Question

Calculate the valency of sulphur.

Answer 1

Part 1: Valency:

Valency is the combining capacity of the atom of an element or radical with the atoms of other elements or radicals.

Each atom of an element has a tendency to gain or lose electrons in order to get the stable outermost shell configuration(i.e. complete its octet).

Thus to calculate valency

• count the number of electrons in the outermost shell of the atom of an element if it is less than or equal to 4, then the valency remains equal to the number of electrons present in the valence shell.
• if the number of electrons in the outermost shell of the atom of an element is more than 4, then the valency of that element is calculated by subtracting the valence shell electrons from 8.

Part 2: Valency of Sulphur:

The atomic number of Sulphur $\left(\mathrm{S}\right)=16$

Electronic configuration$1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^4$.

There are six electrons in the outermost shell i.e. is more than 4 so valency can be calculated by the following formula:

Valency=(8-valency electrons)

valency of sulphur = (8-6)=2

valency of sulfur =2

Thus Sulphur requires two more electrons in order to complete its octet, hence its valency is 2.