2. Valence Shell Electron Pair Repulsion Theory –Electron pairs orient themselves in order to minimize repulsive forces.

3. Types of e - Pairs –Bonding pairs - form bonds –Lone pairs - nonbonding e - Lone pairs repel more strongly than bonding pairs!!!

4. Lone pairs reduce the bond angle between atoms. Bond Angle

5. Draw the Lewis Diagram. Tally up e - pairs on central atom. –double/triple bonds = ONE pair Shape is determined by the # of bonding pairs and lone pairs. Know the 7 common shapes

6. 2 bond pair of electrons 0 lone pair LINEAR 180° CO 2

7. 3 bond pair of electrons 0 lone pair TRIGONAL PLANAR 120° BCl 3

8. BENT <120° 2 bond pair of electrons 1 lone pair NO 2

9. TETRAHEDRAL 109.5° 4 bond pair of electrons 0 lone pair CH 4

10. TRIGONAL PYRAMIDAL 107° 3 bond pair of electrons 1 lone pair PCl 3

11. BENT 104.5° 2 bond pair of electrons 2 lone pair H2OH2O

12. TRIGONAL PYRAMIDAL F P F F 3 bond pair of electrons 1 lone pair

14. HC H H H in the plane of the drawing surface behind the drawing plane in front of the drawing plane

16. Polar molecules have one end that is slightly negative and one end that is slightly positive. A molecule with two poles is called a dipole, but not all molecules with polar bonds are dipoles.

17. Depends on: –dipole moments –molecular shape

18. Direction of the polar bond in a molecule. Arrow points toward the more e - neg atom. H Cl ++ --

19. Nonpolar Molecules –Dipole moments are symmetrical and cancel out. BF 3 F F F B

20. Polar Molecules –Dipole moments are asymmetrical and don’t cancel. net dipole moment H2OH2O H H O

21. CHCl 3 H Cl Therefore, polar molecules have... –asymmetrical shape (lone pairs) or –asymmetrical atoms net dipole moment

23. Practice  P.98 # 6 - 8

24. If the electronegativities are not equal then the bond will be polar. If the electronegativities are equal then the bond will be non-polar.

25. DifferenceType of bondExample 0.0 – 0.4covalent non-polar H - H 0.5 – 1.0covalent slightly polar H – Cl 1.1 – 2.0covalent very polar H - F > 2.1ionicNa - Cl Ionic bonds

27. Practice  P.100 # 9 - 11

28. When polar molecules are attracted to each other Electrostatic attractions occur between the opposite charged regions of molecular dipoles. Similar to ionic bonding but much weaker

29. Polar molecules have one end that is slightly negative and one end that is slightly positive. A molecule with two poles is called a dipole, but not all molecules with polar bonds are dipoles.

31. Practice  P.102 # 12 – 16 Section 3.3 Questions  P.104 # 1, 2, 4-6, 10