1. Types of Intermolecular Bonds

2. Van der Waals forces:
intermolecular forces of attraction Examples: London forces, dipole-dipole forces, hydrogen bonds

3. LONDON FORCES
London forces are weak because (1) partial charges are involved and (2) because they are temporary. They arise from the random movement of electrons in atoms and molecules.
a) small collection of nonpolar molecules
b) a nonpolar molecule may temporarily have a slight excess of electrons in one portion of the molecule
c) During the brief interval that these temporarily polar molecules exist, they are attracted to each other

4. Hydrogen bonds: strongest intermolecular bonds