1. Chemical Bonding and Molecular Geometry

2. Valence-Shell Electron-Pair Repulsion
(VSEPR) Theory
Electron pairs repel each other, both bond pairs and unshared (lone pairs)
- Electron pairs assume orientations that minimize repulsions.

3. Applying VSEPR Theory
Draw a Lewis structure
Determine the number of electron groups around the central atom and identify them as being either bond pairs or lone pairs.
Establish the electron group geometry around the central atom-linear,trigonal-planar,tetrahedral
Determine the molecular geometry from the positions around the central atom occupied by the other atomic nuclei.

4. Valence shell electron pair repulsion (VSEPR) model:
Predict the geometry of the molecule from the repulsions between the electron (bonding and nonbonding) pairs.
# of atoms
bonded to central atom
# lone
pairs on central atom
Arrangement of electron pairs
Molecular
Geometry 2
linear
linear B
10.1

5. 0 lone pairs on central atom 2 atoms bonded to central atomCl Be
0 lone pairs on central atom
2 atoms bonded to central atom
10.1

6. Arrangement of electron pairs
VSEPR
# of atoms
bonded to central atom
# lone
pairs on central atom
Arrangement of electron pairs
Molecular
Geometry 2
linear
linear
trigonal planar
trigonal planar 3
10.1

7. 10.1

8. Arrangement of electron pairs
VSEPR
# of atoms
bonded to central atom
# lone
pairs on central atom
Arrangement of electron pairs
Molecular
Geometry
trigonal planar
trigonal planar 3
trigonal planar 2 1
bent
10.1

9. Arrangement of electron pairs
VSEPR
# of atoms
bonded to central atom
# lone
pairs on central atom
Arrangement of electron pairs
Molecular
Geometry 2
linear
linear 3
trigonal planar 4
tetrahedral
tetrahedral
10.1

10. 10.1

11. Arrangement of electron pairs
VSEPR
# of atoms
bonded to central atom
# lone
pairs on central atom
Arrangement of electron pairs
Molecular
Geometry 4
tetrahedral
tetrahedral
trigonal pyramidal 3 1
tetrahedral
10.1

12. 10.1

13. Number of Places Where Electrons are Found
Generic Formula
     
Number of Places Where Electrons  are Found
     
Molecula r  Shape
    
Hybridiz ation MX 1
linear
---
MX2 2 sp
MX3 3
trigonal planar
sp2
MX2E
bent (angular, v-shaped)
MX4 4
tetrahedral
sp3
MX3E
trigonal pyramidal
MX2E2
MX5 5
trigonal bipyramidal
sp3d
MX4E
seesaw (distorted tetrahedral)
MX3E2
T-shaped
MX2E3
MX6 6
octahedral
sp3d2
MX5E
square pyramidal
square planar
Hybrid Atomic Orbitals ( Linus Pauling)
Proposed that the outermost (valence) orbitals of an atom could be combined to form hybrid atomic orbitals.
Sigma bond (
The end-to-end overlapping of an s orbital with a p orbital to form a sp hybrid orbital.
Pi bond (
) - The side-to-side overlapping of two p orbitals.
Single bonds are made up of one sigma bond.
Double bonds are made up of one sigma bond and one pi bond.
Triple bonds are made up of one sigma bond and two pi bonds.
Hybridization - A mixture of two or more atomic orbitals.