The bond dissociation energy of fluorine is however, lower than chlorine and bromine due to its small size its inter electronic repulsion is very high . That's why the the bond dissociation enthalpy follows the order Cl2 >Br2>F2>I2

Bond energy is the amount of energy required to break a chemical bond. It is often measured in units of kilojoules per mole. The higher the bond energy, the stronger the bond.


The bond energy of Cl2 is 242 kJ/mol. Chlorine gas is a diatomic molecule, meaning it is made up of two chlorine atoms. The bond between these two atoms is relatively strong, which is why chlorine gas is a stable compound.


The bond energy of Br2 is 193 kJ/mol. Bromine gas is also a diatomic molecule, made up of two bromine atoms. The bond between these two atoms is weaker than the bond in chlorine gas because their atomic radii are larger, causing the bond to be longer and weaker.


The bond energy of F2 is 158 kJ/mol. Fluorine gas is also a diatomic molecule, made up of two fluorine atoms. The bond between these two atoms is the strongest of all the halogens because fluorine is the smallest halogen, causing the bond to be shorter and stronger.


The bond energy of I2 is 151 kJ/mol. Iodine gas is also a diatomic molecule, made up of two iodine atoms. The bond between these two atoms is the weakest of all the halogens because iodine is the largest halogen, causing the bond to be longer and weaker.


In summary, the bond energy of Cl2 is the highest among the halogens due to its small atomic radius, followed by Br2, F2, and I2 in decreasing order. The bond energy is directly related to the strength of the bond and the stability of the compound.