Question

How will you find the valency of chlorine($\mathrm{Cl}$), sulphur($\mathrm{S}$) and magnesium($\mathrm{Mg}$)?

Answer 1

Valency:

• The definite combining capacity of the atoms, wherein electrons are lost, gained or shared to make the octet of electrons is defined as valency.
• To measure valency, we have to find the number of electrons that are required to complete the valence shell.
• If the number of electrons in the outermost shell of the atom of an element is less than or equal to 4, then the valency of the element is equal to the number of electrons in the outermost shell.
• On the other hand, if the number of electrons in the outermost shell of the atom of an element is greater than 4, then the valency of that element is determined by subtracting the number of electrons in the outermost shell from 8.
• Chlorine($\mathrm{Cl}$) has 7 electrons in the outermost shell which is greater than 4, hence the valency of chlorine($\mathrm{Cl}$) is $8-7=1$.
• Sulphur($\mathrm{S}$) has 6 electrons in the outermost shell which is greater than 4, hence the valency of sulphur($\mathrm{S}$) is $8-6=2$.
• Magnesium($\mathrm{Mg}$) has 2 electrons in the outermost shell which is less than 4, hence the valency of magnesium($\mathrm{Mg}$) is 2.