Question

How to calculate the valency of polyatomic ions?

Answer 1

Calculation of the valency of Poly-atomic ions

• Step 1: To identify the constituent elements in the poly-atomic ions.

1. Considering the example of Hydroxide ion (${\mathrm{OH}}^{-}$), the constituent elements in Hydroxide ion (${\mathrm{OH}}^{-}$) are Oxygen and Hydrogen.

• Step 2: To determine the valence electrons of each element present in the ion.

1. Electronic configuration of Oxygen (8) = 2,6
   Valence electrons of Oxygen = 6
2. Electronic configuration of Hydrogen(1) = 1
   Valence electrons of Hydrogen = 1

• Step 3: Calculate the total electrons of the ion.

1. Number of electrons of Oxygen = 6
   Number of electrons of Hydrogen = 1
   Charge on the Hydroxide ion = -1
2. Total number of electrons = 6 +1 +1
   Total number of electrons = 8

Hence, to calculate the valency of poly-atomic ions, we need to add up the total electrons of the constituent elements.