London Dispersion Forces
| Formula / Notation | E_London = −C/r⁶; C ∝ α²I (polarisability α, ionisation energy I) |
|---|---|
| Also Known As | London forces, dispersion forces, instantaneous dipole-induced dipole, van der Waals dispersion |
What is London Dispersion Forces?
Weak, temporary attractive forces between all molecules arising from instantaneous fluctuations in electron distribution creating temporary dipoles. Also called van der Waals forces or induced dipole-induced dipole interactions. Strength increases with molecular size and surface area.
Formula & Notation
Other Names / Synonyms: London forces, dispersion forces, instantaneous dipole-induced dipole, van der Waals dispersion
Properties & Characteristics
Uses & Applications
Safety Information
Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.
Key Facts
Frequently Asked Questions
Weak, temporary attractive forces between all molecules arising from instantaneous fluctuations in electron distribution creating temporary dipoles. Also called van der Waals forces or induced dipole-induced dipole interactions. Strength increases with molecular size and surface area.
London dispersion forces explain: why noble gases liquefy (He: 4.2 K; Rn: 211 K — increasing London forces down Group 18), why alkanes have higher boiling points with increasing chain length, why octane (C₈H₁₈) is liquid at room temperature while methane (CH₄) is a gas, and adhesion in gecko feet (v…
No direct safety concern for the concept. The increasing London forces with molecular size explain why larger nonpolar organic molecules (high MW hydrocarbons, PCBs) are more persistent environmental contaminants — stronger IMF with soil organic matter reduces environmental mobility.
The formula or notation for London Dispersion Forces is: E_London = −C/r⁶; C ∝ α²I (polarisability α, ionisation energy I)