i) Instantaneous dipole - induced dipole
The induced dipole is constituted by the non-gravitational attraction that occurs in all molecules and is the only type of attraction between nonpolar molecules. The electrons are evenly distributed and there is no formation of an electric dipole. However, when nonpolar molecules approach each other, they induce the formation of temporary dipoles. In solid and liquid physical states, the molecules are so close that an instantaneous deformation of the electronic clouds is formed and positive and negative poles are created.
ii) Permanent dipole - permanent dipole
The dipole-dipole occurs between the molecules of polar compounds and is considered an intermediate force interaction. The electrons are distributed asymmetrically and so the more electronegative element attracts the electrons towards itself. In dipole-dipole bonds, polar molecules interact in such a way that opposite poles are preserved.
iii) Hydrogen bonds
The bond or hydrogen bond occurs in polar molecules that have hydrogen joined to electronegative elements and with low atomic volume, such as oxygen (O), fluorine (F) and nitrogen (N). It is the strongest intermolecular force, as there is a large difference in electronegativity between the elements. An example of hydrogen bonding occurs in the water molecule (H2O) in both solid and liquid states.
