1. IIIIII II. Molecular Geometry Ch. 9 – Molecular Structure

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

3. A. VSEPR Theory n Types of e - Pairs  Bonding pairs - form bonds  Lone pairs - nonbonding e - Lone pairs repel more strongly than bonding pairs!!!

4. A. VSEPR Theory n Lone pairs reduce the bond angle between atoms. Bond Angle

5. n Draw the Lewis Diagram. n Tally up e - pairs on central atom.  double/triple bonds = ONE pair n Shape is determined by the # of bonding pairs and lone pairs. Know the common shapes & their bond angles! B. Determining Molecular Shape

6. C. Common Molecular Shapes 2 total 2 bond 0 lone LINEAR 180° BeH 2

7. 3 total 3 bond 0 lone TRIGONAL PLANAR 120° BF 3 C. Common Molecular Shapes

8. 3 total 2 bond 1 lone BENT 104.5° SO 2

9. 4 total 4 bond 0 lone TETRAHEDRAL 109.5° CH 4 C. Common Molecular Shapes

10. 4 total 3 bond 1 lone TRIGONAL PYRAMIDAL 107° NH 3 C. Common Molecular Shapes

11. 4 total 2 bond 2 lone BENT 104.5° H2OH2O C. Common Molecular Shapes

12. 5 total 5 bond 0 lone TRIGONAL BIPYRAMIDAL 120°/90° PCl 5 C. Common Molecular Shapes

13. 6 total 6 bond 0 lone OCTAHEDRAL 90° SF 6 C. Common Molecular Shapes

14. n PF 3 4 total 3 bond 1 lone TRIGONAL PYRAMIDAL 107° F P F F D. Examples

15. n CO 2 O C O 2 total 2 bond 0 lone LINEAR 180° D. Examples

16. C. Bond Polarity n Electronegativity Trend  Increases up and to the right.

17. A. Dipole Moment n Direction of the polar bond in a molecule. n Arrow points toward the more e - neg atom. H Cl ++ --

18. B. Determining Molecular Polarity n Depends on:  dipole moments  molecular shape

19. B. Determining Molecular Polarity n Nonpolar Molecules  Dipole moments are symmetrical and cancel out. BF 3 F F F B

20. B. Determining Molecular Polarity n Polar Molecules  Dipole moments are asymmetrical and don’t cancel. net dipole moment H2OH2O H H O

21. CHCl 3 H Cl B. Determining Molecular Polarity n Therefore, polar molecules have...  asymmetrical shape (lone pairs) or  asymmetrical atoms net dipole moment

22. C. Bond Polarity n Most bonds are a blend of ionic and covalent characteristics. n Difference in electronegativity determines bond type.

23. EN Difference n 0.0 - 0.4 Nonpolar n 0.4 - 1.0 Moderately Polar Covalent n 1.0 - 2.0 Very Polar Covalent n > 2.0 Ionic

24. C. Bond Polarity Examples: n Cl 2 n HCl n NaCl 3.0-3.0=0.0 Nonpolar 3.0-2.1=0.9 Moderately Polar Covalent 3.0-0.9=2.1 Ionic

25. C. Bond Polarity n Electronegativity  Attraction an atom has for a shared pair of electrons.  higher e - neg atom   -  lower e - neg atom   + ____

26. n Nonpolar Covalent Bond  e - are shared equally  symmetrical e - density  usually identical atoms C. Bond Polarity

27. ++ -- n Polar Covalent Bond  e - are shared unequally  asymmetrical e - density  results in partial charges (dipole)

28. n Nonpolar n Polar n Ionic View Bonding Animations.Bonding Animations C. Bond Polarity