne size 12{rSup { size 8{ 22 {}} }Ne} {}$	21.991 383	9.22%
11	Sodium	22	$22 Na 22 Na size 12{rSup { size 8{ 6 {}} }Li} {}$	21.994 434	$β^{+} β^{+} size 12{β rSup { size 8{ - {}} } } {}$	2.602 y
		23	$23 Na 23 Na size 12{rSup { size 8{ 23 {}} }Na} {}$	22.989 767	100%
		24	$24 Na 24 Na size 12{rSup { size 8{ 24 {}} }Na} {}$	23.990 961	$β^{-} β^{-} size 12{β rSup { size 8{ - {}} } } {}$	14.96 h
12	Magnesium	24	$24 Mg 24 Mg size 12{rSup { size 8{ 24 {}} }Mg} {}$	23.985 042	78.99%
13	Aluminum	27	$27 Al 27 Al size 12{rSup { size 8{ 27 {}} }Al} {}$	26.981 539	100%
14	Silicon	28	$28 Si 28 Si size 12{rSup { size 8{ 28 {}} }Si} {}$	27.976 927	92.23%	2.62h
		31	$31 Si 31 Si size 12{rSup { size 8{ 31 {}} }Si} {}$	30.975 362	$β^{-} β^{-} size 12{β rSup { size 8{ - {}} } } {}$
15	Phosphorus	31	$31 P 31 P size 12{rSup { size 8{ 31 {}} }P} {}$	30.973 762	100%
		32	$32 P 32 P size 12{rSup { size 8{ 6 {}} }Li} {}$	31.973 907	$β^{-} β^{-} size 12{β rSup { size 8{ - {}} } } {}$	14.28 d
16	Sulfur	32	$32 S 32 S size 12{rSup { size 8{ 6 {}} }Li} {}$	31.972 070	95.02%
		35	$35 S 35 S size 12{rSup { size 8{ 35 {}} }S} {}$	34.969 031	$β^{-} β^{-} size 12{β rSup { size 8{ - {}} } } {}$	87.4 d
17	Chlorine	35	$35 Cl 35 Cl size 12{rSup { size 8{ 35 {}} }Cl} {}$	34.968 852	75.77%
		37	$37 Cl 37 Cl size 12{rSup { size 8{ 35 {}} }Cl} {}$	36.965 903	24.23%
18	Argon	40	$40 Ar 40 Ar size 12{rSup { size 8{ 40 {}} }Ar} {}$	39.962 384	99.60%
19	Potassium	39	$39 K 39 K size 12{rSup { size 8{ 39 {}} }K} {}$	38.963 707	93.26%
		40	$40 K 40 K size 12{rSup { size 8{ 40 {}} }K} {}$	39.963 999	0.0117%, EC, $β^{-} β^{-} size 12{β rSup { size 8{ - {}} } } {}$	$1 . 28 \times 10^{9} y 1 . 28 \times 10^{9} y size 12{1 "." "28" times "10" rSup { size 7{9} } y} {}$
20	Calcium	40	$40 Ca 40 Ca size 12{rSup { size 8{ 40 {}} }Ca} {}$	39.962 591	96.94%
21	Scandium	45	$45 Sc 45 Sc size 12{rSup { size 8{ 45 {}} }Sc} {}$	44.955 910	100%
22	Titanium	48	$48 Ti 48 Ti size 12{rSup { size 8{ 48 {}} }Ti} {}$	47.947 947	73.8%
23	Vanadium	51	$51 V 51 V size 12{rSup { size 8{ 51 {}} }V} {}$	50.943 962	99.75%
24	Chromium	52	$52 Cr 52 Cr size 12{rSup { size 8{ 52 {}} }Cr} {}$	51.940 509	83.79%
25	Manganese	55	$55 Mn 55 Mn size 12{rSup { size 8{ 55 {}} }Mn} {}$	54.938 047	100%
26	Iron	56	$56 Fe 56 Fe size 12{rSup { size 8{ 56 {}} }Fe} {}$	55.934 939	91.72%
27	Cobalt	59	$59 Co 59 Co size 12{rSup { size 8{ 59 {}} }Co} {}$	58.933 198	100%
		60	$60 Co 60 Co size 12{rSup { size 8{ 60 {}} }Co} {}$	59.933 819	$β^{-} β^{-} size 12{β rSup { size 8{ - {}} } } {}$	5.271 y
