Chapter 11 | Intermolecular Forces

Intermolecular forces

Attractive forces between molecules

Intramolecular forces

Hold atoms together in a molecule

Measure of intermolecular force

• Boiling point

• Melting point

• Vaporization

• Fusion

• Sublimation

Dipole-Dipole Forces

Attractive forces between polar molecules

Hydrogen Bonding

Between the hydrogen atom in a polar F-H, O-H, or N-H bond and an electronegative O, N, or F atom

Have anomalously high boiling points (specific heat, heat of vaporization) and are more viscous

London Dispersion Forces

Attractive forces arise due to temporary dipoles induced in atoms or molecules

Polarizability

How easy the electron distribution in the atom or molecule can be distorted. Increases with number of electrons

Intermolecular force strength ranking

Ion-Ion > Ion-dipole > Hydrogen bond > Dipole-dipole > London dispersion

Surface Tension

Energy or work required to increase the surface area of a liquid

Viscosity

A liquids resistance to flow