1. What do all these images have in common?

2. The 4 images all contain “dipoles”, or two poles. BBBBattery: + and – ends MMMMagnet: two opposite ends EEEEarth: N and S poles WWWWater molecule: partial + and partial – ends (or sides) in the molecule

3. Dipole  An uneven distribution of electron density a molecule.  Results in a partial + and partial -.  Direction of dipole shown by arrow pointing toward negative end (cross on arrow near + end)

4. Polar Molecules  Molecules with a “net” or overall dipole.  Three steps in determining polarity:  Step 1: Lewis Dot (water)

5.  Step 2: Geometry  Bonding Regions? ___  Nonbonding Pairs? ___  Geometry is Bent or Angular

6.  Step 3: Examine three components of the molecule 1) Polar Bonds : EN difference between atoms

7. Polar vs. Nonpolar bonds

8. 2) Nonbonding (lone) Pairs on Central Atom (important when outside atoms are H)

9. 3) Symmetry of Molecule: If completely symmetrical, then NO overall or NET dipole

10. Symmetry of Molecule: - Must consider 3-D geometry to accurately judge symmetry

11. Sample Polarities Sample Polarities