Question

Which of the following possess the highest bond energy ?

• A. F2
• B. Cl2
• C. Br2
• D. I2

Answer 1

Answer: (B)

Cl2

Answer 2

The X-X bond disassociation enthalpies from chlorine onwards show the expected trend : Cl – Cl > Br – Br > F – F > I – I. The reason for the smaller enthalpy of dissociation of F2 is the relatively larger electrons-electrons repulsion among the lone pairs in F2 molecule where they are much closer to each other than in case of Cl2.