Question

39. How can the valency of an element be determined if its electronic configuration is known? What will be the valency of an element of atomic number 9?

Answer 1

Part-1: Determination of valency

The valency of an element is determined by the number of electrons in its outer shell. As a result, the number of valence electrons derived from the element's electronic configuration yields valency, which is the number of electrons lost, gained, or shared by the element to attain the noble gas configuration.

Part-2: valency of an element of atomic number 9

Atomic number $=9$

So, electronic configuration = $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^5$

Valency $=8-7=1$

Thus, the valency of the element having atomic number 9 is 1