Question

The electronic configuration of calcium is $2$, $8$, $8$, $2$ . Find the valency of the element ?
A. $1$
B. $2$
C. $3$
D. $4$

Answer 1

Hint: Valency is defined as the number of electrons required to be gained or removed by the element to complete its octet that is eight electrons in its outermost shell . By gaining eight electrons in the outermost shell any element gets stabilized and less reactive .

Complete step by step answer:
The element given in question is calcium and its electronic configuration is $2$, $8$, $8$, $2$.
Now , since it has two electrons in its outermost shell , so to achieve eight electron in its outermost shell this element has two options either by gaining six more electrons in its outermost shell to make its configuration $2$, $8$, $8$, $8$ or by losing two electrons from its valence shell to make its configuration $2$, $8$, $8$ . In both the cases the octet of elements is completed . But it would be much easier for this element to remove two electrons from its valence shell rather than gaining six more electrons in its outermost shell .
Hence this element will attain its octet by removing two electrons from its outermost shell and its configuration will be $2$, $8$, $8$ .
Since this element is removing or losing two electrons to gain its octet therefore its valency is $2$.

So, the correct answer is Option A .

Note:
The outermost shell in which electrons are present is known as valence shell of element . By completing octet in valence shell element becomes inert or less reactive and this configuration is known as inert gas configuration and valence electrons are the electrons in the outermost shell of an atom .