1. Quantum Mechanical Model
AWESOME
Quantum Mechanical Model
February 28, 2007
Chem 102B

2. Probability of electron in 3-D space around the nucleus
1s Orbital ()

3. More “s” orbitals
The higher the energy level, the larger the size, and the more nodes that are present
Note the Nodes

4. Nodes
Region of zero probablity

5. “P” Orbitals
Dumbell shapes
Sets of 3

6. The 3p orbital has 3 nodes

7. “D” Orbitals

8. “F” Orbitals

9. Quantum Numbers n - principal Size and Energy l - angular Shape
integer values
l - angular Shape
integral values from 0 to n-1
ml - magnetic Orientation
integral values from -l to l including 0
ms - spin Spin
+1/2 or -1/2

10. Pauli Exclusion Principle
Two electrons in the same orbital have opposing spins
In a given atom: No two electrons can have same QN’s!

11. Aufbau Principle “Building up” Add electrons one at a time
Energy tells us what order to fill the electrons in the orbitals - Hund’s Rule
Lowest energy equals max number of “unpaired electrons”

12. Periodic Table

13. Ionization Energies
Energy required to completely remove an electron from an atom.

14. Electron Affinity
The energy change associated with the addition of an electron to a gaseous atom
X(g) + e-  X-(g)
Atoms that tend to form negative ions release more energy when an electron is added

15. Atomic radius
Half the distance between the nuclei in a molecule consisting of identical atoms
Not exact measure!

16. Radii trends
Down the group the atoms get larger, more electrons, bigger size.
Across the period the atoms get smaller, why?

17. Summary of Trends
Too erratic to predict IE EA R