Flourine( F2) and Chlorine(Cl2) are gases Bromine(Br2) is liquid and Iodine(I2)is solid even, all belong to halogen group
All F2, Cl2, Br2 and I2 belong to same halogen group, are non polar homo- diatomic molecules. Such molecules don't have permanent poles to generate dipole-dipole interaction. Existence of non polar molecules in liquid and solid state shows that they also have ability to create intermolecular forces and these intermolecular forces are London dispersion forces. Recall here Physical states ( solid, liquid and gas) are directly related to strength of intermolecular forces. Stronger the intermolecular forces , substance will be liquid or solid. Order of intermolecular forces in different physical states is Solids> liquid>gas London forces are weaker than dipole-dipole forces.To generate London forces, non polar molecules have to be polarized, the size of atoms decide the strength of London forces. Larger the molecules more will be the polarizibility - it is quantitative measurement of the extent to which the electronic cloud of non polar molecules can be polarized or disto...