CBSE Class 9 Answered

In physical chemistry, the van der Waals force is the sum of the attractive or repulsive forces between molecules (or between parts of the same molecule) other than those due to covalent bonds or to the electrostatic interaction of ions with one another or with neutral molecules.

The term includes:

• force between two permanent dipoles (Van der Waals-Keesom force)
• force between a permanent dipole and a corresponding induced dipole (Van der Waals-Debye force)
• force between two instantaneously induced dipoles (London dispersion force or Van der Waals-London force)

Van der Waals forces include attractions between atoms, molecules, and surfaces. They differ from covalent and ionic bonding in that they are caused by correlations in the fluctuating polarizations of nearby particles.