Question

What is the valency of Aluminium whose atomic number is 13 ? Give reason.

Answer 1

Aluminium has 13 electrons because it's atomic number is 13.So the first 2 electrons of those will be filled the first shell and the other 8 will be filled in second shell. Third shell has the capacity of 8 electrons and there are only 3 electrons left from aluminium fill. So 3 or 5 both can be taken as its valency.