|
|
atomic weight
|
|
|
The atomic weight of an element is the
weighted average of the isotope masses.
For example, 98.89% of all carbon atoms
are in the form of carbon-12 and almost
all of the remainder are carbon-13. The
atomic weight of carbon is then calculated
to be 0.9889 x 12.00000 + 0.0111 x
13.003354 = 12.01.
|
name
|
symbol
|
atomic number
|
atomic weight
|
|
actinium
|
Ac
|
89
|
[227]
|
|
aluminium
|
Al
|
13
|
26.981538 (2)
|
|
americium
|
Am
|
95
|
[243]
|
|
antimony
|
Sb
|
51
|
121.76 (1)
|
|
argon
|
Ar
|
18
|
39.948 (1)
|
|
arsenic
|
As
|
33
|
74.9216 (2)
|
|
astatine
|
At
|
85
|
[210]
|
|
barium
|
Ba
|
56
|
137.327 (7)
|
|
berkelium
|
Bk
|
97
|
[247]
|
|
beryllium
|
Be
|
4
|
9.012182 (3)
|
|
bismuth
|
Bi
|
83
|
208.98038 (2)
|
|
bohrium
|
Bh
|
107
|
[264]
|
|
boron
|
B
|
5
|
10.811 (7)
|
|
bromine
|
Br
|
35
|
79.904 (1)
|
|
cadmium
|
Cd
|
48
|
112.411 (8)
|
|
caesium
|
Cs
|
55
|
132.90545 (2)
|
|
calcium
|
Ca
|
20
|
40.078 (4)
|
|
californium
|
Cf
|
98
|
[251]
|
|
carbon
|
C
|
6
|
12.0107 (8)
|
|
cerium
|
Ce
|
58
|
140.116 (1)
|
|
chlorine
|
Cl
|
17
|
35.4527 (9)
|
|
chromium
|
Cr
|
24
|
51.9961 (6)
|
|
cobalt
|
Co
|
27
|
58.9332 (9)
|
|
copper
|
Cu
|
29
|
63.546 (3)
|
|
curium
|
Cm
|
96
|
[247]
|
|
dubnium
|
Db
|
105
|
[262]
|
|
dysprosium
|
Dy
|
66
|
162.5 (3)
|
|
einsteinium
|
Es
|
99
|
[252]
|
|
erbium
|
Er
|
68
|
167.26 (3)
|
|
europium
|
Eu
|
63
|
151.964 (1)
|
|
fermium
|
Fm
|
100
|
[257]
|
|
fluorine
|
F
|
9
|
18.9984032
(5)
|
|
francium
|
Fr
|
87
|
[223]
|
|
gadolinium
|
Gd
|
64
|
157.25 (3)
|
|
gallium
|
Ga
|
31
|
69.723 (1)
|
|
germanium
|
Ge
|
32
|
72.61 (2)
|
|
gold
|
Au
|
79
|
196.96655 (2)
|
|
hafnium
|
Hf
|
72
|
178.49 (2)
|
|
hassium
|
Hs
|
108
|
[269]
|
|
helium
|
He
|
2
|
4.002602 (2)
|
|
holmium
|
Ho
|
67
|
164.93032 (2)
|
|
hydrogen
|
H
|
1
|
1.00794 (7)
|
|
indium
|
In
|
49
|
114.818 (3)
|
|
iodine
|
I
|
53
|
126.90447 (3)
|
|
iridium
|
Ir
|
77
|
192.217 (3)
|
|
iron
|
Fe
|
26
|
55.845 (2)
|
|
krypton
|
Kr
|
36
|
83.8 (1)
|
|
lanthanum
|
La
|
57
|
138.9055 (2)
|
|
lawrencium
|
Lr
|
103
|
[262]
|
|
lead
|
Pb
|
82
|
207.2 (1)
|
|
lithium
|
Li
|
3
|
[6.941 (2)]
|
|
lutetium
|
Lu
|
