1. Intermolecular Forces
Chapter 16

2. Intermolecular
Intermolecular: Forces between molecules.

3. Dispersion Forces (aka: London forces, Van der Waals)
The weakest attraction.
Nonpolar molecules
Caused by the motion of electrons
Examples: Ar, C8H18 ,halogen diatomic molecules
Strength increases as the # of electrons increases

4. Dipole-Dipole Forces:
-polar molecules
-molecules with dipoles orient themselves so that “+” and “” ends of the dipoles are close to each other.

5. Hydrogen Bonds: dipole-dipole attraction in which hydrogen is bound to a highly electronegative atom. (F, O, N)

6. Which molecules have H-bonding?
NH3
CF4 HF

7. Explain the Difference:
H2O
Bp = 100°C
H2S
Bp = -60.7°C

8. Network Solids
Solids in which all of the atoms are covalently bonded to each other
Examples: diamond, graphite

10. Examples of three types of crystalline solids. (a) An atomic solid
Examples of three types of crystalline solids. (a) An atomic solid. (b) An ionic solid. (c) A molecular solid.