Bonding strength
The relative strengths of bonds are:
Covalent bonds > Hydrogen bonds > Permanent dipole interactions > London dispersion forces.
This can be shown by comparing two molecules with the same numbers of electrons.
Bromine atoms contain 35 electrons. Bromine exists as a diatomic molecule (Br2) and has 70 electrons in total.
Bromine molecules contain pure covalent bonds so are held together by London dispersion forces (temporary dipoles caused by momentary uneven sharing of electrons. Bromine is a liquid at room temperature (melting point -7掳C).
Iodine monochloride (ICl) is also a diatomic molecule with 70 electrons in total but contains a polar covalent bond. Since this molecule is a dipole it displays permanent dipole to permanent dipole interactions. It exists as a solid at room temperature (melting point 27掳C).