London

Definition

London dispersion forces are weak intermolecular forces arising from temporary shifts in electron density, creating instantaneous dipoles. They are present in all molecules but are the only intermolecular force in nonpolar molecules.

5 Must Know Facts For Your Next Test

1. London dispersion forces increase with larger molecular size and higher molar mass.
2. They are the weakest type of intermolecular force compared to dipole-dipole interactions and hydrogen bonds.
3. These forces contribute to the boiling and melting points of substances; stronger London dispersion forces result in higher boiling and melting points.
4. London dispersion forces arise due to momentary fluctuations in electron distribution, leading to temporary dipoles.
5. All atoms and molecules exhibit London dispersion forces, regardless of their polarity.

Review Questions

• How do London dispersion forces affect the boiling point of a substance?
• What causes London dispersion forces to arise between molecules?
• Why are London dispersion forces significant even in nonpolar molecules?

Related terms

Dipole-Dipole Interactions: Intermolecular forces occurring between polar molecules due to permanent dipoles.

Hydrogen Bonding: A strong type of dipole-dipole interaction occurring when hydrogen is bonded to highly electronegative atoms like oxygen, nitrogen, or fluorine.

Van der Waals Forces: A collective term for various intermolecular attractions, including London dispersion forces, dipole-dipole interactions, and hydrogen bonding.