1. Polarity

2. What is electronegativity?

3. Review: Bond Types Ionic – transfer of electrons
EN difference of greater than 1.7

4. Review: Bond Types Covalent – sharing of electrons
Nonpolar: electrons shared evenly
Two of the same atoms bonded together
EN difference of close to 0 (less than 0.4)
Polar: electrons shared unevenly
EN difference of less than 1.7
More EN element attracts electrons more

5. Polar vs. Nonpolar BondsCO F2

6. Polar vs. Nonpolar Bonds
H2O N2

7. Which bond is more polar?
C-O or C-F ?
Al-Cl or Br-Br ?
S-Cl or Si-H ?
H-Se or H-Te ?

8. Polarity of Molecules It's all about the symmetry
If the molecule is symmetrical all the way around, it is nonpolar
If it is asymmetrical (uneven) in any way, it is polar

9. SNAP Polarity of Molecules
Symmetrical = Nonpolar, Asymmetrical = Polar

11. Symmetry

12. WATER IS POLAR

13. CH4 CH3Br CH2Br2

14. AlCl3

15. O2

16. H2Te

17. CO CO2 For each: Draw Lewis structure Are bonds polar or nonpolar?
Is molecule polar or nonpolar?

18. Polarity of Bonds and Molecules
Bond polarity: look at EN difference (END)
Molecule polarity: look at symmetry
A nonpolar molecule can have polar bonds
A polar molecule can have nonpolar bonds, but this is rare (example: ozone)