Chemistry - Complete Pblock- Question with Solution | TestHub

Bond dissociation energy of halogen family decreases down the group as the size of atom increases. The decreasing order for the bond dissociation enthalpy of halogen molecules is ${\mathrm{Cl}}_2(57\mathrm{kcal}/\mathrm{mol})>{\mathrm{Br}}_2(45.5\mathrm{kcal}/$ $\mathrm{mol})>{\mathrm{F}}_2(38\mathrm{kcal}/\mathrm{mol})>{\mathrm{I}}_2(35.6$ $\mathrm{kcal}/\mathrm{mol}$ ). A Caution A halogen molecule having larger atoms should have low dissociation energy and vice versa. Fluorine is an exception because of interelectronic repulsion is present in small atom of fluorine