Question

What is the valency of magnesium and chlorine in magnesium chloride?

Answer 1

Valency:

• “Valency is the combining capacity of an atom.”
• “The electrons present in the outermost shell of an atom are known as the valence electrons.”

The valency of magnesium and chlorine in magnesium chloride:

• Magnesium contains two valence electrons in its outermost shell as indicated by its electrical configuration of $\left[\mathrm{Ne}\right]3{\mathrm{s}}^2$, which can also be represented as 2,8,2.
• Chlorine has seven valence electrons in its outermost shell as indicated by its electrical configuration of $\left[\mathrm{Ne}\right]3{\mathrm{s}}^{2}3{\mathrm{p}}^5$, which can also be represented as 2,8,7.
• The valency can be determined as follows if the valence electron number is more than four.
• $\mathrm{Valency}=\mathrm{Valence}\mathrm{electron}-8$
• As a result, chlorine has a valency of $7-8$ which is $-1$.
• In ${\mathrm{MgCl}}_2$, the valency of magnesium is 2, whereas it is -1 for chlorine.