What is valency ? Write short note on different types of valencies of cations with examples.

Explanation

Valency : The number of electrons gained or lost by an atom of an element for attaining stable octet or duplet connfiguration is called valency.
When an atom loses one or more electrons , the number of protons in it becomes more than the number of electrons and hence the ions formed are left with positive charge . this is called positive valency.
When an atom attains stability by gaining one or more electrons, the number of electrons in it becomes more than the number of protins and hence the ion formed becomes negatively charged. this is called negative valency.
The charge on the ion is corresponding to the number of electrons lost or gained . they may be monovalent , bivalent , trivalent and tetravalent which correspond to valencies , 1, 2, 3, 4 respectively.