Intermolecular forces can be defined as the distance-dependent forces of attraction (and also the forces of repulsion) that arise between atoms, molecules, and ions that are interacting with each other. The important types of intermolecular forces are – London dispersion forces, dipole-dipole forces, dipole-induced dipole forces, and hydrogen bonds. London dispersion forces arise due to the formation of a temporary dipole due to shifts in electron densities. These instantaneous dipoles induce the formation of a dipole in another atom or molecule.
Dipole-dipole forces are the strongest type of intermolecular forces that arise due to the electrostatic interactions between two or more dipoles. Dipole-induced dipole forces arise due to the interactions between a dipole and an uncharge atom/molecule. The interaction with the dipole induces the formation of a dipole in the uncharged species. Finally, hydrogen bonds can be considered as a special type of dipole-dipole interaction in which the differences in the electronegativities of hydrogen and another atom bound to it results in the permanent polarization of the bond.