Chapter 15: Atomic Masses

Last updated

Mar 12, 2024
Save as PDF
- 6: Appendix
- Chapter 16: Selected Radioactive Isotopes

$\newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} }$

$\newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}}$

$\newcommand{\id}{\mathrm{id}}$ $\newcommand{\Span}{\mathrm{span}}$

( \newcommand{\kernel}{\mathrm{null}\,}\) $\newcommand{\range}{\mathrm{range}\,}$

$\newcommand{\RealPart}{\mathrm{Re}}$ $\newcommand{\ImaginaryPart}{\mathrm{Im}}$

$\newcommand{\Argument}{\mathrm{Arg}}$ $\newcommand{\norm}[1]{\| #1 \|}$

$\newcommand{\inner}[2]{\langle #1, #2 \rangle}$

$\newcommand{\Span}{\mathrm{span}}$

$\newcommand{\id}{\mathrm{id}}$

$\newcommand{\Span}{\mathrm{span}}$

$\newcommand{\kernel}{\mathrm{null}\,}$

$\newcommand{\range}{\mathrm{range}\,}$

$\newcommand{\RealPart}{\mathrm{Re}}$

$\newcommand{\ImaginaryPart}{\mathrm{Im}}$

$\newcommand{\Argument}{\mathrm{Arg}}$

$\newcommand{\norm}[1]{\| #1 \|}$

$\newcommand{\inner}[2]{\langle #1, #2 \rangle}$

$\newcommand{\Span}{\mathrm{span}}$ $\newcommand{\AA}{\unicode[.8,0]{x212B}}$

$\newcommand{\vectorA}[1]{\vec{#1}} % arrow$

$\newcommand{\vectorAt}[1]{\vec{\text{#1}}} % arrow$

$\newcommand{\vectorB}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} }$

$\newcommand{\vectorC}[1]{\textbf{#1}}$

$\newcommand{\vectorD}[1]{\overrightarrow{#1}}$

$\newcommand{\vectorDt}[1]{\overrightarrow{\text{#1}}}$

$\newcommand{\vectE}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{\mathbf {#1}}}}$

