Question

What is ment by valency with exampels how do we explain to the students easily?

Answer 1

valency of an element is the combinig power of it with the another atoms...it is the most simple and easy way of explanation...
example:oxygen atomic no is 8 there it has 6 electrons in it outer shell therefor it needs only 2 more electron to complete its octate therefor it has a valency 2

Answer 2

The capacity of an element to combine with other element is called its valency it can also be defined as a number of electron given taken or shared by an atom during a chemical reaction for eg : sodium gives 1 electron and chlorine takes 1 electron  hence the valency of sodium and chlorine is 1.