28	Nickel	58	$58 Ni 58 Ni size 12{rSup { size 8{ 58 {}} }Ni} {}$	57.935 346	68.27%
		60	$60 Ni 60 Ni size 12{rSup { size 8{ 60 {}} }Ni} {}$	59.930 788	26.10%
29	Copper	63	$63 Cu 63 Cu size 12{rSup { size 8{ 63 {}} }Cu} {}$	62.939 598	69.17%
		65	$65 Cu 65 Cu size 12{rSup { size 8{ 65 {}} }Cu} {}$	64.927 793	30.83%
30	Zinc	64	$64 Zn 64 Zn size 12{rSup { size 8{ 64 {}} }Zn} {}$	63.929 145	48.6%
		66	$66 Zn 66 Zn size 12{rSup { size 8{ 66 {}} }Zn} {}$	65.926 034	27.9%
31	Gallium	69	$69 Ga 69 Ga size 12{rSup { size 8{ 69 {}} }Ga} {}$	68.925 580	60.1%
32	Germanium	72	$72 Ge 72 Ge size 12{rSup { size 8{ 72 {}} }Ge} {}$	71.922 079	27.4%
		74	$74 Ge 74 Ge size 12{rSup { size 8{ 74 {}} }Ge} {}$	73.921 177	36.5%
33	Arsenic	75	$75 As 75 As size 12{rSup { size 8{ 75 {}} }As} {}$	74.921 594	100%
34	Selenium	80	$80 Se 80 Se size 12{rSup { size 8{ 80 {}} }Se} {}$	79.916 520	49.7%
35	Bromine	79	$79 Br 79 Br size 12{rSup { size 8{ 79 {}} }Br} {}$	78.918 336	50.69%
36	Krypton	84	$84 Kr 84 Kr size 12{rSup { size 8{ 84 {}} }Kr} {}$	83.911 507	57.0%
37	Rubidium	85	$85 Rb 85 Rb size 12{rSup { size 8{ 85 {}} }Rb} {}$	84.911 794	72.17%
38	Strontium	86	$86 Sr 86 Sr size 12{rSup { size 8{ 86 {}} }Sr} {}$	85.909 267	9.86%
		88	$88 Sr 88 Sr size 12{rSup { size 8{ 88 {}} }Sr} {}$	87.905 619	82.58%
		90	$90 Sr 90 Sr size 12{rSup { size 8{ 90 {}} }Sr} {}$	89.907 738	$β^{-} β^{-} size 12{β rSup { size 8{ - {}} } } {}$	28.8 y
39	Yttrium	89	$89 Y 89 Y size 12{rSup { size 8{ 89 {}} }Y} {}$	88.905 849	100%
		90	$90 Y 90 Y size 12{rSup { size 8{ 90 {}} }Y} {}$	89.907 152	$β^{-} β^{-} size 12{β rSup { size 8{ - {}} } } {}$	64.1 h
40	Zirconium	90	$90 Zr 90 Zr size 12{rSup { size 8{ 90 {}} }Zr} {}$	89.904 703	51.45%
41	Niobium	93	$93 Nb 93 Nb size 12{rSup { size 8{ 93 {}} }Nb} {}$	92.906 377	100%
42	Molybdenum	98	$98 Mo 98 Mo size 12{rSup { size 8{ 98 {}} }Mo} {}$	97.905 406	24.13%
43	Technetium	98	$98 Tc 98 Tc size 12{rSup { size 8{ 98 {}} }Tc} {}$	97.907 215	$β^{-} β^{-} size 12{β rSup { size 8{ - {}} } } {}$	$4 . 2 \times 10^{6} y 4 . 2 \times 10^{6} y size 12{4 "." 2 times "10" rSup { size 8{6} } y} {}$
44	Ruthenium	102	$102 Ru 102 Ru size 12{rSup { size 8{ 102 {}} }Ru} {}$	101.904 348	31.6%
45	Rhodium	103	$103 Rh 103 Rh size 12{rSup { size 8{ 103 {}} }Rh} {}$	102.905 500	100%
46	Palladium	106	$106 Pd 106 Pd size 12{rSup { size 8{ 106 {}} }Pd} {}$	105.903 478	27.33%
47	Silver	107	$107 Ag 107 Ag size 12{rSup { size 8{ 107 {}} }Ag} {}$	106.905 092	51.84%
