Intermolecular and Intramolecular forces

1. Intermolecular and Intramolecular forces

2. Intermolecular Forces between molecules Is what attracts molecules to each other Intramolecular Forces within the molecule Is what keeps a molecule together Intermolecular vs. Intramolecular

3. Intramolecular Forces • Metallic Bonds • Ionic bonding • Polar Covalent • Non-Polar Covalent In order of decreasing strength

4. Intermolecular Forces • Hydrogen Bonding • Dipole-Dipole Interactions • London Dispersion In order of decreasing strength

5. Dipole-Dipole • Attraction between polar molecules • Specifically between the + and – ends of polar molecules • Only polar molecules can have dipole-dipole interactions Negative End Positive end

6. Hydrogen Bonding • Special type of Dipole-Dipole interaction • Happens only with polar molecules containing hydrogen • Positive hydrogen bonds to negative sides of other polar molecules • Only happens when H is paired with with O, F, or N. • H2O, HF, NH3

7. Hydrogen Bonding • Hydrogen bonds are strong • Weaker than covalent bonds • Account for the high boiling point of water • Dipole-Dipole are relatively weak

8. London Dispersion Forces

9. London Dispersion Forces • London dispersion forces are created when one molecule with a temporarily dipole causes another to become temporarily polar. + − − + − +