How will you find the valency of chlorine, sulphur and magnesium?

Q.:- How will you find the valency of chlorine, sulphur and magnesium?

 

Answer:-

Valency of an atom is the number of electrons gained, lost or shared so as to complete the octet of electrons in the valence shell.

Valency of chloride: It has electronic configuration = 2, 8, 7
Thus, one electron is gained to complete its octet and so its valency is 1.
Valency of sulphur: Its has electronic configuration = 2, 8, 6
Thus, 2 electrons are gained to complete its octet and hence its valency = 2
Valency of magnesium : It has electronic configuration = 2, 8, 2
Thus, it can lose two electrons to attain octet and hence its valency = 2