1. Polarity
How does electronegativity affect the polarity of a covalent bond?
How does the shape of a molecule affect the polarity of a molecule?

2. Polarity Uneven sharing of electrons. Within a covalent bond
Within an overall molecule
A molecule can have polar bonds but be nonpolar.
A molecule can have polar bonds and be polar.
A molecule cannot have nonpolar bonds and be polar!

3. Bond Polarity
Based on difference in electronegativity between atoms in a bond!

4. Which bonds are polar covalent?
C—C
C—H
C—O
N—F
Na—Cl

5. Most electronegative elements:
N, O, F

6. Polarity is not the whole story…

7. Just because bonds are polar…doesn’t mean molecule is polar!

8. How about CH4, CH2Cl2, CH3Cl?

9. Practice:
In your notebook, draw Lewis structures for the following. Identify individual bond polarities and overall polarity.
Remember, lone pairs attract electrons…so include lone pairs in your diagrams!
Make the models if it makes you feel more comfortable!
BCl3, SiO2, NF3, N2, CCl4,