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1. Electron
Pair
Repulsion
Theory
Planar
triangular
Tetrahedral
Trigonal
pyramidal
Bent

2. VSEPR theory assumes that the shape of a
molecule is determined by the repulsion of
electron pairs.
Molecular Shape

3. VSEPR Theory
 Based on Electron Dot (Lewis structures)
 Theory predicts shapes of compounds
 abbreviated VSEPR
 VSEPR (pronounced “vesper”) stands for Valence Shell Electron Pair
Repulsion
 VSEPR predicts shapes based on electron pairs repelling (in bonds or by
themselves)
 Electrons around central nucleus repel each other. So,
structures have atoms maximally spread out

4. VSEPR overview
 Each shape has a name
(you will have to know these)
 Names of Shapes:
tetrahedral
trigonal pyramidal
Bent
Linear
trigonal planar

5. Triangular Planar
Tetrahedral
Trigonal pyramidal
Linear
Bent or V
Models

6. C
H
H
H
H methane, CH4
Bonds are all evenly spaced electrons
109.5°
C
H
H
H
H
Tetrahedral

7. N
H H
H
C
H
H
H
H
Less repulsion between the bonding pairs of electrons
.. ammonia
NH3
..
..
..
Trigonal
Pyramidal

8. C
H
H
H
H N
H H
H
O
H H
.. ..
..
109.5° (109.5°) 109.5° (107°) 109.5° (104.5°)
water, H2O

9. C
H
H
H
H N
H H
H
O
H H
.. ..
..

10. H
C
H H
H
N
H H
H
O
H H
Bent or V
2 unshared pairs of e’s
at top of O repel bonds
and force them to bend

11. Molecule Lewis Structure Number of
electron pairs
CH4
NH3
SHAPE
Tetrahedral
Trigonal
Pyramidal
4
4
(3 shared
1 lone pair)

12. Molecule Lewis Structure Number of
electron pairs
H2O
CO2
SHAPE
Bent or V
4
(2 shared
2 lone pairs)
2
Linear

13. Molecule Lewis Structure Number of
electron pairs
BeCl2
BF3
SHAPE
2
3
Linear
Trigonal
Planar