Question

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Answer 1

Concepts and reason

Hybridization is the concept of mixing atomic orbitals which have different shapes and energies to give an equal number (to that of mixed orbitals) of hybrid orbitals, which have the same energy and shape. By using this concept, molecular geometry and bond angles can be explained for molecules.

VSEPR theory: Valance Shell Electron Pair Repulsion Theory states that molecular geometry may alter due to the presence of repulsions between the lone pair electrons and the bonded pair of electrons present in the molecule.

Fundamentals

Hybridization of the molecules can be found by counting the number of groups surrounding the central atom of the molecule.

Groups surrounded by the central atom	Hybridization of the molecule	Molecular geometry
2	${\rm{sp}}$	linear
3	${\rm{s}}{{\rm{p}}^2}$	planar
4	${\rm{s}}{{\rm{p}}^3}$	tetrahedral
5	${\rm{s}}{{\rm{p}}^{\rm{3}}}{\rm{d}}$	Trigonal bi-pyramidal

A lone pair of electrons is also considered as a group.

According to the VSEPR theory, molecular geometry may change due to presence repulsions between bonded pair electrons and lone pair of electrons and they are arranged as follows..

${\rm{lone}}\,{\rm{pair}}\,{\rm{ - }}\,{\rm{lone}}\,{\rm{pair}}\,{\rm{ > }}\,{\rm{bond}}\,{\rm{pair}}\,{\rm{ - }}\,{\rm{lone}}\,{\rm{pair}}\,{\rm{ > }}\,{\rm{bond}}\,{\rm{pair}}\,{\rm{ - }}\,{\rm{bond}}\,{\rm{pair}}$

Given molecules

1. ${\rm{Xe}}{{\rm{F}}_{\rm{2}}}$

In the ${\rm{Xe}}{{\rm{F}}_{\rm{2}}}$ molecule, the central atom is ${\rm{Xe}}$ , and it is surrounded by two fluorine atoms and 3 lone pair of electrons. Therefore, the total number of groups surrounded by the ${\rm{Xe}}$ atom is 5. So, the hybridization of the molecules is ${\rm{s}}{{\rm{p}}^{\rm{3}}}{\rm{d}}$ .

2. ${\rm{BeC}}{{\rm{l}}_{\rm{2}}}$

In the ${\rm{BeC}}{{\rm{l}}_{\rm{2}}}$ molecule, the central atom is ${\rm{Be}}$ , and it is surrounded by two chlorine atoms. Therefore, the total number of groups surrounded by the ${\rm{Be}}$ atom is 2. So, the hybridization of the molecules is ${\rm{sp}}$ .

3. ${\rm{S}}{{\rm{F}}_{\rm{2}}}$

In the ${\rm{S}}{{\rm{F}}_{\rm{2}}}$ molecule, the central atom is ${\rm{S}}$ , and it is surrounded by two fluorine atoms and 2 lone pairs of electrons. Therefore, the total number of groups surrounded by ${\rm{S}}$ atom is 4. So, the hybridization of the molecules is ${\rm{s}}{{\rm{p}}^3}$ .

4. ${\rm{N}}{{\rm{O}}_{\rm{2}}}^{\rm{ - }}$

In the ${\rm{N}}{{\rm{O}}_{\rm{2}}}^{\rm{ - }}$ molecule, the central atom is ${\rm{N}}$ , and it is surrounded by two oxygen atoms and 1 lone pair of electrons. Therefore, total number of groups surrounded by ${\rm{N}}$ is 3. so the hybridization of the molecules is ${\rm{s}}{{\rm{p}}^2}$ .

1. ${\rm{Xe}}{{\rm{F}}_{\rm{2}}}$ has an ${\rm{s}}{{\rm{p}}^{\rm{3}}}{\rm{d}}$ hybridization and 3 lone pairs of electrons therefore, according to VSPER theory, the molecular geometry is linear.

2. ${\rm{BeC}}{{\rm{l}}_{\rm{2}}}$ has an ${\rm{sp}}$ hybridization and 0 lone pairs of electrons therefore, according to VSPER theory, the molecular geometry is linear.

3. ${\rm{S}}{{\rm{F}}_{\rm{2}}}$ has an ${\rm{s}}{{\rm{p}}^3}$ hybridization and 2 lone pairs of electrons therefore, according to VSPER theory, the molecular geometry is bent.

4. ${\rm{N}}{{\rm{O}}_{\rm{2}}}^{\rm{ - }}$ has an ${\rm{s}}{{\rm{p}}^2}$ hybridization and 1 lone pairs of electrons therefore, according to VSPER theory, the molecular geometry is planer.

Ans:

The linear molecules are

Answer 2

The geometry is very much affected by the bonding pairs and Lone pairs.

If Lone pair is on Central atom then it gives repulsion and hence bond agnle decreases. So the geomerty also changes from linear to "slightly bent" or "V shape".