The Modern Periodic Table of the Elements
1
18
Hydrogen
Average relative masses
are rounded to two
decimal places.
1
H
1.01
2.1
2
Lithium
Beryllium
3
4
Li
Be
6.94
1.0
9.01
1.5
All average masses are to
be treated as measured
quantities, and subject to
significant figure rules. Do
not round them further
when performing
calculations.
Element name
Helium
Mercury
2
Atomic #
80
He
Hg
Symbol
200.59
Avg. Mass
14
15
16
17
Boron
Carbon
Nitrogen
Oxygen
Fluorine
4.00
--Neon
5
6
7
8
9
10
B
C
N
O
F
Ne
10.81
2.0
1.9
Electronegativity
13
12.01
2.5
14.01
3.0
16.00
3.5
19.00
4.0
20.18
---
Sodium
Magnesium
Aluminum
Silicon
Phosphorus
Sulfur
Chlorine
11
12
13
14
15
16
17
18
Na
Mg
Al
Si
P
S
Cl
Ar
22.99
0.9
24.31
1.2
3
4
5
6
7
8
9
10
11
12
26.98
1.5
28.09
1.8
30.97
2.1
32.07
2.5
Argon
35.45
3.0
39.95
--Krypton
Potassium
Calcium
Scandium
Titanium
Vanadium
Chromium
Manganese
Iron
Cobalt
Nickel
Copper
Zinc
Gallium
Germanium
Arsenic
Selenium
Bromine
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
Ca
Sc
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
Ga
Ge
As
Se
Br
Kr
40.08
1.0
44.96
1.3
63.55
1.9
65.39
1.6
69.72
1.6
72.61
1.8
74.92
2.0
78.96
2.4
K
39.10
0.8
47.88
1.5
50.94
1.6
52.00
1.6
54.94
1.5
55.85
1.8
Molybdenum
58.93
1.8
58.69
1.8
79.90
2.8
83.80
3.0
Rubidium
Strontium
Yttrium
Zirconium
Niobium
Technetium
Ruthenium
Rhodium
Palladium
Silver
Cadmium
Indium
Tin
Antimony
Tellurium
Iodine
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
Rb
Sr
Y
Zr
Nb
Mo
Tc
Ru
Rh
Pd
Ag
Cd
In
Sn
Sb
Te
I
Xe
92.91
1.6
95.94
1.8
(98)
1.9
101.07
2.2
102.91
2.2
107.87
1.9
112.41
1.7
114.82
1.7
118.71
1.8
121.76
1.9
127.60
2.1
126.90
2.5
131.29
2.6
85.47
0.8
87.62
1.0
Cesium
Barium
55
56
Cs
Ba
132.91
0.7
137.33
0.9
Francium
Radium
87
88
Fr
Ra
(223)
0.7
57-70
*
88.91
1.2
91.22
1.4
Lutetium
Hafnium
Tantalum
Tungsten
Rhenium
Osmium
Iridium
Platinum
Gold
Mercury
Thallium
Lead
Bismuth
Polonium
Astatine
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
Lu
Hf
Ta
W
Re
Os
Ir
Pt
Au
Hg
Tl
Pb
Bi
Po
At
Rn
174.97
1.1
178.49
1.3
180.95
1.5
183.84
1.7
186.21
1.9
190.23
2.2
192.22
2.2
195.08
2.2
196.97
2.4
200.59
1.9
204.38
1.8
207.20
1.8
Lawrencium
89-102
**
(226)
0.9
*lanthanides
**actinides
106.42
2.2
Xenon
Radon
208.98
1.9
(209)
2.0
(210)
2.2
(222)
2.4
Ununoctium
Rutherfordium
Dubnium
Seaborgium
Bohrium
Hassium
Meitnerium
Darmstadtium
Roegentium
Copernicium
Ununtrium
Flerovium
Ununpentium
Livermorium
Ununseptium
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
Lr
Rf
Db
Sg
Bh
Hs
Mt
Ds
Rg
Cn
Uut
Fl
Uup
Lv
Uus
Uuo
(262)
---
(266)
---
(264)
---
(269)
---
(268)
---
(271)
(272)
---
(277)
---
(284)
---
(289)
---
(288)
---
(293)
---
(294)
---
Ytterbium
(262)
---
(261)
---
---
Lanthanum
Cerium
Praseodymium
Neodymium
Promethium
Samarium
Europium
Gadolinium
Terbium
Dysprosium
Holmium
Erbium
Thulium
57
58
59
60
61
62
63
64
65
66
67
68
69
70
La
Ce
Pr
Nd
Pm
Sm
Eu
Gd
Tb
Dy
Ho
Er
Tm
Yb
138.91
1.1
140.12
1.1
140.91
1.1
144.24
1.1
150.36
1.2
151.97
1.1
158.93
1.1
162.50
1.2
164.93
1.2
167.26
1.2
Actinium
Thorium
Protactinium
Uranium
Neptunium
Plutonium
Americium
Curium
Berkelium
Californium
Einsteinium
Fermium
89
90
91
92
93
94
95
96
97
98
99
100
101
102
Ac
Th
Pa
U
Np
Pu
Am
Cm
Bk
Cf
Es
Fm
Md
No
232.04
1.3
231.04
1.5
(237)
1.4
(244)
1.3
(243)
1.3
(247)
1.3
(247)
1.3
(252)
1.3
(257)
1.3
(258)
1.3
(259)
1.3
(227)
1.1
238.03
1.4
(145)
1.1
157.25
1.2
(251)
1.3
168.93
1.3
Mendelevium
173.04
1.1
Nobelium
(294)
---