$\newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} }$

$\newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}}$

$\newcommand{\avec}{\mathbf a}$

$\newcommand{\bvec}{\mathbf b}$

$\newcommand{\cvec}{\mathbf c}$

$\newcommand{\dvec}{\mathbf d}$

$\newcommand{\dtil}{\widetilde{\mathbf d}}$

$\newcommand{\evec}{\mathbf e}$

$\newcommand{\fvec}{\mathbf f}$

$\newcommand{\nvec}{\mathbf n}$

$\newcommand{\pvec}{\mathbf p}$

$\newcommand{\qvec}{\mathbf q}$

$\newcommand{\svec}{\mathbf s}$

$\newcommand{\tvec}{\mathbf t}$

$\newcommand{\uvec}{\mathbf u}$

$\newcommand{\vvec}{\mathbf v}$

$\newcommand{\wvec}{\mathbf w}$

$\newcommand{\xvec}{\mathbf x}$

$\newcommand{\yvec}{\mathbf y}$

$\newcommand{\zvec}{\mathbf z}$

$\newcommand{\rvec}{\mathbf r}$

$\newcommand{\mvec}{\mathbf m}$

$\newcommand{\zerovec}{\mathbf 0}$

$\newcommand{\onevec}{\mathbf 1}$

$\newcommand{\real}{\mathbb R}$

$\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}$

$\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}$

$\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}$

$\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}$

$\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}$

$\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}$

$\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}$

$\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}$

$\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}$

$\newcommand{\laspan}[1]{\text{Span}\{#1\}}$

$\newcommand{\bcal}{\cal B}$

$\newcommand{\ccal}{\cal C}$

$\newcommand{\scal}{\cal S}$

$\newcommand{\wcal}{\cal W}$

$\newcommand{\ecal}{\cal E}$

$\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}$

$\newcommand{\gray}[1]{\color{gray}{#1}}$

$\newcommand{\lgray}[1]{\color{lightgray}{#1}}$

$\newcommand{\rank}{\operatorname{rank}}$

$\newcommand{\row}{\text{Row}}$

$\newcommand{\col}{\text{Col}}$

$\renewcommand{\row}{\text{Row}}$

$\newcommand{\nul}{\text{Nul}}$

$\newcommand{\var}{\text{Var}}$

$\newcommand{\corr}{\text{corr}}$

$\newcommand{\len}[1]{\left|#1\right|}$

$\newcommand{\bbar}{\overline{\bvec}}$

$\newcommand{\bhat}{\widehat{\bvec}}$

$\newcommand{\bperp}{\bvec^\perp}$

$\newcommand{\xhat}{\widehat{\xvec}}$

$\newcommand{\vhat}{\widehat{\vvec}}$

$\newcommand{\uhat}{\widehat{\uvec}}$

$\newcommand{\what}{\widehat{\wvec}}$

$\newcommand{\Sighat}{\widehat{\Sigma}}$

$\newcommand{\lt}{<}$

$\newcommand{\gt}{>}$

$\newcommand{\amp}{&}$

$\definecolor{fillinmathshade}{gray}{0.9}$

Table $\PageIndex{1}$ : 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	$n$	1.008 665	$\beta^{-}$	10.37 min
1	Hydrogen	1	${ }^{1} \mathrm{H}$	1.007 825	99.985%
	Deuterium	2	${ }^{2} \mathrm{H} \text { or } \mathrm{D}$	2.014 102	0.015%
	Tritium	3	${ }^{3} \mathrm{H} \text { or } \mathrm{T}$	3.016 050	$\beta^{-}$	12.33 y
2	Helium	3	${ }^{3} \mathrm{He}$	3.016 030	$1.38 \times 10^{-4} \%$
		4	${ }^{4} \mathrm{He}$	4.002 603	$\approx 100 \%$
3	Lithium	6	${ }^{6} \mathrm{Li}$	6.015 121	7.5%
		7	${ }^{7} \mathrm{Li}$	7.016 003	92.5%
4	Beryllium	7	${ }^{7} \mathrm{Be}$	7.016 928	EC	53.29 d
		9	${ }^{9} \mathrm{Be}$	9.012 182	100%
