Question

Why Na element of group 1 and Cl element of group 17 both have a valency 1?

Answer 1

HEYA!

Na is a metal whereas Cl is a non metal .

The metal and non- metals are divided by semi- metals group.

At left , Metals lies and at right , non - metals reside.

Hence, Na and Cl are placed in different groups!


Hope it helps!