1. Polarity and Intermolecular Forces Mr. Krstovic
CHEMSITRY 11
Polarity and Intermolecular Forces
Mr. Krstovic

2. Polar and nonpolar covalent bonds

3. Nonpolar - EQUAL sharing of e-
Polar - UNEQUAL sharing of e-
Use E.N. values to predict polarity between two atoms
0 – 0.7 nonpolar
0.7 – 1.7 polar
1.7 + ionic

4. Guidelines for Polar Molecules
Usually any diatomic compounds (HCl, HBr, CO)
Any molecules with OH at one end (CH3OH)
Any molecules with O at one end (OCl2)
Any molecule with an N at one end (NH3)

5. Guidelines for Nonpolar molecules
All diatomic elements (Cl2, N2)
Most carbon compounds in the form of CxAy

6. Polar or Non-polar????
CH5N
CH4O
C2H2
NaCl HF
CO32-

7. Intermolecular Forces
Ionic and covalent bonds are INTRAmolecular forces
INTERmolecular forces are forces between molecules

8. Intermolecular Forces
Ion-dipole: an attractive force between ions from ionic compoounds and polar molecules (Example: NaCl in Water)

9. Dipole-dipole: an attractive force acting between all polar molecules (Example: between HCl molecules)

10. Hydrogen Bonding (A special Case of Dipole-Dipole)
A relatively strong force between a POSITIVE hydrogen atom of one molecule and a highly electronegative atom (F,O, or N) in another molecule.

11. L.D.: an attractive force acting between ALL molecules, including nonpolar molecules.