5	Boron	10	${ }^{10} \mathrm{~B}$	10.012 937	19.9%
		11	${ }^{11} \mathrm{~B}$	11.009 305	80.1%
6	Carbon	11	${ }^{11} \mathrm{C}$	11.011 432	EC, $\beta^{+}$
		12	${ }^{12} \mathrm{C}$	12.000 000	98.90%
		13	${ }^{13} \mathrm{C}$	13.003 355	1.10%
		14	${ }^{14} \mathrm{C}$	14.003 241	$\beta^{-}$	5730 y
7	Nitrogen	13	${ }^{13} \mathrm{~N}$	13.005 738	$\beta^{+}$	9.96 min
		14	${ }^{14} \mathrm{~N}$	14.003 074	99.63%
		15	${ }^{15} \mathrm{~N}$	15.000 108	0.37%
8	Oxygen	15	${ }^{15} \mathrm{O}$	15.003 065	EC, $\beta^{+}$	122 s
		16	${ }^{16} \mathrm{O}$	15.994 915	99.76%
		18	${ }^{18} \mathrm{O}$	17.999 160	0.200%
9	Fluorine	18	${ }^{18} \mathrm{~F}$	18.000 937	EC, $\beta^{+}$	1.83 h
		19	${ }^{19} \mathrm{~F}$	18.998 403	100%
10	Neon	20	${ }^{20} \mathrm{Ne}$	19.992 435	90.51%
		22	${ }^{22} \mathrm{Ne}$	21.991 383	9.22%
11	Sodium	22	${ }^{22} \mathrm{Na}$	21.994 434	$\beta^{+}$	2.602 y
		23	${ }^{23} \mathrm{Na}$	22.989 767	100%
		24	${ }^{24} \mathrm{Na}$	23.990 961	$\beta^{-}$	14.96 h
12	Magnesium	24	${ }^{24} \mathrm{Mg}$	23.985 042	78.99%
13	Aluminum	27	${ }^{27} \mathrm{Al}$	26.981 539	100%
14	Silicon	28	${ }^{28} \mathrm{Si}$	27.976 927	92.23%	2.62h
		31	${ }^{31} \mathrm{Si}$	30.975 362	$\beta^{-}$
15	Phosphorus	31	${ }^{31} \mathrm{P}$	30.973 762	100%
		32	${ }^{32} \mathrm{P}$	31.973 907	$\beta^{-}$	14.28 d
16	Sulfur	32	$32 \mathrm{S}$	31.972 070	95.02%
		35	${ }^{35} \mathrm{S}$	34.969 031	$\beta^{-}$	87.4 d
17	Chlorine	35	${ }^{35} \mathrm{Cl}$	34.968 852	75.77%
		37	${ }^{37} \mathrm{Cl}$	36.965 903	24.23%
18	Argon	40	${ }^{40} \mathrm{Ar}$	39.962 384	99.60%
19	Potassium	39	${ }^{39} \mathrm{~K}$	38.963 707	93.26%
		40	${ }^{40} \mathrm{~K}$	39.963 999	0.0117%, EC, $\beta^{-}$	$1.28 \times 10^{9} \mathrm{y}$
20	Calcium	40	${ }^{40} \mathrm{Ca}$	39.962 591	96.94%
21	Scandium	45	${ }^{45} \mathrm{Sc}$	44.955 910	100%
22	Titanium	48	${ }^{48} \mathrm{Ti}$	47.947 947	73.8%
23	Vanadium	51	${ }^{51} \mathrm{~V}$	50.943 962	99.75%
24	Chromium	52	${ }^{52} \mathrm{Cr}$	51.940 509	83.79%
25	Manganese	55	${ }^{55} \mathrm{Mn}$	54.938 047	100%
26	Iron	56	${ }^{56} \mathrm{Fe}$	55.934 939	91.72%
27	Cobalt	59	${ }^{59} \mathrm{Co}$	58.933 198	100%
		60	${ }^{60} \mathrm{Co}$	59.933 819	$\beta^{-}$	5.271 y
28	Nickel	58	${ }^{58} \mathrm{Ni}$	57.935 346	68.27%
		60	$60 \mathrm{Ni}$	59.930 788	26.10%
29	Copper	63	${ }^{63} \mathrm{Cu}$	62.939 598	69.17%
		65	${ }^{65} \mathrm{Cu}$	64.927 793	30.83%
30	Zinc	64	${ }^{64} \mathrm{Zn}$	63.929 145	48.6%
		66	${ }^{66} \mathrm{Zn}$	65.926 034	27.9%
31	Gallium	69	${ }^{69} \mathrm{Ga}$	68.925 580	60.1%
32	Germanium	72	${ }^{72} \mathrm{Ge}$	71.922 079	27.4%
		74	${ }^{74} \mathrm{Ge}$	73.921 177	36.5%
33	Arsenic	75	${ }^{75} \mathrm{As}$	74.921 594	100%
34	Selenium	80	${ }^{80} \mathrm{Se}$	79.916 520	49.7%
35	Bromine	79	${ }^{79} \mathrm{Br}$	78.918 336	50.69%
36	Krypton	84	${ }^{84} \mathrm{Kr}$	83.911 507	57.0%
37	Rubidium	85	${ }^{85} \mathrm{Rb}$	84.911 794	72.17%
38	Strontium	86	${ }^{86} \mathrm{Sr}$	85.909 267	9.86%
		88	${ }^{88} \mathrm{Sr}$	87.905 619	82.58%
		90	${ }^{90} \mathrm{Sr}$	89.907 738	$\beta^{-}$	28.8 y
