Intermolecular Forces

Attractions that exist between individual molecules

Weaker than intramolecular forces (ionic, covalent, and metallic bonding) in a particular substance
Molecules with weak intermolecular forces holding them together can increase separation between each other and escape into the gas phase more easily and so have higher vapor pressures and lower boiling points

Three Main Types

London Dispersion Forces

Dipole-Dipole Interactions

Hydrogen Bonding

Weak forces of attraction experienced between all molecules
Generally the weakest type of intermolecular force
Occur when electrons experience temporary asymmetrical distribution in a molecule, resulting in momentary partial charges
Affect all molecules, even if they experience other intermolecular forces
Molecules with more electrons experience stronger London dispersion forces