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

ScienceClass 9CBSEAnswered 27 Mar 2026
Answer

Solution:

We know that an element’s valency refers to its proclivity for accepting or losing electrons in order to complete its octet and achieve a stable electronic state.

It is the smallest number of electrons that must be added or removed to entirely occupy an element’s outermost shell.

Mathematically, if an atom’s outermost shell contains 4 or fewer electrons, the element’s valency is equal to the number of electrons present in the outermost shell; if it contains more than 4, the valency is determined by subtracting the total number of electrons present in the outermost shell from 8.

Calculation of valency:

Valency of chlorine: 

The electronic configuration of chlorine = 2, 8, 7

Chlorine has 7 (more than 4) electrons in its outermost shell.

Therefore, the valency of chlorine = 8 – the number of electrons in the outermost shell

= 8−7

= 1

Valency of Sulphur: 

The electronic configuration of Sulphur = 2, 8,6

Sulphur has 6 (more than 4) electrons in its outermost shell.

Therefore, the valency of chlorine = 8 – the number of electrons in the outermost shell

= 8−6

= 2

Valency of magnesium: 

The electronic configuration of Magnesium = 2, 8, 2

Magnesium has 2 (less than 4) electrons in its outermost shell.

Therefore, the valency of magnesium= Number of electrons in its outermost shell

= 2

Science · Class 9