Factors affecting bond length :
(i) The bond length increases with increase in the size of the atoms. For example, bond length of H – X is in the order, HI > HBr > HCl > HF.
(ii) The bond length decreases with the multiplicity of the bond. Thus, bond length of carbon – carbon bonds is in the order, C ≡ C < C = C < C-C.
(iii) As an s-orbital is smaller in size, greater the s-character, shorter is the hybrid orbital and hence shorter is the bond length.
For example, sp3 (C – H) > sp2 (C = H) > sp (C ≡ H)
(iv) Polar bond length is usually smaller than the theoretical non-polar bond length.
