The shape of molecule is the particular arrangement of electron pairs around the central atom. VSEPR stands for valence shell electron pair repulsion theory.

Shape of molecule containing bond pairs only

1. On the basis of VSEPR theory shape of molecule BeF2

In BeF2 molecule, Be is surrounded by 2 bond pairs with 2 F atoms. Bond pairs repel each other at the maximum distance. This is possible at an angle of 180 degree and forms linear shape.

2. On the basis of VSEPR theory shape of molecule BF3

In BF3, the central atom is B which has 3 valence electrons. It shares these 3 electrons with the 3 F atoms. The 3 bond pairs repel each other at the maximum distance and takes up the position an angle of 120 degree. Hence, the shape formed is triangular planar.

3. On the basis of VSEPR theory shape of molecule CH4

Central atom in CH4 is Carbon. It has 4 valence electrons which are shared with 4 H atoms. Thus, there are 4 bond pairs of electrons present around the central atom. The 4 bond pairs repel each other at the maximum distance and takes up the position an angle of 109.28 degree. Hence, the shape formed is tetrahedral.

4. On the basis of VSEPR theory shape of PCl5

1. In PCl5, Phosphorus has 5 valence electrons. It can form 5 bond pairs with 5 Cl atoms.
2. Apply the VSEPR theory, the bond pairs will occupy the position at a maximum distance from each other.
3. So, it acquires the trigonal bipyramidal shape.
4. 3 Cl will acquire the equatorial bonds. They are present at an angle of 120 degree from each other.
5. 2 Cl will take the axial position. They are present at an angle of 90 degree with the equatorial bonds.
6. Axial bonds are slightly longer than equatorial bonds and are therefore weaker.
7. This is due to greater repulsion on axial bond pair by equatorial bond pair.
8. All the 5 P-F are equivalent according to NMR studies.

5. On the basis of VSEPR theory shape of SF6 and IF7

Similarly, SF6 will acquire a regular octahedral geometry. IF7 will acquire the shape of pentagonal bipyramidal. In case of IF7, 5 equatorial I-F bonds are at an angle of 72 degree with each other. 2 axial I-F bonds makes an angle of 90 degree with the equatorial bonds. All the I-F bonds are not equivalent.

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