London dispersion force, also known as dispersion force, is a type of intermolecular force that occurs between non-polar molecules. It is caused by the temporary, instantaneous dipoles that are formed when electrons within the molecules are not evenly distributed.
These temporary dipoles induce similar dipoles in neighboring molecules, which attract each other and cause a weak attractive force between the molecules. This force is named after the German-American physicist Fritz London, who first described it in the 1930s.
London dispersion force is the weakest type of intermolecular force and is only significant when molecules are very close together. However, it can play an important role in determining the physical properties of substances, such as boiling points, melting points, and viscosity.