1. VSEPR and Exceptions to the Octet Rule

2. Recall, Remember, Review
Electrons are the particle:
Responsible for most chemical and physical properties
Responsible for all chemical bonds; they are:
Exchanged in ionic bonds
Delocalized in metallic bonds
Shared in covalent bonds

3. V-Valence S-Shell E-Electron P-Pair R-Repulsion VSEPR Theory
VSEPR theory is based on the idea that the geometry of a molecule or polyatomic ion is determined primarily by repulsion among the pairs of electrons associated with a central atom.
V-Valence
S-Shell
E-Electron
P-Pair
R-Repulsion

4. V-Valence S-Shell E-Electron P-Pair R-Repulsion VSEPR Theory
The pairs of electrons may be bonding or nonbonding (also called lone pairs).

5. V-Valence S-Shell E-Electron P-Pair R-Repulsion VSEPR Theory
Only valence electrons of the central atom influence the molecular shape in a meaningful way because their locations provide the points of connection between atoms when electrons are shared in bonds.
V-Valence
S-Shell
E-Electron
P-Pair
R-Repulsion

6. The Valence Shell
The Valence Shell is composed of the “s” and “p” orbitals. The “s” orbital is lower energy than a “p” orbital.

7. The Valence Shell
When the valence shell is full of electrons or when electrons are added to the valence shell through bonding, the “s” and “p” orbitals morph in a single equal energy orbital called a HYBRIDIZED MOLECULAR ORBITAL or Hybrid Orbital.

8. Sometimes the “d” orbital gets involved “sp3d” hybrid “sp3d2” hybrid
Hybrid Orbitals
“sp” hybrid
“sp2” hybrid
“sp3” hybrid
Sometimes the “d” orbital gets involved
“sp3d” hybrid
“sp3d2” hybrid

9. The sp3 hybrid orbital is
by far the most common hybrid orbital. It is the orbital of the Octet Rule--4 equal pairs of electrons. Its shape is the tetrahedron.

10. Exceptions to the Octet Rule
“sp” Hybrid--2 electron pairs
Shape: linear
Example: BeH2
“sp2” Hybrid--3 electron pairs
Shape: trigonal planar
Example: BF3

11. Exceptions to the Octet Rule
“sp3d” Hybrid--5 electron pairs
Shape: trigonal bipyramidal
Example: PCl5
“sp3d2” Hybrid--6 electron pairs
Shape: octahedral
Example: SF6