Question

what is the valence of Na and cl

Answer 1

Hlo





The Valency of Na is( 1 +)
As it has 11 electrons so it shares it one electrons to form it's last layer octet
The valency of Cl is ( 1-)
As it has 17 electrons so it has to gain 1 electrons to complete it octet shell.




Thanks

Answer 2

According to old theory, Valency of Na is +1,
Valency of Cl is -1

But now, number of electrons present in valence shell is regarded as Valency.

Hence, Valency of Na=1, Cl=1

We know that

Valency of metal's = Number of valence electrons.

Valency of Non metal is 8- Number of valence electrons.

As Na is a metal and have 1 valence electron, it's valency is 1.

As Cl is a non metal, and have 7 valence electrons.

it's valency =8-7=1