1. Valence-Shell Electron-Pair Repulsion Theory
VSEPR Notes
Valence-Shell Electron-Pair Repulsion Theory

2. VSEPR Theory
VSEPR Theory states that molecules adjust their shapes so that the valence electron pairs are as far apart as possible.

3. Shape Table Bonding directions Lone pairs Shape name picture example 2
linear
bent 3
trigonal planar 1
pyramidal 4
tetrahedral 5
trigonal bipyramidal

5. Linear
Linear—angles are 180°-will be linear if you only have two atoms in the molecule & no lone e- pairs on central atom. Example—HCl or CO2

6. Bent
Bent—2 unshared pairs of e- strongly repels the covalent bonding pairs. All angles are 105°. Example—H2O
Water is NOT linear-- the two lone pairs actually bend the hydrogen atoms away from the oxygen atom!

7. Trigonal planar
Trigonal-Planar—three pairs separate as much as possible, no lone e- pairs on central atom. Example—BF3

8. Pyramidal
Trigonal-Pyramidal—1 unshared pair of e- on central atom strongly repels the covalent bonding pairs, pushing them closer together. All angles are 107 °. Example—NH3

9. Tetrahedral
Tetrahedal—four faced—all angles are 109.5°, no lone e- pairs on central atom. Example—CH4

10. Trigonal bipyramidal
Trigonal Bipyramidal — five pairs separate as much as possible, no lone e- pairs on central atom. Example—PCl5

11. Now you build them!