Van der Waals dispersion forces

The van der Waals dispersion force is a category of intermolecular forces. This force is present between all atoms and molecules, although to various extents. The reason these forces are always present is the nature of electron clouds.

When an electron cloud is wobbling around its atom or molecule, the charge will distribute unevenly. Temporarily, the atom or molecule is more negative on one side over the other. This fluctuation creates a temporary dipole, which, in turn, will cause the electron clouds of nearby molecules or atoms to create dipoles as well. This synchronization of electron cloud movements generates a short-lived yet often significant attraction, known as the van der Waals dispersion forces.

Atoms are rarely alone, so it is safe to say van der Waals dispersion forces are all around us, such as in halogens, in the air we breathe, and the water we drink.

Figure 1: Image showing how temporary dipoles interact to create van der Waals dispersion forces.