39	Yttrium	89	${ }^{89} \mathrm{Y}$	88.905 849	100%
		90	${ }^{90} \mathrm{Y}$	89.907 152	$\beta^{-}$	64.1 h
40	Zirconium	90	${ }^{90} \mathrm{Zr}$	89.904 703	51.45%
41	Niobium	93	${ }^{93} \mathrm{Nb}$	92.906 377	100%
42	Molybdenum	98	${ }^{98} \mathrm{Mo}$	97.905 406	24.13%
43	Technetium	98	${ }^{98} \mathrm{Tc}$	97.907 215	$\beta^{-}$	$4.2 \times 10^{6} \mathrm{y}$
44	Ruthenium	102	${ }^{102} \mathrm{Ru}$	101.904 348	31.6%
45	Rhodium	103	${ }^{103} \mathrm{Rh}$	102.905 500	100%
46	Palladium	106	${ }^{106} \mathrm{Pd}$	105.903 478	27.33%
47	Silver	107	${ }^{107} \mathrm{Ag}$	106.905 092	51.84%
		109	${ }^{109} \mathrm{Ag}$	108.904 757	48.16%
48	Cadmium	114	${ }^{114} \mathrm{Cd}$	113.903 357	28.73%
49	Indium	115	${ }^{115} \mathrm{In}$	114.903 880	95.7%, $\beta^{-}$	$4.4 \times 10^{14} \mathrm{y}$
50	Tin	120	${ }^{120} \mathrm{Sn}$	119.902 200	32.59%
51	Antimony	121	${ }^{121} \mathrm{Sb}$	120.903 821	57.3%
52	Tellurium	130	${ }^{130} \mathrm{Te}$	129.906 229	33.8%, $\beta^{-}$	$2.5 \times 10^{21} \mathrm{y}$
53	Iodine	127	${ }^{127} \mathrm{I}$	126.904 473	100%
		131	${ }^{131} \mathrm{I}$	130.906 114	$\beta^{-}$	8.040 d
54	Xenon	132	${ }^{132} \mathrm{Xe}$	131.904 144	26.9%
		136	${ }^{136} \mathrm{Xe}$	135.907 214	8.9%
55	Cesium	133	${ }^{133} \mathrm{Cs}$	132.905 429	100%
		134	${ }^{134} \mathrm{Cs}$	133.906 696	EC, $\beta^{-}$	2.06 y
56	Barium	137	${ }^{137} \mathrm{Ba}$	136.905 812	11.23%
		138	${ }^{138} \mathrm{Ba}$	137.905 232	71.70%
57	Lanthanum	139	${ }^{139} \mathrm{La}$	138.906 346	99.91%
58	Cerium	140	${ }^{140} \mathrm{Ce}$	139.905 433	88.48%
59	Praseodymium	141	${ }^{141} \mathrm{Pr}$	140.907 647	100%
60	Neodymium	142	${ }^{142} \mathrm{Nd}$	141.907 719	27.13%
61	Promethium	145	${ }^{145} \mathrm{Pm}$	144.912 743	EC, $\alpha$	17.7 y
62	Samarium	152	${ }^{152} \mathrm{Sm}$	151.919 729	26.7%
63	Europium	153	${ }^{153} \mathrm{Eu}$	152.921 225	52.2%
64	Gadolinium	158	${ }^{158} \mathrm{Gd}$	157.924 099	24.84%
65	Terbium	159	${ }^{159} \mathrm{Tb}$	158.925 342	100%
66	Dysprosium	164	${ }^{164} \mathrm{Dy}$	163.929 171	28.2%
67	Holmium	165	${ }^{165} \mathrm{Ho}$	164.930 319	100%
68	Erbium	166	${ }^{166} \mathrm{Er}$	165.930 290	33.6%
69	Thulium	169	${ }^{169} \mathrm{Tm}$	168.934 212	100%
70	Ytterbium	174	${ }^{174} \mathrm{Yb}$	173.938 859	31.8%
71	Lutecium	175	${ }^{175} \mathrm{Lu}$	174.940 770	97.41%
72	Hafnium	180	${ }^{180} \mathrm{Hf}$	179.946 545	35.10%
73	Tantalum	181	${ }^{181} \mathrm{Ta}$	180.947 992	99.98%
74	Tungsten	184	${ }^{184} \mathrm{W}$	183.950 928	30.67%
75	Rhenium	187	${ }^{187} \mathrm{Re}$	186.955 744	62.6%, $\beta^{-}$	$4.6 \times 10^{10} \mathrm{y}$
76	Osmium	191	${ }^{191} \mathrm{Os}$	190.960 920	$\beta^{-}$	15.4 d
		192	${ }^{192} \mathrm{Os}$	191.961 467	41.0%
77	Iridium	191	${ }^{191} \mathrm{Ir}$	190.960 584	37.3%
		193	${ }^{193} \mathrm{Ir}$	192.962 917	62.7%
78	Platinum	195	${ }^{195} \mathrm{Pt}$	194.964 766	33.8%
79	Gold	197	${ }^{197} \mathrm{Au}$	196.966 543	100%
		198	${ }^{198} \mathrm{Au}$	197.968 217	$\beta^{-}$	2.696 d
80	Mercury	199	${ }^{199} \mathrm{Hg}$	198.968 253	16.87%
