Van der Waals force

In chemistry, the van der Waals force is a type of intermolecular force that attracts molecules together. An intermolecular force is a relatively weak force between molecules. Van der Waals forces are the weakest type of intermolecular force. They are named after the Dutch scientist Johannes Diderik van der Waals (1837–1923).
Negatively charged electrons orbit around molecules or ions. The electrons shift their orbits to create slightly different charges from one end of the molecule to the other as a response to each other. These slight differences are called "partial charges", described by using the variables δ- or δ+. 
Van der Walls force is sometimes used loosely to mean for "all" intermolecular forces. Van der Waals forces are weaker than covalent bonds and usually weaker than hydrogen bonds, but they play a important role in supramolecular chemistry, enzymes, polymer science, nanotechnology, surface science, and condensed matter physics. Van der Waals forces define many properties of organic compounds, including their ability to dissolve.