London dispersion force

London Dispersion Force

Potential energy curve of an argon dimer, illustrating London dispersion forces.

The London dispersion force is a type of intermolecular force that arises from the interactions between induced dipoles in molecules. It is a component of the van der Waals forces and is present in all molecules, whether they are polar or nonpolar. These forces are named after the German-American physicist Fritz London, who first proposed their existence in 1930.

Origin

London dispersion forces originate from the temporary fluctuations in the electron distribution within atoms or molecules. These fluctuations create a temporary dipole moment, which can induce a dipole in a neighboring atom or molecule. The interaction between these temporary dipoles results in an attractive force.

Characteristics

London dispersion forces are generally weak compared to other types of intermolecular forces, such as hydrogen bonding or dipole-dipole interactions. However, they become significant in large atoms or molecules with many electrons, where the electron cloud is more easily polarizable.

Importance

Despite their relative weakness, London dispersion forces play a crucial role in the physical properties of substances. They contribute to the boiling points and melting points of nonpolar compounds and are responsible for the condensation of gases into liquids and solids.

Examples

London dispersion forces are the primary intermolecular forces in noble gases like argon, neon, and krypton. They also play a significant role in the properties of alkanes, alkenes, and other nonpolar organic compounds.

Related Pages

• Van der Waals force
• Intermolecular force
• Dipole-dipole interaction
• Hydrogen bond