After today, you will be able to…

1. After today, you will be able to… • Explain Valence Shell Electron Pair Repulsion Theory (VSEPRT) • Use structural formulas to describe the molecular geometry of atoms • Identify the correct geometric name for the shape of the molecule • Identify bond angles for molecules

2. Day 4 - Notes Unit 4: Chemical Bonding Molecular Geometry

3. Molecular Geometry • Valence Shell Electron Pair Repulsion Theory (VSEPR):The electron pairs (both shared and unshared) in the outermost energy level try to get as far apart from each other as possible. • This determines the shape of the molecule.

4. Shape: Linear 2 atoms • Example: H2 3 atoms • Example: CO2 ~180˚ O H C H O Central atom must have NO unshared pairs

5. Shape: Bent 3 atoms • Example: H2O O Central atom can have one or two unshared pairs of electrons H ~104.5˚ H

6. Shape: Trigional Planar 4 atoms • Example: CH2O O ~120˚ C Central atom has NO unshared pairs H H

7. Shape: Pyramid 4 atoms • Example: NH3 Central atom has one unshared pair H H N ~107.5˚ H

8. Shape: Tetrahedral 5 atoms • Example: CH4 Central atom has NO unshared pairs H ~109.5˚ H H C H

9. Shape: Trigional Bipyramidal • 6 atoms • Example: PF5 Central atom has NO unshared pairs F ~90˚ F F F ~120˚ P For elements in period 3 and higher, when bonded to Cl or F, will have an expanded octet. F

10. Summary of Shapes Linear Bent Trigional planar Pyramid Tetrahedral Trigional bipyramidal