Answer : The number of lone pairs of electrons present on the central atom are, 2
Explanation :
As we are given that the shape of molecule is square planar.
The square planar is a molecular shape that results when there are 4 bonds and 2 lone pairs present on the central atom in the molecule.
The example of a square planar molecule is, xenon tetrafluoride [tex](XeF_4)[/tex].
Formula used :
[tex]\text{Number of electrons}=\frac{1}{2}[V+N-C+A][/tex]
where,
V = number of valence electrons present in central atom
N = number of monovalent atoms bonded to central atom
C = charge of cation
A = charge of anion
Now we have to determine the hybridization of the [tex]XeF_4[/tex] molecules.
[tex]\text{Number of electrons}=\frac{1}{2}\times [8+4]=6[/tex]
Bond pair electrons = 4
Lone pair electrons = 6 - 4 = 2
The number of electrons are 6 that means the hybridization will be [tex]sp^3d^2[/tex] and the electronic geometry of the molecule will be octahedral.
But as there are four atoms around the central xenon atom, the fifth and sixth position will be occupied by lone pair of electrons. The repulsion between lone and bond pair of electrons is more and hence the molecular geometry will be square planar.
From this we conclude that, there are two lone pairs and 4 bond pairs are present on central atom.
Hence, the number of lone pairs of electrons present on the central atom are, 2
