Question

Why is chlorine's bond energy the biggest amongst these other compounds? Whats the reasoning behind this? Bond energies: Chlorine 240kj/mol Flourine 155kj/mol Bromine 190 kj/mol Iodine 149kj/mol

Answer 1

The bond dissociation energy is depends on the strength of bond. As going from top to bottom in groups atomic size of the atom is increases. If the size of the atom is more then less effective overlapping takes between the atomic orbitals.

The increasing order of bond dissociation energy of halogen bond is as follows:

I2 < Br2 < Cl2 > F2

Fluorine has less bond dissociation energy than chlorine this is due the small size of fluorine there is repulsive forces between non bonding electrons on fluorine atoms.

Therefore, chlorine bond dissociation energy is biggest among the halogen bonds.