		109	$109 Ag 109 Ag size 12{rSup { size 8{ 109 {}} }Ag} {}$	108.904 757	48.16%
48	Cadmium	114	$114 Cd 114 Cd size 12{rSup { size 8{ 114 {}} }Cd} {}$	113.903 357	28.73%
49	Indium	115	$115 In 115 In size 12{rSup { size 8{ 115 {}} }In} {}$	114.903 880	95.7%, $β^{-} β^{-} size 12{β rSup { size 8{ - {}} } } {}$	$4 . 4 \times 10^{14} y 4 . 4 \times 10^{14} y size 12{4 "." 4 times "10" rSup { size 8{"14"} } y} {}$
50	Tin	120	$120 Sn 120 Sn size 12{rSup { size 8{ 120 {}} }Sn} {}$	119.902 200	32.59%
51	Antimony	121	$121 Sb 121 Sb size 12{rSup { size 8{ 121 {}} }Sb} {}$	120.903 821	57.3%
52	Tellurium	130	$130 Te 130 Te size 12{rSup { size 8{ 130 {}} }Te} {}$	129.906 229	33.8%, $β^{-} β^{-} size 12{β rSup { size 8{ - {}} } } {}$	$2 . 5 \times 10^{21} y 2 . 5 \times 10^{21} y size 12{2 "." 5 times "10" rSup { size 8{"21"} } y} {}$
53	Iodine	127	$127 I 127 I size 12{rSup { size 8{ 127 {}} }I} {}$	126.904 473	100%
		131	$131 I 131 I size 12{rSup { size 8{ 131 {}} }I} {}$	130.906 114	$β^{-} β^{-} size 12{β rSup { size 8{ - {}} } } {}$	8.040 d
54	Xenon	132	$132 Xe 132 Xe size 12{rSup { size 8{ 132 {}} }Xe} {}$	131.904 144	26.9%
		136	$136 Xe 136 Xe size 12{rSup { size 8{ 136 {}} }Xe} {}$	135.907 214	8.9%
55	Cesium	133	$133 Cs 133 Cs size 12{rSup { size 8{ 133 {}} }Cs} {}$	132.905 429	100%
		134	$134 Cs 134 Cs size 12{rSup { size 8{ 134 {}} }Cs} {}$	133.906 696	EC, $β^{-} β^{-} size 12{β rSup { size 8{ - {}} } } {}$	2.06 y
56	Barium	137	$137 Ba 137 Ba size 12{rSup { size 8{ 137 {}} }Ba} {}$	136.905 812	11.23%
		138	$138 Ba 138 Ba size 12{rSup { size 8{ 138 {}} }Ba} {}$	137.905 232	71.70%
57	Lanthanum	139	$139 La 139 La size 12{rSup { size 8{ 139 {}} }La} {}$	138.906 346	99.91%
58	Cerium	140	$140 Ce 140 Ce size 12{rSup { size 8{ 140 {}} }Ce} {}$	139.905 433	88.48%
59	Praseodymium	141	$141 Pr 141 Pr size 12{rSup { size 8{ 141 {}} }Pr} {}$	140.907 647	100%
60	Neodymium	142	$142 Nd 142 Nd size 12{rSup { size 8{ 142 {}} }Nd} {}$	141.907 719	27.13%
61	Promethium	145	$145 Pm 145 Pm size 12{rSup { size 8{ 145 {}} }Pm} {}$	144.912 743	EC, $α α size 12{α} {}$	17.7 y
62	Samarium	152	$152 Sm 152 Sm size 12{rSup { size 8{ 152 {}} }Sm} {}$	151.919 729	26.7%
63	Europium	153	$153 Eu 153 Eu size 12{rSup { size 8{ 153 {}} }Eu} {}$	152.921 225	52.2%
64	Gadolinium	158	$158 Gd 158 Gd size 12{rSup { size 8{ 158 {}} }Gd} {}$	157.924 099	24.84%
65	Terbium	159	$159 Tb 159 Tb size 12{rSup { size 8{ 159 {}} }Tb} {}$	158.925 342	100%
66	Dysprosium	164	$164 Dy 164 Dy size 12{rSup { size 8{ 164 {}} }Dy} {}$	163.929 171	28.2%
