The van der Waals forces named after the Dutch physicist Johannes van der Waals, who first described them in 1873.
They are forces which are developed between the atoms inside molecules and keep them together. The basis of these forces is the known in physics electrostatic forces (or coulomb forces). Van der Waals forces are exclusively internal forces of the molecule (forces within the molecule). Without these forces the molecule would have split. In some molecules these forces are not very strong, therefore these molecules are not very stable and it is relatively easy to break into smaller pieces or break and bind to other molecules or elements.
Attention: van der Waals forces should not be confused with nuclear forces. The nuclear forces are very strong forces that hold together the pieces that form the nucleus of an atom that protons and neutrons together.
Van der Waals forces keep the atoms of the chemical elements and chemical compounds together.
Examples: in carbon dioxide (CO2), there are 2 kinds of forces.
A) The atoms of carbon are kept together with the atoms of oxygen forming the molecule of carbon dioxide with forces van der Waals.
B) Inside the atom of the carbon (and inside the atom of the oxygen) protons and neutrons are kept together inside the nucleus with nuclear forces.
In the oxygen O2 Molecule
A) the 2 atoms of oxygen are held inside the oxygen molecule with van der Waals forces
B) inside the oxygen atom protons and neutrons are held in the nucleus with nuclear forces.