A permanent dipole distorts a nonpolar molecule's electron cloud, creating attraction.
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A dipole-induced dipole force occurs when the permanent dipole of a polar molecule distorts the electron cloud of a nearby nonpolar molecule, creating a temporary induced dipole. The induced dipole is always attracted to the permanent dipole, so the interaction is attractive whatever the orientation. The strength depends on the polarizability of the nonpolar molecule and on the size of the permanent dipole. These forces are weaker than dipole-dipole forces or hydrogen bonding but contribute to the solubility of nonpolar gases in polar solvents. They are one of the three types of van der Waals forces.
Key ideas: Dipole-induced dipole attraction scales with the polarizability of the nonpolar partner and with dipole squared: energy is proportional to alpha times mu squared over r to the sixth. Explains why gas solubility in water rises with size: Xe dissolves much more than He. It is the Debye force of the three Keesom, Debye and London contributions.
Common mistakes and connections: Students confuse it with dipole-dipole, thinking both molecules have permanent dipoles, or consider it negligible compared with other forces. In water, it is minor but real. Also the induced dipole follows the permanent dipole instantly, unlike orientational forces that depend on temperature. Links to polarizability, gas solubility, London forces and van der Waals forces.
Solubility of noble gases in water rises with polarizability, as the water dipole induces a dipole in larger, more easily distorted atoms. The interactive lesson shows this as a live animation or chart.
Oxygen gas dissolves slightly in water partly because the dipole of water induces a dipole in O2 molecules.
A permanent dipole distorts a nonpolar molecule's electron cloud, creating attraction.
Dipole-Induced Dipole Forces is a intermediate topic in Bonding & Molecular Structure. It builds on the vocabulary of beginner topics in this area.
Study these earlier topics in Bonding & Molecular Structure first: Dipole-Dipole Forces, Hydrogen Bonding, Ion-Dipole Forces.
The next topics in Bonding & Molecular Structure are Boiling Point and Intermolecular Forces and Intramolecular Hydrogen Bonding.
Yes. The interactive lesson includes a self-check question on Dipole-Induced Dipole Forces, and the Bonding & Molecular Structure quiz draws on every topic in this area.
Dipole-Induced Dipole Forces is topic 75 of 104 in Bonding & Molecular Structure.