67	Holmium	165	$165 Ho 165 Ho size 12{rSup { size 8{ 165 {}} }Ho} {}$	164.930 319	100%
68	Erbium	166	$166 Er 166 Er size 12{rSup { size 8{ 166 {}} }Er} {}$	165.930 290	33.6%
69	Thulium	169	$169 Tm 169 Tm size 12{rSup { size 8{ 169 {}} }Tm} {}$	168.934 212	100%
70	Ytterbium	174	$174 Yb 174 Yb size 12{rSup { size 8{ 174 {}} }Yb} {}$	173.938 859	31.8%
71	Lutecium	175	$175 Lu 175 Lu size 12{rSup { size 8{ 174 {}} }Yb} {}$	174.940 770	97.41%
72	Hafnium	180	$180 Hf 180 Hf size 12{rSup { size 8{ 180 {}} }Hf} {}$	179.946 545	35.10%
73	Tantalum	181	$181 Ta 181 Ta size 12{rSup { size 8{ 181 {}} }Ta} {}$	180.947 992	99.98%
74	Tungsten	184	$184 W 184 W size 12{rSup { size 8{ 184 {}} }W} {}$	183.950 928	30.67%
75	Rhenium	187	$187 Re 187 Re size 12{rSup { size 8{ 187 {}} }Re} {}$	186.955 744	62.6%, $β^{-} β^{-} size 12{β rSup { size 8{ - {}} } } {}$	$4 . 6 \times 10^{10} y 4 . 6 \times 10^{10} y size 12{4 "." 6 times "10" rSup { size 8{"10"} } y} {}$
76	Osmium	191	$191 Os 191 Os size 12{rSup { size 8{ 191 {}} }Os} {}$	190.960 920	$β^{-} β^{-} size 12{β rSup { size 8{ - {}} } } {}$	15.4 d
		192	$192 Os 192 Os size 12{rSup { size 8{ 192 {}} }Os} {}$	191.961 467	41.0%
77	Iridium	191	$191 Ir 191 Ir size 12{rSup { size 8{ 191 {}} }Ir} {}$	190.960 584	37.3%
		193	$193 Ir 193 Ir size 12{rSup { size 8{ 193 {}} }Ir} {}$	192.962 917	62.7%
78	Platinum	195	$195 Pt 195 Pt size 12{rSup { size 8{ 195 {}} }Pt} {}$	194.964 766	33.8%
79	Gold	197	$197 Au 197 Au size 12{rSup { size 8{ 197 {}} }Au} {}$	196.966 543	100%
		198	$198 Au 198 Au size 12{rSup { size 8{ 198 {}} }Au} {}$	197.968 217	$β^{-} β^{-} size 12{β rSup { size 8{ - {}} } } {}$	2.696 d
80	Mercury	199	$199 Hg 199 Hg size 12{rSup { size 8{ 199 {}} }Hg} {}$	198.968 253	16.87%
		202	$202 Hg 202 Hg size 12{rSup { size 8{ 202 {}} }Hg} {}$	201.970 617	29.86%
81	Thallium	205	$205 Tl 205 Tl size 12{rSup { size 8{ 205{}} }Tl} {}$	204.974 401	70.48%
82	Lead	206	$206 Pb 206 Pb size 12{rSup { size 8{ 206{}} }Pb} {}$	205.974 440	24.1%
		207	$207 Pb 207 Pb size 12{rSup { size 8{ 207{}} }Pb} {}$	206.975 872	22.1%
		208	$208 Pb 208 Pb size 12{rSup { size 8{ 208{}} }Pb} {}$	207.976 627	52.4%
		210	$210 Pb 210 Pb size 12{rSup { size 8{ 210{}} }Pb} {}$	209.984 163	$α, β^{-} α, size 12{α,β rSup { size 8{ - {}} } } {}$	22.3 y
		211	$211 Pb 211 Pb size 12{rSup { size 8{ 211{}} }Pb} {}$	210.988 735	$β^{-} β^{-} size 12{β rSup { size 8{ - {}} } } {}$	36.1 min
