Valency n. : See Valence.

Valency n. : A unit of combining power; a so-called bond of affinity.

Example:
How to find the formula of a compound using the Valency number?

Taxonomy
valence, atoms, element, compounds, chemistry, bonds, valence bond theory, valence shell, particles, IUPAC, hydrogen, free encyclopedia, theory, combining power, combinations, tendency, Franklin, valency bonds.

Defination from the web:
valency or valency number, is a measure of the number of chemical bonds formed by the atoms of a given element. ... The exact inception, however, of the theory of chemical valencies can be traced to an 1852 paper by Edward Frankland, in which he combined the ...