1. Chemistry 8.3
8.3

2. 8.3
VSEPR Theory
VSEPR Theory: The Valence-Shell Electron- Repulsion Theory states that molecular shapes adjust in order for valence-electron pairs to stay as far apart as possible.

3. 8.3
VSEPR Theory
Nine Possible Molecular Shapes: (You will be tested over the first five!)
Shown here are common molecular shapes.

4. Tetrahedral Angle 8.3 Example: Methane VSEPR Theory
This comparison of water and carbon dioxide illustrates how unshared pairs of electrons can affect the shape of a molecule made of three atoms. a) The water molecule is bent because the two unshared pairs of electrons on oxygen repel the bonding electrons. b) In contrast, the carbon dioxide molecule is linear. The carbon atom has no unshared electron pairs.
Tetrahedral Angle

5. Pyramidal 8.3 Example: Ammonia has one unshared electron Pair.
VSEPR Theory
Example: Ammonia has one unshared electron Pair.
This comparison of water and carbon dioxide illustrates how unshared pairs of electrons can affect the shape of a molecule made of three atoms. a) The water molecule is bent because the two unshared pairs of electrons on oxygen repel the bonding electrons. b) In contrast, the carbon dioxide molecule is linear. The carbon atom has no unshared electron pairs.
Pyramidal

6. VSEPR Theory
Example: Water (H2O) has 2 unshared pairs.
Bent

7. Linear (180̊) Example: Carbon Dioxide – Carbon has no unshared pairs.
VSEPR Theory
Example: Carbon Dioxide – Carbon has no unshared pairs.
Linear (180̊)

8. Trigonal Planar Example: 3 bonding pairs and 0 unshared pairs.
VSEPR Theory
Example: 3 bonding pairs and 0 unshared pairs.
Trigonal Planar

9. 8.3 Section Quiz.
8.3.

10. 8.3 Section Quiz.
1. A molecular orbital belongs to a
specific atom.
molecule as a whole.
specific pair of atoms.
central atom.

11. 8.3 Section Quiz.
2. VSEPR theory enables prediction of 3- dimensional molecular shape because the valence electron pairs
are attracted to each other.
form molecules with only four possible shapes.
stay as far apart as possible.
always form tetrahedral shapes.

12. 8.3 Section Quiz.
3. Orbital hybridization provides information about
both molecular bonding and molecular shape.
both molecular bonding and bond energy.
neither molecular bonding nor molecular shape.
neither molecular bonding nor bond energy.

13. END OF SHOW