Question

elements belonging to the same group have the same valency .give scientific reason.

Answer 1

Valence shell.Since valency depends upon the valence electrons so they have same valency. Elements in the same group have same valancy. This is because the elements have same number of valance electrons. These elements also have similar physical and chemical properties.

Answer 2

The electronic configuration of the outermost shell is the same for all the elements belonging to same group. So the number of valence electrons for all the elements in a group is the same. Therefore, the elements belonging to the same group have the same valency.