What are the factors on which bond length depends?

a) Size of atoms – Bond length increases with the increase in size of the

atoms e.g. bond length between H & Cl in HCl = 127 pm whereas bond

length between C & Cl, C — Cl = 177 pm.

b) Nature of bonds – Bond length decreases with the multiplicity of

bonds because attractive forces between electrons and nuclei will

increase with the increase in number of shared electrons between

bonded atoms e.g. in C — C , bond length is 154 pm whereas in C ═ C

bond length is 134 pm.

3) Bond angle – As we know that the molecules formed by covalent bond are

oriented in a specific direction. As a result the atoms of these molecules

develop a bond angle.

The bond angle is defined as the average angle between the orbitals

containing bonding electron pairs around the central atom in a molecule. It is

expressed in degree / minute / second. It helps in determining the shape of

the molecules because it gives an idea about the distribution of orbitals

around the central atom in a molecule.