1. Intermolecular Forces,

2. IntRAmolecular Forces
Intramolecular Forces (as you recall) were the forces between the atoms IN a molecular, or the bond strength.
Remember – Ionic Bonds have high melting points, Covalent bonds have low melting points etc.

3. Bond Polarity and Dipole Moments
A dipole moment results when a polar molecule has a center of positive charge separate from a center of negative charge

4. Bond Polarity and Dipole Moments
Water molecule dipole moment

5. Bond Polarity and Dipole Moments
The polarity of water affects its properties
Permits ionic compounds to dissolve in it
Causes water to remain liquid at higher temperature (boiling point is elevated)

6. Polar compounds dissolve in polar liquids
“Like Dissolves Like”
Polar compounds dissolve in polar liquids
Non-polar compounds dissolve in non-polar liquids
Like Dissolves Like Video

7. Intermolecular Forces
Glue that holds matter together
Melting and boiling points measure the relative strength
Ionic forces – strongest
Found in salts
NaCl melts at 800°C
Chapter 5

8. Intermolecular Forces
Dipole- Dipole (strongest)
Hydrogen Bonding
London Dispersion
Chapter 6

9. Dipole- Dipole
Strong forces of attraction between the positive and negative regions of molecules
Between polar molecules
BrF
Chapter 6

10. Hydrogen Bonds
Hydrogen atom is bonded to a highly electronegative atom (F, N, O)
Forces between water molecules
Chapter 6

11. London dispersion forces
Weak intermolecular forces
Instantaneous and induced dipoles
Caused by electrons moving around in atom
Important with non-polar molecules
Chapter 6

12. Intermolecular Forces
The attractions between molecules are not nearly as strong as the intramolecular attractions that hold compounds together.

13. Intermolecular Forces
They are, however, strong enough to control physical properties such as boiling and melting points, vapor pressures, and viscosities.

14. Intermolecular Forces
These intermolecular forces as a group are referred to as van der Waals forces.

15. van der Waals Forces Dipole-dipole interactions Hydrogen bonding
London dispersion forces

16. Metallic Solids
Metals are not covalently bonded, but the attractions between atoms are too strong to be van der Waals forces.
In metals, valence electrons are delocalized throughout the solid.