Question

Which of the following statements is not correct for sigma and pi bond formed between two carbon atoms?

• A. Free rotation of atoms about a sigma bond is allowed but not in the case of pi - bond
• B. Sigma bond determines the direction between carbon atoms but a pi bond has no primary effect in this regard
• C. Sigma bond is stronger than a pi bond
• D. Bond energies of sigma and pi bonds are of the order of 264 kJ/mol and 347 kJ/mol respectively

Answer 1

The correct option is D Bond energies of sigma and pi bonds are of the order of 264 kJ/mol and 347 kJ/mol respectively

a) Sigma bonds are formed by the axial overlap of orbitals while pi bonds are formed by the sideways or lateral overlap of orbitals. Thus, free rotaion is allowed only for sigma bonds.

b) Sigma bond determines the direction between the carbon atoms beacuse, it is formed by the head on overlapping of the constituting atomic orbitals along the internuclear axis and pi bonds are only form by sideways overlapping of the orbitals.

c) The extent of overlapping is more in case of sigma bonds compared to pi bonds. Thus, a sigma bond is stronger than a pi bond.

d) This is not correct because sigma bonds will have a higher bond energy as sigma bonds are stronger than pi bonds.