The shape of a molecule is square planar. how many lone pairs of electrons are there on the central atom? [1] [2] [3] [4] 1 2 3 4 5

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 .

Formula used  :

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  molecules.

Bond pair electrons = 4

Lone pair electrons = 6 - 4 = 2

The number of electrons are 6 that means the hybridization will be 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

CO2 < CH3Br < CH3OH < RbF

Explanation:

The boiling point of the compounds can be determined in terms of the strength of the intermolecular forces present in each compound.

Intermolecular forces are weak forces joining non-polar and polar molecules together. We have London dispersion forces, dipole-dipole forces of attraction, and hydrogen bonding.

London dispersion forces are weak attractions found between non-polar and polar symmetrical molecules. They are the weakest of all the electrical forces and they act between atoms and molecules e.g CO2

The dipole-dipole attractions are forces of attraction existing between polar unsymmetrical molecules. The dipole-dipole force of attractions is much stronger than London dispersion forces but weaker than Hydrogen bonding. e.g  CH3Br

Hydrogen bonding is a special dipole-dipole attraction between polar molecules in which a hydrogen atom is directly joined to a highly electronegative atom (e.g. oxygen, nitrogen, or fluorine). Here, the bond in CH3OH is a hydrogen bond.

Ionic bonding is a bond that is formed between two kinds of atoms having a large electronegative difference such as in RbF,

Thus, in increasing order of boiling point;

CO2 < CH3Br < CH3OH < RbF