1. Intermolecular Forces
Unit 3: Bonding
Intermolecular Forces

2. Polarity and Solubility
“like dissolves like”
How do we explain this???

3. Intermolecular Forces
Intermolecular forces: weak and mostly temporary attractions between molecules
Need to know:
London dispersion forces (induced dipole)
Dipole-dipole forces
Hydrogen bonding forces
Ion-dipole forces

4. London Dispersion Forces
London Dispersion forces attract nonpolar molecules or atoms by temporary induced dipoles due to uneven electron distribution
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5. Dipole-Dipole Forces
Dipole-dipole forces attract polar molecules to one another
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6. Hydrogen Bonding Forces
Hydrogen Bonds: an interaction between a hydrogen and an O, N, or F atom (note that they are very electronegative atoms).
H-bonds raise boiling points
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7. Ion-Dipole Forces
Ion-Dipole forces attract an ion (+ or -) to a polar molecule
Example: Na+ and Cl- ions aligning themselves with dipoles of water molecule
Animation:
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8. Relative Strengths of Intermolecular Forces
London dispersion forces

9. Other Bond-Like Forces
A nice summary of intermolecular forces: