Table of Atomic Masses (2005)
Name
actinium
aluminum
americium
antimony
argon
arsenic
astatine
barium
berkelium
beryllium
bismuth
bohrium
boron
bromine
cadmium
calcium
californium
carbon
cerium
cesium
chlorine
chromium
cobalt
copper
curium
darmstadtium
dubnium
dysprosium
einsteinium
erbium
europium
fermium
fluorine
francium
gadolinium
gallium
germanium
gold
hafnium
hassium
Symbol
Ac
Al
Am
Sb
Ar
As
At
Ba
Bk
Be
Bi
Bh
B
Br
Cd
Ca
Cf
C
Ce
Cs
Cl
Cr
Co
Cu
Cm
Ds
Db
Dy
Es
Er
Eu
Fm
F
Fr
Gd
Ga
Ge
Au
Hf
Hs
Atomic
number
89
13
95
51
18
33
85
56
97
4
83
107
5
35
48
20
98
6
58
55
17
24
27
29
96
110
105
66
99
68
63
100
9
87
64
31
32
79
72
108
Atomic Weight
[227]
26.9815386 (8)
[243]
121.760 (1)
39.948 (1)
74.92160 (2)
[210]
137.327 (7)
[247]
9.012182 (3)
208.98040 (1)
[264]
10.811 (7)
79.904 (1)
112.411 (8)
40.078 (4)
[251]
12.0107 (8)
140.116 (1)
132.9054519 (2)
35.453 (2)
51.9961 (6)
58.933195 (5)
63.546 (3)
[247]
[281]
[262]
162.500 (3)
[252]
167.259 (3)
151.964 (1)
[257]
18.9984032 (5)
[223]
157.25 (3)
69.723 (1)
72.64 (2)
196.966569 (4)
178.49 (2)
[277]
helium
holmium
hydrogen
indium
iodine
iridium
iron
krypton
lanthanum
lawrencium
lead
lithium
lutetium
magnesium
manganese
meitnerium
mendelevium
mercury
molybdenum
neodymium
neon
neptunium
nickel
niobium
nitrogen
nobelium
osmium
oxygen
palladium
phosphorus
platinum
plutonium
polonium
potassium
praseodymium
promethium
protactinium
radium
radon
rhenium
rhodium
rubidium
ruthenium
rutherfordium
samarium
He
Ho
H
In
I
Ir
Fe
Kr
La
Lr
Pb
Li
Lu
Mg
Mn
Mt
Md
Hg
Mo
Nd
Ne
Np
Ni
Nb
N
No
Os
O
Pd
P
Pt
Pu
Po
K
Pr
Pm
Pa
Ra
Rn
Re
Rh
Rb
Ru
Rf
Sm
2
67
1
49
53
77
26
36
57
103
82
3
71
12
25
109
101
80
42
60
10
93
28
41
7
102
76
8
46
15
78
94
84
19
59
61
91
88
86
75
45
37
44
104
62
4.002602 (2)
164.93032 (2)
1.00794 (7)
114.818 (3)
126.90447 (3)
192.217 (3)
55.845 (2)
83.798 (2)
138.90547 (7)
[262]
207.2 (1)
6.941 (2)
174.967 (1)
24.3050 (6)
54.938045 (5)
[268]
[258]
200.59 (2)
95.94 (2)
144.242 (3)
20.1797 (6)
[237]
58.6934 (2)
92.90638 (2)
14.0067 (2)
[259]
190.23 (3)
15.9994 (3)
106.42 (1)
30.973762 (2)
195.084 (9)
[244]
[209]
39.0983 (1)
140.90765 (2)
[145]
231.03588 (2)
[226]
[222]
186.207 (1)
102.90550 (2)
85.4678 (3)
101.07 (2)
[261]
150.36 (2)
scandium
seaborgium
selenium
silicon
silver
sodium
strontium
sulfur
tantalum
technetium
tellurium
terbium
thallium
thorium
thulium
tin
titanium
tungsten
ununbium
ununhexium
ununquadrium
unununium
uranium
vanadium
xenon
ytterbium
yttrium
zinc
zirconium
Sc
Sg
Se
Si
Ag
Na
Sr
S
Ta
Tc
Te
Tb
Tl
Th
Tm
Sn
Ti
W
Uub
Uuh
Uuq
Uuu
U
V
Xe
Yb
Y
Zn
Zr
21
106
34
14
47
11
38
16
73
43
52
65
81
90
69
50
22
74
112
116
114
111
92
23
54
70
39
30
40
44.955912 (6)
[266]
78.96 (3)
28.0855 (3)
107.8682 (2)
22.98976928 (2)
87.62 (1)
32.065 (5)
180.94788 (2)
[98]
127.60 (3)
158.92535 (2)
204.3833 (2)
232.03806 (2)
168.93421 (2)
118.710 (7)
47.867 (1)
183.84 (1)
[285]
[292]
[289]
[272]
238.02891 (3)
50.9415 (1)
131.293 (6)
173.04 (3)
88.90585 (2)
65.409(4)
91.224 (2)
The number in parentheses following the atomic weight value gives the uncertainty in the last
digit. An entry in [square brackets] indicates the mass number of the longest-lived isotope of an
element that has no stable isotopes and for which a standard atomic weight cannot be defined
because of wide variability in isotopic composition (or complete absence) in nature.
reflects 2005 IUPAC recommendations taken from
http://www.iupac.org/news/archives/2005/atomic-weights_revised05.html
accessed July 4, 2006
taken from http://physics.nist.gov/PhysRefData/Compositions/
accessed April 22, 2006