		212	$212 Pb 212 Pb size 12{rSup { size 8{ 212{}} }Pb} {}$	211.991 871	$β^{-} β^{-} size 12{β rSup { size 8{ - {}} } } {}$	10.64 h
83	Bismuth	209	$209 Bi 209 Bi size 12{rSup { size 8{ 209{}} }Bi} {}$	208.980 374	100%
		211	$211 Bi 211 Bi size 12{rSup { size 8{ 211{}} }Bi} {}$	210.987 255	$α, β^{-} α, size 12{α,β rSup { size 8{ - {}} } } {}$	2.14 min
84	Polonium	210	$210 Po 210 Po size 12{rSup { size 8{ 210{}} }Po} {}$	209.982 848	$α α size 12{α} {}$	138.38 d
85	Astatine	218	$218 At 218 At size 12{rSup { size 8{ 218{}} }At} {}$	218.008 684	$α, β^{-} α, size 12{α,β rSup { size 8{ - {}} } } {}$	1.6 s
86	Radon	222	$222 Rn 222 Rn size 12{rSup { size 8{ 222{}} }Rn} {}$	222.017 570	$α α size 12{α} {}$	3.82 d
87	Francium	223	$223 Fr 223 Fr size 12{rSup { size 8{ 223{}} }Fr} {}$	223.019 733	$α, β^{-} α, size 12{α,β rSup { size 8{ - {}} } } {}$	21.8 min
88	Radium	226	$226 Ra 226 Ra size 12{rSup { size 8{ 226{}} }Ra} {}$	226.025 402	$α α size 12{α} {}$	$1 . 60 \times 10^{3} y 1 . 60 \times 10^{3} y size 12{1 "." "60" times "10" rSup { size 8{3} } y} {}$
89	Actinium	227	$227 Ac 227 Ac size 12{rSup { size 8{ 227{}} }Ac} {}$	227.027 750	$α, β^{-} α, size 12{α,β rSup { size 8{ - {}} } } {}$	21.8 y
90	Thorium	228	$228 Th 228 Th size 12{rSup { size 8{ 228{}} }Th} {}$	228.028 715	$α α size 12{α} {}$	1.91 y
		232	$232 Th 232 Th size 12{rSup { size 8{ 232{}} }Th} {}$	232.038 054	100%, $α α size 12{α} {}$	$1 . 41 \times 10^{10} y 1 . 41 \times 10^{10} y size 12{1 "." "41" times "10" rSup { size 8{"10"} } y} {}$
91	Protactinium	231	$231 Pa 231 Pa size 12{rSup { size 8{ 231{}} }Pa} {}$	231.035 880	$α α size 12{α} {}$	$3 . 28 \times 10^{4} y 3 . 28 \times 10^{4} y size 12{3 "." "28" times "10" rSup { size 8{4} } y} {}$
92	Uranium	233	$233 U 233 U size 12{rSup { size 8{ 233{}} }U} {}$	233.039 628	$α α size 12{α} {}$	$1 . 59 \times 10^{3} y 1 . 59 \times 10^{3} y size 12{1 "." "59" times "10" rSup { size 8{3} } y} {}$
		235	$235 U 235 U size 12{rSup { size 8{ 235{}} }U} {}$	235.043 924	0.720%, $α α size 12{α} {}$	$7 . 04 \times 10^{8} y 7 . 04 \times 10^{8} y size 12{7 "." "04" times "10" rSup { size 8{8} } y} {}$
		236	$236 U 236 U size 12{rSup { size 8{ 236{}} }U} {}$	236.045 562	$α α size 12{α} {}$	$2 . 34 \times 10^{7} y 2 . 34 \times 10^{7} y size 12{2 "." "34" times "10" rSup { size 8{7} } y} {}$
		238	$238 U 238 U size 12{rSup { size 8{ 238{}} }U} {}$	238.050 784	99.2745%, $α α size 12{α} {}$	$4 . 47 \times 10^{9} y 4 . 47 \times 10^{9} y size 12{4 "." "47" times "10" rSup { size 8{9} } y} {}$
