Why does iodine have a higher boiling point than chlorine?

Iodine and chlorine are both in group 7 of the periodic table, iodine is further down than chlorine. When travelling down the periodic table the size of the atom increases due to the amount of electrons that reside within it. Since iodine is further down, it is bigger than chlorine and will have stronger intermolecular forces than chlorine which will require more energy to break. This results in iodine having a higher boiling point than chlorine.