71
|
174.967 (1)
|
|
magnesium
|
Mg
|
12
|
24.305 (6)
|
|
manganese
|
Mn
|
25
|
54.938049 (9)
|
|
meitnerium
|
Mt
|
109
|
[268]
|
|
mendelevium
|
Md
|
101
|
[258]
|
|
mercury
|
Hg
|
80
|
200.59 (2)
|
|
molybdenum
|
Mo
|
42
|
95.94 (1)
|
|
neodymium
|
Nd
|
60
|
144.24 (3)
|
|
neon
|
Ne
|
10
|
20.1797 (6)
|
|
neptunium
|
Np
|
93
|
[237]
|
|
nickel
|
Ni
|
28
|
58.6934 (2)
|
|
niobium
|
Nb
|
41
|
92.90638 (2)
|
|
nitrogen
|
N
|
7
|
14.00674 (7)
|
|
nobelium
|
No
|
102
|
[259]
|
|
osmium
|
Os
|
76
|
190.23 (3)
|
|
oxygen
|
O
|
8
|
15.9994 (3)
|
|
palladium
|
Pd
|
46
|
106.42 (1)
|
|
phosphorus
|
P
|
15
|
30.973762 (4)
|
|
platinum
|
Pt
|
78
|
195.078 (2)
|
|
plutonium
|
Pu
|
94
|
[244]
|
|
polonium
|
Po
|
84
|
[210]
|
|
potassium
|
K
|
19
|
39.0983 (1)
|
|
praseodymium
|
Pr
|
59
|
140.90765 (2)
|
|
promethium
|
Pm
|
61
|
[145]
|
|
protactinium
|
Pa
|
91
|
231.03588 (2)
|
|
radium
|
Ra
|
88
|
[226]
|
|
radon
|
Rn
|
86
|
[222]
|
|
rhenium
|
Re
|
75
|
186.207 (1)
|
|
rhodium
|
Rh
|
45
|
102.9055 (2)
|
|
rubidium
|
Rb
|
37
|
85.4678 (3)
|
|
ruthenium
|
Ru
|
44
|
101.07 (2)
|
|
rutherfordium
|
Rf
|
104
|
[261]
|
|
samarium
|
Sm
|
62
|
150.36 (3)
|
|
scandium
|
Sc
|
21
|
44.95591 (8)
|
|
seaborgium
|
Sg
|
106
|
[266]
|
|
selenium
|
Se
|
34
|
78.96 (3)
|
|
silicon
|
Si
|
14
|
28.0855 (3)
|
|
silver
|
Ag
|
47
|
107.8682 (2)
|
|
sodium
|
Na
|
11
|
22.98977 (2)
|
|
strontium
|
Sr
|
38
|
87.62 (1)
|
|
sulphur
|
S
|
16
|
32.066 (6)
|
|
tantalum
|
Ta
|
73
|
180.9479 (1)
|
|
technetium
|
Tc
|
43
|
[98]
|
|
tellurium
|
Te
|
52
|
127.6 (3)
|
|
terbium
|
Tb
|
65
|
158.92534 (2)
|
|
thallium
|
Tl
|
81
|
204.3833 (2)
|
|
thorium
|
Th
|
90
|
232.0381 (1)
|
|
thulium
|
Tm
|
69
|
168.93421 (2)
|
|
tin
|
Sn
|
50
|
118.71 (7)
|
|
titanium
|
Ti
|
22
|
47.867 (1)
|
|
tungsten
|
W
|
74
|
183.84 (1)
|
|
ununbium
|
Uub
|
112
|
[277]
|
|
ununnilium
|
Uun
|
110
|
[269]
|
|
unununium
|
Uuu
|
111
|
[272]
|
|
uranium
|
U
|
92
|
238.0289 (1)
|
|
vanadium
|
V
|
23
|
50.9415 (1)
|
|
xenon
|
Xe
|
54
|
131.29 (2)
|
|
ytterbium
|
Yb
|
70
|
173.04 (3)
|
|
yttrium
|
Y
|
39
|
88.90585 (2)
|
|
zinc
|
Zn
|
30
|
65.39 (2)
|
|
zirconium
|
Zr
|
40
|
91.224 (2)
|
|
|
|
|