		202	${ }^{202} \mathrm{Hg}$	201.970 617	29.86%
81	Thallium	205	${ }^{205} \mathrm{Tl}$	204.974 401	70.48%
82	Lead	206	${ }^{206} \mathrm{Pb}$	205.974 440	24.1%
		207	${ }^{207} \mathrm{Pb}$	206.975 872	22.1%
		208	${ }^{208} \mathrm{Pb}$	207.976 627	52.4%
		210	${ }^{210} \mathrm{Pb}$	209.984 163	$\alpha, \beta^{-}$	22.3 y
		211	${ }^{211} \mathrm{Pb}$	210.988 735	$\beta^{-}$	36.1 min
		212	${ }^{212} \mathrm{Pb}$	211.991 871	$\beta^{-}$	10.64 h
83	Bismuth	209	${ }^{209} \mathrm{Bi}$	208.980 374	100%
		211	${ }^{211} \mathrm{Bi}$	210.987 255	$\alpha, \beta^{-}$	2.14 min
84	Polonium	210	${ }^{210} \mathrm{Po}$	209.982 848	$\alpha$	138.38 d
85	Astatine	218	${ }^{218} \mathrm{At}$	218.008 684	$\alpha, \beta^{-}$	1.6 s
86	Radon	222	${ }^{222} \mathrm{Rn}$	222.017 570	$\alpha$	3.82 d
87	Francium	223	${ }^{223} \mathrm{Fr}$	223.019 733	$\alpha, \beta^{-}$	21.8 min
88	Radium	226	${ }^{226} \mathrm{Ra}$	226.025 402	$\alpha$	$1.60 \times 10^{3} \mathrm{y}$
89	Actinium	227	${ }^{227} \mathrm{Ac}$	227.027 750	$\alpha, \beta^{-}$	21.8 y
90	Thorium	228	${ }^{228} \mathrm{Th}$	228.028 715	$\alpha$	1.91 y
		232	${ }^{232} \mathrm{Th}$	232.038 054	100%, $\alpha$	$1.41 \times 10^{10} \mathrm{y}$
91	Protactinium	231	${ }^{231} \mathrm{~Pa}$	231.035 880	$\alpha$	$3.28 \times 10^{4} \mathrm{y}$
92	Uranium	233	${ }^{233} \mathrm{U}$	233.039 628	$\alpha$	$1.59 \times 10^{3} \mathrm{y}$
		235	${ }^{235} \mathrm{U}$	235.043 924	0.720%, $\alpha$	$7.04 \times 10^{8} \mathrm{y}$
		236	${ }^{236} \mathrm{U}$	236.045 562	$\alpha$	$2.34 \times 10^{7} \mathrm{y}$
		238	${ }^{238} \mathrm{U}$	238.050 784	99.2745%, $\alpha$	$4.47 \times 10^{9} \mathrm{y}$
		239	${ }^{239} \mathrm{U}$	239.054 289	$\beta^{-}$	23.5 min
93	Neptunium	239	${ }^{239} \mathrm{Np}$	239.052 933	$\beta^{-}$	2.355 d
94	Plutonium	239	${ }^{239} \mathrm{Pu}$	239.052 157	$\alpha$	$2.41 \times 10^{4} \mathrm{y}$
95	Americium	243	${ }^{243} \mathrm{Am}$	243.061 375	$\alpha$ , fission	$7.37 \times 10^{3} \mathrm{y}$
96	Curium	245	${ }^{245} \mathrm{Cm}$	245.065 483	$\alpha$	$8.50 \times 10^{3} \mathrm{y}$
97	Berkelium	247	${ }^{247} \mathrm{Bk}$	247.070 300	$\alpha$	$1.38 \times 10^{3} \mathrm{y}$
98	Californium	249	${ }^{249} \mathrm{Cf}$	249.074 844	$\alpha$	351 y
99	Einsteinium	254	${ }^{254} \mathrm{Es}$	254.088 019	$\alpha, \beta^{-}$	276 d
100	Fermium	253	${ }^{253} \mathrm{Fm}$	253.085 173	EC, $\alpha$	3.00 d
101	Mendelevium	255	${ }^{255} \mathrm{Md}$	255.091 081	EC, $\alpha$	27 min
102	Nobelium	255	${ }^{255} \mathrm{No}$	255.093 260	EC, $\alpha$	3.1 min
103	Lawrencium	257	${ }^{257} \mathrm{Lr}$	257.099 480	EC, $\alpha$	0.646 s
104	Rutherfordium	261	${ }^{261} \mathrm{Rf}$	261.108 690	$\alpha$	1.08 min
105	Dubnium	262	${ }^{262} \mathrm{Db}$	262.113 760	$\alpha$ , fission	34 s
106	Seaborgium	263	${ }^{263} \mathrm{Sg}$	263.11 86	$\alpha$ , fission	0.8 s
107	Bohrium	262	${ }^{262} \mathrm{Bh}$	262.123 1	$\alpha$	0.102 s
108	Hassium	264	${ }^{264} \mathrm{Hs}$	264.128 5	$\alpha$	0.08 ms
109	Meitnerium	266	${ }^{266} \mathrm{Mt}$	266.137 8	$\alpha$	3.4 ms

Search

Text Color

Text Size

Margin Size

Font Type

Support Center

How can we help?