1. Intermolecular Forces May the Force be with you, Or not??

2. Intermolecular Forces are…? Forces of attraction between molecules Forces of attraction between molecules Profoundly affect the physical and chemical properties of covalent/molecular substances… Profoundly affect the physical and chemical properties of covalent/molecular substances…

3. Dipole – Dipole forces Consider the distribution of negative charge around an BrF molecule? Consider the distribution of negative charge around an BrF molecule? (σ +) Br  F ( σ -) (σ +) Br  F ( σ -) This is a polar molecule This is a polar molecule

5. Dipole - Dipole Forces Forces of attraction between polar molecules (dipoles). Forces of attraction between polar molecules (dipoles).

6. Hydrogen Bonding A hydrogen atom that is bonded to a highly electronegative atom is attracted to an unshared pair of electrons on another highly electronegative atom. A hydrogen atom that is bonded to a highly electronegative atom is attracted to an unshared pair of electrons on another highly electronegative atom. Ouch that hurts my brain…how about a picture? Ouch that hurts my brain…how about a picture? Ok, draw a correct Lewis diagram of H 2 O show the geometry? Ok, draw a correct Lewis diagram of H 2 O show the geometry?

7. Polar Molecule ! Hydrogen bonded to highly electronegative atom Hydrogen bonded to highly electronegative atom Unshared pair on highly electronegative atom Unshared pair on highly electronegative atom

10. London Dispersion Forces

11. Make a Lewis diagram of Br2 Is this polar/non-polar? Can this molecule have hydrogen bonding or dipole-dipole forces? Are the electrons stationary or do they move?

12. Intermolecular attraction that result from the random motion of electrons and the creation of instantaneous dipoles. Intermolecular attraction that result from the random motion of electrons and the creation of instantaneous dipoles.

14. Which force do you think is the strongest?, the weakest? A. London dispersion B. Dipole – Dipole C. Hydrogen bonding

15. How do you think these forces might effect boiling point and other physical properties? Stronger forces Stronger forces Higher B.P., M.P. Hydrogen bonds are very important to the chemistry of living things. Hydrogen bonds are very important to the chemistry of living things. The intermolecular forces and shapes of the molecules determines the shapes and properties of crystals. The intermolecular forces and shapes of the molecules determines the shapes and properties of crystals.