1
H
hydrogen
1.008
2
He
helium
4.0026
3
Li
lithium
6.94
4
Be
beryllium
9.0122
5
B
boron
10.81
6
C
carbon
12.011
7
N
nitrogen
14.007
8
O
oxygen
15.999
9
F
fluorine
18.998
10
Ne
neon
20.180
11
Na
sodium
22.990
12
Mg
magnesium
24.305
13
Al
aluminium
26.982
14
Si
silicon
28.085
15
P
phosphorus
30.974
16
S
sulfur
32.06
17
Cl
chlorine
35.45
18
Ar
argon
39.95
19
K
potassium
39.098
20
Ca
calcium
40.078
21
Sc
scandium
44.956
22
Ti
titanium
47.867
23
V
vanadium
50.942
24
Cr
chromium
51.996
25
Mn
manganese
54.938
26
Fe
iron
55.845
27
Co
cobalt
58.933
28
Ni
nickel
58.693
29
Cu
copper
63.546
30
Zn
zinc
65.38
31
Ga
gallium
69.723
32
Ge
germanium
72.630
33
As
arsenic
74.922
34
Se
selenium
78.971
35
Br
bromine
79.904
36
Kr
krypton
83.798
37
Rb
rubidium
85.468
38
Sr
strontium
87.62
39
Y
yttrium
88.906
40
Zr
zirconium
91.224
41
Nb
niobium
92.906
42
Mo
molybdenum
95.95
43
Tc
technetium
[97]
44
Ru
ruthenium
101.07
45
Rh
rhodium
102.91
46
Pd
palladium
106.42
47
Ag
silver
107.87
48
Cd
cadmium
112.41
49
In
indium
114.82
50
Sn
tin
118.71
51
Sb
antimony
121.76
52
Te
tellurium
127.60
53
I
iodine
126.90
54
Xe
xenon
131.29
55
Cs
caesium
132.91
56
Ba
barium
137.33
71
Lu
lutetium
174.97
72
Hf
hafnium
178.49
73
Ta
tantalum
180.95
74
W
tungsten
183.84
75
Re
rhenium
186.21
76
Os
osmium
190.23
77
Ir
iridium
192.22
78
Pt
platinum
195.08
79
Au
gold
196.97
80
Hg
mercury
200.59
81
Tl
thallium
204.38
82
Pb
lead
207.2
83
Bi
bismuth
208.98
84
Po
polonium
[209]
85
At
astatine
[210]
86
Rn
radon
[222]
87
Fr
francium
[223]
88
Ra
radium
[226]
103
Lr
lawrencium
[266]
104
Rf
rutherfordium
[267]
105
Db
dubnium
[268]
106
Sg
seaborgium
[269]
107
Bh
bohrium
[270]
108
Hs
hassium
[269]
109
Mt
meitnerium
[278]
110
Ds
darmstadtium
[281]
111
Rg
roentgenium
[282]
112
Cn
copernicium
[285]
113
Nh
nihonium
[286]
114
Fl
flerovium
[289]
115
Mc
moscovium
[290]
116
Lv
livermorium
[293]
117
Ts
tennessine
[294]
118
Og
oganesson
[294]
57
La
lanthanum
138.91
58
Ce
cerium
140.12
59
Pr
praseodymium
140.91
60
Nd
neodymium
144.24
61
Pm
promethium
[145]
62
Sm
samarium
150.36
63
Eu
europium
151.96
64
Gd
gadolinium
157.25
65
Tb
terbium
158.93
66
Dy
dysprosium
162.50
67
Ho
holmium
164.93
68
Er
erbium
167.26
69
Tm
thulium
168.93
70
Yb
ytterbium
173.05
89
Ac
actinium
[227]
90
Th
thorium
232.04
91
Pa
protactinium
231.04
92
U
uranium
238.03
93
Np
neptunium
[237]
94
Pu
plutonium
[244]
95
Am
americium
[243]
96
Cm
curium
[247]
97
Bk
berkelium
[247]
98
Cf
californium
[251]
99
Es
einsteinium
[252]
100
Fm
fermium
[257]
101
Md
mendelevium
[258]
102
No
nobelium
[259]
1
H
hydrogen
1.008

General properties

Group
group 1 (H and alkali metals)
Period
period 1
Category
nonmetals
Standard atomic weight
1.008
[1.007 84, 1.008 11]
Melting point
(H₂) 13.99 K (-259.16 °C)
Boiling point
(H₂) 20.271 K (-252.879 °C)
Phase at STP
gas

Additional properties

Block
s-block
Electron configuration
1s¹
Electrons per shell
1
Electronegativity
2.20
Density
0.08988 g/L
Oxidation states
−1, +1 (an amphoteric oxide)
CAS Number
1333-74-0