What is Valency?

Valency

Valency is the number of atoms of a particular element that is combined with one atom of another element to form a molecule. It is also known as molecular weight. It is a measure of the combining power of an atom.

The valency of an element is determined by the number of electrons in its outermost shell .The valency of an element can be increased either by giving or losing electrons.

Valency of a metal=No. of Valence electrons

Valency Of a non-metal=8-No. of valence electrons

For Example :

(1) Sodium (Z=11)

Electronic Configuration=2,8,1

Valency=1

(2) Magnesium (Z=2)

Electronic Configuration=2,8,2

Valency=2

There are some elements which do not combine with other elements.They are known as noble gases or inert gases.

For Example:

(1) Helium (Z=2)

Electronic Configuration=2

Valency=2

(2) Neon (Z=10)

Electronic Configuration=2,8

Valency=8