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

The definite combining capacity of the atoms of each element, wherein electrons are lost, gained or shared to make the octet of electrons present in the outermost shell is defined as valency. To measure valency, we can figure out the number of electrons that are required to complete the shell in which it is contained or losing excess electrons if present, once the filling is complete.

• 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.

## Valency of chlorine

The atomic number of chlorine is 17

• The electronic configuration of chlorine is [Ne]3s3p5or can also be written as 2,8,7.
• This shows chlorine has 7 valence electrons in its outermost shell.
• If the valence electron is more than 4, then the valency can be calculated as follows: Valency = Valence electron -8
• Accordingly, the valency of chlorine is 7-8 which is -1.

## Valency of sulphur

The atomic number of sulphur is 16

• The electronic configuration of sulfur is (S) [Ne] 3s.
• So in order to achieve stability, sulfur has to gain 2 electrons.
• The valency of sulphur = 8 – 6 = 2
• Therefore, the valency of sulphur is 2.

## Valency of magnesium

The atomic number of magnesium is 12

• The electronic configuration of magnesium is [Ne]3sor can also be written as 2,8,2.
• This shows magnesium has 2 valence electrons in its outermost shell.
• If the valence electron is less than 4, it is recognised as valency.
• As magnesium has 2 valence electrons, its valency is 2. (7) (1)