1. Intermolecular Forces

2. Intramolecular Forces:
The attractive forces between atoms and ions within a molecule
e.g Ionic bond, covalent bonds (double and triple bonds)
Strong
Intermolecular Forces:
The attractive forces between molecules
E.g. Van der Waals forces (London dispersion forces, dipole-dipole forces), hydrogen bonds
Weak (in comparison to intramolecular forces)
I.e. much less energy to melt H2O (inter) than for it to decompose into H2 and O2 (intra)

3. Intermolecular Forces
If covalent bonds were the only forces at work, most molecular compounds would be gases as there would be no attraction between molecules strong enough to group the molecules as liquids or solids

4. van der Waals Forces
Dipole-dipole
London Dispersion

5. Dipole-dipole
Forces of attraction between oppositely charged ends of polar molecules.

6. London Dispersion
Attractive forces between all molecules, including nonpolar molecules
Result of temporary displacements of the electron cloud around atoms in a molecule (extremely short-lived dipoles)
Therefore weaker than dipole-dipole

7. Hydrogen Bonding
Strong dipole-dipole force between the positive H atom of one molecule and a highly electronegative atom of another molecule

8. Practice Problems
p. 88 #7-12