1. Electronegativity

2. Ability of an atom to attract towards itself electrons in a chemical bond Electronegativity

3. Trend Most electronegative element!

5. Covalent Bond nonpolar equal sharing of electrons Electron density is symmetrical polar Unequal sharing of electrons Greater electron density near one element H—H

6. 6 H F F H electron rich region electron poor region e - riche - poor ++ --

7. 7 Covalent share e - Polar Covalent partial transfer of e - Ionic transfer e - Increasing difference in electronegativity Classification of bonds by difference in electronegativity DifferenceBond Type 0Covalent  2 Ionic 0 < and <2 Polar Covalent

8. For each bond, indicate the shift in electron density.

9. Practice Which of the following bonds is covalent, which is polar covalent, and which is ionic? a.The bond in CsCl b.The bond in H 2 S c.The NN bond in H 2 NNH 2