		239	$239 U 239 U size 12{rSup { size 8{ 239{}} }U} {}$	239.054 289	$β^{-} β^{-} size 12{β rSup { size 8{ - {}} } } {}$	23.5 min
93	Neptunium	239	$239 Np 239 Np size 12{rSup { size 8{ 239{}} }Np} {}$	239.052 933	$β^{-} β^{-} size 12{β rSup { size 8{ - {}} } } {}$	2.355 d
94	Plutonium	239	$239 Pu 239 Pu size 12{rSup { size 8{ 239{}} }Pu} {}$	239.052 157	$α α size 12{α} {}$	$2 . 41 \times 10^{4} y 2 . 41 \times 10^{4} y size 12{2 "." "41" times "10" rSup { size 8{4} } y} {}$
95	Americium	243	$243 Am 243 Am size 12{rSup { size 8{ 243{}} }Am} {}$	243.061 375	$α, α, size 12{α,} {}$ fission	$7 . 37 \times 10^{3} y 7 . 37 \times 10^{3} y size 12{7 "." "37" times "10" rSup { size 8{3} } y} {}$
96	Curium	245	$245 Cm 245 Cm size 12{rSup { size 8{ 245{}} }Cm} {}$	245.065 483	$α α size 12{α} {}$	$8 . 50 \times 10^{3} y 8 . 50 \times 10^{3} y size 12{8 "." "50" times "10" rSup { size 8{3} } y} {}$
97	Berkelium	247	$247 Bk 247 Bk size 12{rSup { size 8{ 247{}} }Bk} {}$	247.070 300	$α α size 12{α} {}$	$1 . 38 \times 10^{3} y 1 . 38 \times 10^{3} y size 12{1 "." "38" times "10" rSup { size 8{3} } y} {}$
98	Californium	249	$249 Cf 249 Cf size 12{rSup { size 8{ 249{}} }Cf} {}$	249.074 844	$α α size 12{α} {}$	351 y
99	Einsteinium	254	$254 Es 254 Es size 12{rSup { size 8{ 254{}} }Es} {}$	254.088 019	$α, β^{-} α, size 12{α,β rSup { size 8{ - {}} } } {}$	276 d
100	Fermium	253	$253 Fm 253 Fm size 12{rSup { size 8{ 253{}} }Fm} {}$	253.085 173	EC, $α α size 12{α} {}$	3.00 d
101	Mendelevium	255	$255 Md 255 Md size 12{rSup { size 8{ 255{}} }Md} {}$	255.091 081	EC, $α α size 12{α} {}$	27 min
102	Nobelium	255	$255 No 255 No size 12{rSup { size 8{ 255{}} }No} {}$	255.093 260	EC, $α α size 12{α} {}$	3.1 min
103	Lawrencium	257	$257 Lr 257 Lr size 12{rSup { size 8{ 257{}} }Lr} {}$	257.099 480	EC, $α α size 12{α} {}$	0.646 s
104	Rutherfordium	261	$261 Rf 261 Rf size 12{rSup { size 8{ 261{}} }Rf} {}$	261.108 690	$α α size 12{α} {}$	1.08 min
105	Dubnium	262	$262 Db 262 Db size 12{rSup { size 8{ 262{}} }Db} {}$	262.113 760	$α, α, size 12{α,} {}$ fission	34 s
106	Seaborgium	263	$263 Sg 263 Sg size 12{rSup { size 8{ 263{}} }Sg} {}$	263.11 86	$α, α, size 12{α,} {}$ fission	0.8 s
107	Bohrium	262	$262 Bh 262 Bh size 12{rSup { size 8{ 262{}} }Bh} {}$	262.123 1	$α α size 12{α} {}$	0.102 s
108	Hassium	264	$264 Hs 264 Hs size 12{rSup { size 8{ 264{}} }Hs} {}$	264.128 5	$α α size 12{α} {}$	0.08 ms
109	Meitnerium	266	$266 Mt 266 Mt size 12{rSup { size 8{ 266{}} }Mt} {}$	266.137 8	$α α size 12{α} {}$	3.4 ms

Table A1 Atomic Masses