London dispersion force, also referred to as dispersion forces or van der Waals forces, is a weak intermolecular force that exists between all atoms and molecules. It is named after the German-American physicist Fritz London who first described this phenomenon in the 1930s. London dispersion forces arise due to temporary fluctuations in electron densities around atoms or molecules, resulting in the creation of instantaneous dipoles.
In any atom or molecule, electrons are not always evenly distributed. At any given moment, there may be a temporary imbalance in electron distribution, causing one part of the atom or molecule to have a slight positive charge and another part to have a slight negative charge. These temporary dipoles induce similar fluctuations in their neighboring atoms or molecules, resulting in an instantaneous dipole-dipole interaction.
London dispersion forces are typically weaker than other intermolecular forces, such as hydrogen bonding or dipole-dipole interactions. However, they play a crucial role in determining the physical properties of various substances, including boiling points, melting points, and volatility. The strength of London dispersion forces increases with an increase in the number of electrons and the size of the electron cloud in a molecule or atom.
Overall, London dispersion forces contribute to the attraction between particles and enable the formation and stability of condensed phases, such as solids and liquids. They are fundamental to our understanding of intermolecular interactions and are essential for explaining various phenomena in chemistry, physics, and materials science.
