Question

X is an element with atomic number $20$. What will be the valency of the element?

Answer 1

Valency:

Valency is defined as the combining capacity of the element. The valency of an element is determined by the number of valence electrons present in the outermost shell of its atom.

According to the question:

• The electronic configuration of the element X with atomic number 20 will be $2,8,8,2$.
• Since the element has just two electrons in its outermost shell, it can easily lose these electrons and can thereby attain a positive charge $+2$ which is its valency.
• In this way, it attains the nearest stable noble gas configuration.

Thus, the valency of the element becomes $+2$.