1. Molecular Geometry VSEPR - Valence Shell Electron Pair Repulsion Theory. In small molecules, electrons and bonds are arranged as far apart as possible.

2. Molecular Geometry This allows for atoms to have 3-D shapes different from their shapes in 2-D (paper).

3. Molecular Geometry Linear – the bonds form a straight line. Example CO 2 Bond Angle 180⁰ [http://cwx.prenhall.com/bookbind/pubbooks/hillchem3/medialib/media_portfolio/text_images/CH10/FG10_02-02d.JPG]

4. [http://wps.prenhall.com/wps/media/objects/602/616516/Media_Assets/Chapter07/Text_Images/FG07_05-01UN.JPG]

5. Molecular Geometry Trigonal Planar– The central atom has only 3 bonds. Example: CH 2 O (Formaldehyde) Bond angle 120⁰ [http://wps.prenhall.com/wps/media/objects/476/488316/Instructo r_Resources/Chapter_10/FG10_00-66c.JPG]

6. [http://wps.prenhall.com/wps/media/objects/602/616516/Media_Assets/Chapter07/Text_Images/FG07_05-01UN.JPG]

7. Molecular Geometry Tetrahedral –The central atom has only 4 bonds Example: CH 4 (methane) Bond Angle 109.5⁰ [http://wps.prenhall.com/wps/media/object s/476/488316/Instructor_Resources/Chapt er_10/FG10_00-69d.JPG]

8. [http://wps.prenhall.com/wps/media/objects/602/616516/Media_Assets/Chapter07/Text_Images/FG07_05-01UN.JPG]

9. Molecular Geometry Trigonal Pyramidal – Central atom has 3 bonds and one lone pair of electrons that “pushes” the bonds away. Example: NH 3 (ammonia)

10. [http://wps.prenhall.com/wps/media/objects/602/616516/Media_Assets/Chapter07/Text_Images/FG07_05-01UN.JPG]

11. Molecular Geometry Bent – Here there are two bonds and two pairs of electrons on the central atom. Example: H 2 O (water) [http://www.elmhurst.edu/~chm/vchembook/images/206water.gif]

12. [http://wps.prenhall.com/wps/media/objects/602/616516/Media_Assets/Chapter07/Text_Images/FG07_05-01UN.JPG]

14. Polarity When 2 atoms in a bond have different electronegativity values, electrons can be “pulled” more toward one side of the bond. A bond where this occurs is called a dipole.

15. [http://www.cybered.net/library/Teaching_Resources/Chemistry/Bonding_II/Image_Gallery/Bonding2--PolarBond.jpg]

16. [http://cwx.prenhall.com/bookbind/pubbooks/hillchem3/medialib/media_portfolio/text_images/CH09/FG09_11.JPG]

17. Polarity Showing Polarity “Minus” sign above the high electronegative atom. “Plus” sign over the other atom. Draw arrow from plus to minus. [http://cwx.prenhall.com/bookbind/pubbooks/hillchem3/medialib/media_portfolio/text_images/CH09/FG09_11-02.JPG]

18. Compound Polarity Draw a correct 2-D compound with arrows along each bond. Example: CH 4 CH H H H

19. Compound Polarity Then, check to see if any of the arrows cancel out. To do this think “tug of war” CH H H H

20. Compound Polarity If all arrows cancel out, the molecule is non-polar or covalent. If the arrows do not cancel out, the molecule is polar or polar-covalent.

21. Compound Polarity Remember: 3D shape determines 2D drawing. Example: H 2 O HHO H H O