Question

Calcium is an element with the atomic number $20$.

(i) Will it be a metal or non-metal?
(ii) What will be its valency?
(iii) What would be the formula of its chloride?
(iv) Will it be smaller or larger than potassium?

Answer 1

The atomic no. of calcium is 20.

Electronic configuration $=2,8,8,2$

The valence electrons in calcium are $2$. Thus it is a metal of group $2$.

The valency of calcium is $+2$ as it has $2$ valence electrons.

The chloride of calcium is $Ca{Cl}_2$ as the valency of chloride ion is $-1$ and that of calcium is $+2$.

It is smaller than $K$ as both elements lie in the third period of the periodic table but $K$ lies to the left of $Ca$ in the period and we know that atomic size decreases as move right in a period.