Which species has maximum number of lone pair?

Which species has the maximum number of lone pairs of electrons on the central atom?

(a) ClO₃^– (b) XeF₄ (c) SF₄ (d) I₃^–

First of all, let’s discuss the term lone pair, hybridisation and bond pair

What is lone pair?

What is Hybridisation?

Hybridisation is the concept of mixing atomic orbitals to form new hybrid orbitals, with different energies, shapes, etc., than the component atomic orbitals, suitable for the pairing of electrons to form chemical bonds in valence bond theory.

What is bond pair?

A bond pair is a pair of electrons that are in a bond. A single bond is always composed of two electrons that are paired with each other. These two electrons together are called the bond pair. Bond pairs can be seen in covalent compounds and coordination compounds.

What is the formula used?

X = ^(V+M-C+A)/₂

where V is valence electron of central atom, M is monovalent atoms, C is cation and A is anion.

Value of X indicates the hybridisation.

If X = 2, it represents sp hybridisation.

If X = 3, it represents sp² hybridisation.

If X = 4, it represents sp³ hybridisation.

If X = 5, it represents sp³d hybridisation.

If X = 6, it represents sp³d² hybridisation.

If X = 7, it represents sp³d³ hybridisation.

Calculate value of X for each option

(a) V=7, M=0, C=0, A=1

So, ^(7+0-0+1)/₂ = 4, indicates sp³ hybridisation.

Bond pair = 3 and Lone pair = 1

(b) V=8, M=4, C=0, A=0

So, ^(8+4-0+0)/₂ = 6, indicates sp³d² hydridisation

Bond pair = 4 and Lone pair = 2

(c) V=6, M=4, C=0, A=0

So, ^(6+4-0+0)/₂ = 5, indicates sp³d hybridisation.

Bond pair = 4, Lone pair = 1

(d) V=7, M=2, C=0, A=1

So, ^(7+2-0+1)/₂ = 5, indicates sp³d hydridisation

Bond pair = 2, Lone pair = 3

Structures of the given compounds are show below:

Maximum number of lone pair is in I₃^–, i.e., 3.

So, the correct option is D.

Read More: Which is more basic in nature? Benzyl amine or aniline.

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