Respected mam/sir,

What is valency and kindly please give an example of it. 

Valency: 

 

The valency of an element is the number of hydrogen atoms that can combine with or replace (either directly or indirectly) one atom of the element.

In other words, the valency of an element is the number of electrons an atom of the element uses to combine with atoms of other elements - it is the combining power of an atom of the element.

In an atom, the valence electrons are the electrons that can be used in combining with other atoms - these are the electrons in the orbitals of the outermost shell (also called valence shell).

 

Example: H →1; Mg→2; Al→3; C→4; N→3, and 5; P→3 and 5; O→2; S→ 2, 4 and 6; Cl→ 1; and Ne→0.

The valencies of radicals are same as the number of charge they carry.

Example: NH₄⁺ → 1; OH^- → 1 ; and SO₄^2- → 2