1. Why are Intermolecular Forces Important? Intermolecular forces play a role in determining the physical properties of a substance (e.g.- melting point & solubility).

2. Types of Intermolecular Forces (Strongest to Weakest) I. H-bonds Found in polar substances where H is bonded to O, N, or F.

3. Importance of H-Bonds DNA replication & protein synthesis.

4. Transpiration-Cohesion Theory

5. Respirators

6. Density of Ice < Density of Water

7. II. Dipole-Dipole forces Found in polar substances where H is NOT bonded to O, N, or F.

8. III. London forces F ound in ALL molecular substances. London forces become stronger as molecular size increases. Therefore, candle wax (C 25 H 52 ) is a solid even though it is nonpolar & only has London forces.

9. The Effect of Intermolecular Forces on the Boiling Point of Molecular Compounds