dipoleinduced

Dipole-induced dipole interactions are a type of intermolecular force that occurs when a polar molecule with a permanent dipole moment approaches a nonpolar molecule or atom. The electric field generated by the permanent dipole polarizes the electron cloud of the nonpolar partner, inducing a temporary dipole there. The interaction between the permanent dipole and the induced dipole is attractive, contributing to the overall van der Waals forces present in many systems.

These forces are weaker than permanent dipole–dipole (Keesom) interactions but can be significant in mixtures where polar and nonpolar species coexist. The strength and distance dependence of dipole-induced dipole interactions are governed by the polarizability of the nonpolar molecule and the square of the permanent dipole moment. The interaction energy generally decreases rapidly with distance, roughly following a sixth-power dependence on separation, and is influenced by molecular orientation and thermal motion.

Common examples include a polar molecule such as HF or water influencing nearby nonpolar atoms or molecules like argon, nitrogen, or methane. In liquids and gases, dipole-induced dipole forces contribute to solubility behavior, gas solvation, and phase equilibria. They also affect spectroscopic properties by altering local environments around solutes.

Dipole-induced dipole interactions are distinct from ion-induced dipole interactions, where a charged species induces a dipole in a neutral molecule, and from London dispersion forces, which arise from instantaneous fluctuations in electron density within nonpolar species.