1. Warm Up: December 10
Distinguish between the Bohr model and the quantum mechanical model of the atom.
2. Carbon-14 is a radioactive isotope that decays by releasing a beta particle. Write the nuclear equation that represents this decay.

2. Molecular Geometry and VSEPR Theory
Whenever the atoms of a molecule bond together, the molecule takes on a particular shape.
Molecular geometry refers to the three-dimensional arrangement of a molecule’s atoms in space.
VSEPR theory is the model used to explain the shapes of molecules.

3. VSEPR – Valence Shell Electron Pair Repulsion Theory.
The main idea of this theory is that electron pairs on the central atom of a molecule will position themselves in such a way as to minimize repulsion.
There are two types of electron pairs: 
bonding pairs (shared)
nonbonding pairs (unshared )

4. Example – CH4
4 electron pairs
4 bonding / 0 nonbonding pairs
molecular geometry = tetrahedral
Example – NH3
4 electrons pairs
3 bonding / 1 nonbonding
molecular geometry = trigonal pyramidal

5. Example – H2O
4 electron pairs
2 bonding / 2 nonbonding
molecular geometry = bent

6. VSEPR and Multiple Covalent Bonds
For the VSEPR model, multiple bonds are counted as one bonding pair when determining the shape of the molecule.
Example – CH2O
3 electron pairs
3 bonding / 0 nonbonding
molecular geometry = trigonal planar

7. Example – NOCl
3 electron pairs
2 bonding / 1 nonbonding
molecular geometry = bent
Example – CO2
2 electron pairs
2 bonding / 0 nonbonding
molecular geometry = linear

8. Bonding Pairs
Nonbonding Pairs
Shape
Example 2
Linear
CO2 3
Trigonal Planar
CH2O 1
Bent
NOCl 4
Tetrahedral
CH4
Trigonal Pyramidal
NH3
H2O

9. Its Your Turn! Predict the shape of the following molecules. PBr3 TeF2
SiO2

10. Outcome Sentences Sentence Starters
After reflecting on today’s lesson, complete three of the sentence starters in your chemistry journal entry for today.
Sentence Starters
I’ve learned…
I was surprised…
I’m beginning to wonder…
I would conclude…
I now realize that… 10