Van der Waals interactions are weak intermolecular forces arising from electrostatic interactions between neutral atoms and molecules. All molecules produce temporary charges. Due to the varying distribution of electrons, a higher electron density in one region of the electron cloud results in an instantaneous dipole or a temporary dipole. This subsequently induces another instantaneous dipole in the neighboring molecule. The domino effect of dipoles gives rise to weak intermolecular attractive forces, which exist between all molecules, whether polar or nonpolar. Dipoles in polar molecules like water electrostatically interact through dipole-dipole forces. Dipole-induced dipole forces occur when a polar molecule like water disturbs the electronic arrangement of a non-polar molecule like diatomic oxygen and induces a dipole. Instantaneous dipoles of any type of atom or molecule interact through weak London dispersion forces. These forces are attractive when the atoms are close enough for their electron clouds to just contact. If the atoms get any closer, these forces become repulsive.