In chemistry, valency is the power of an atom of an element to combine with other atoms measured by the number of electrons which an atom will give, take, or share to form a chemical compound. This is related to the number of spaces left in an atom's electron shells, which is why the only elements with valencies of zero are the noble gases.

See also: Chemical affinity, oxidation number, valency in linguistics

List of valencies for the first 103 elements in order of atomic number:


Atomic numberName of elementValency
1Hydrogen1
2Helium0
3Lithium1
4Beryllium2
5Boron3
6Carbon2, 4
7Nitrogen3, 5
8Oxygen2
9Fluorine1
10Neon0
11Sodium1
12Magnesium2
13Aluminium3
14Silicon4
15Phosphorus3, 5
16Sulfur2, 4, 6
17Chlorine1, 3, 5, 7
18Argon0
19Potassium1
20Calcium3, 5
21Scandium3
22Titanium3, 4
23Vanadium2, 3, 4, 5
24Chromium2, 3, 6
25Manganese2, 3, 4, 6, 7
26Iron2, 3
27Cobalt2, 3
28Nickel2, 3
29Copper1, 2
30Zinc2
31Gallium2, 3
32Germanium4
33Arsenic3, 5
34Selenium2, 4, 6
35Bromine1, 3, 5, 7
36Krypton0
37Rubidium1
38Strontium2
39Yttrium3
40Zirconium4
41Niobium3, 5
42Molybdenum2, 3, 4, 5, 6
43Technetium2, 3, 4, 6, 7
44Ruthenium3, 4, 6, 8
45Rhodium3, 4
46Palladium2, 4
47Silver1
48Cadmium2
49Indium1, 3
50Tin2, 4
51Antimony3, 5
52Tellurium2, 4, 6
53Iodine1, 3, 5, 7
54Xenon0
55Caesium1
56Barium2
57Lanthanum3
58Cerium3, 4
59Praseodymium3
60Neodymium3
61Promethium3
62Samarium2, 3
63Europium2, 3
64Gadolinium3
65Terbium3
66Dysprosium3
67Holmium3
68Erbium3
69Thulium2, 3
70Ytterbium2, 3
71Lutetium3
72Hafnium4
73Tantalum3, 5
74Tungsten2, 4, 5, 6
75Rhenium1, 4, 7
76Osmium2, 3, 4, 6, 8
77Iridium3, 4
78Platinum2, 4
79Gold1, 3
80Mercury1, 2
81Thallium1, 3
82Lead2, 4
83Bismuth3, 5
84Polonium2, 3, 4
85Astatine1, 3, 5, 7
86Radon0
87Francium1
88Radium2
89Actinium3
90Thorium4
91Protactinium4, 5
92Uranium3, 4, 5, 6
93Neptunium2, 3, 4, 5, 6
94Plutonium2, 3, 4, 5, 6
95Americium2, 3, 4, 5, 6
96Curium2, 3, 4
97Berkelium2, 3, 4
98Californium2, 3, 4
99Einsteinium2, 3
100Fermium2, 3
101Mendelevium2, 3
102Nobelium2, 3
103Lawrencium3
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