1. VSEPR THEORY

2. VSEPR THEORY
Valence
Shell
Electron
Pair
Repulsion

3. VSPER Theory Definition:
Because electrons repel, molecular shape adjusts so the valence-electron pairs are as
far……………..apart as possible.

4. Molecular Shape The number of atoms bonded to the central atom
The shape of a molecule is determined by 2 factors:
The number of atoms bonded to the central atom
Double and triple bonds don’t change the general shape.
The number of unshared pairs of electrons on the central atom
Unshared pairs of electrons on other atoms in the compound don’t affect the shape.

5. We’ll Study 7 of the Shapes
Linear
Bent
Trigonal Planar
Trigonal Pyramidal
Tetrahedral
Trigonal Bipyramidal
Octahedral

6. F C O Linear 2 atoms bonded to the central atom
0 lone pairs on the central atom
All 2-atom molecules are considered linear. F C O

7. O H Bent 2 atoms bonded to the central atom
1 or 2 lone pairs on the central atom
Notice that the Lewis structure does NOT have to show the bent shape. O H

8. H C O Trigonal Planar 3 atoms bonded to the central atom
0 lone pairs on the central atom
Since there are no lone pairs on the central atom, the compound is flat. C H O

9. N H Trigonal Pyramidal 3 atoms bonded to the central atom
1 lone pair on the central atom
The lone pair on the central atom pushes down on the other 3 atoms causing a pyramidal shape. N H

10. H C Tetrahedral 4 atoms bonded to the central atom
0 lone pairs on central atom C H

11. Trigonal Bipyramidal 5 atoms bonded to the central atom
An expanded octet
Possible for p-group elements from 3rd or later periods
0 lone pairs on central atom

12. Octahedral Called an octahedral due to 8 “faces” of the shape
6 atoms bonded to the central atom
Also an expanded octet
0 lone pairs on central atom
Called an octahedral due to 8 “faces” of the shape

14. Lone Pairs on Center Atom
Summary
Lone Pairs on Center Atom
Atoms Bonded to Center
Shape
Linear
Bent or 2
Trigonal Planar
Trigonal Pyramidal
Tetrahedral
Trigonal Bipyramidal
Octahedral