1. Quantum Mechanical View of Atoms

2. The electron can be thought of as spread out in space as a “cloud”.

4. Quantum Mechanics of the Hydrogen Atom

6. n – principal quantum number, positive integer;
l – orbital quantum number, is related to the magnitude of the angular momentum of the electron; at given n can take integer values from 0 to (n-1);
ml – magnetic quantum number, is related to the direction of the electron’s angular momentum, and it can take an integer values from –l to +l.

7. Zeeman Effect

9. Spin Quantum Number, ms

10. Conceptual Example: Possible States for n=3
How many different states are possible for an electron whose principal quantum number is n=3?

11. Selection Rule
Another prediction of quantum mechanics is that when a photon is emitted or absorbed, transitions can occur only between states with values of l that differ by one unit.

12. The Exclusion Principle

13. No two electrons in an atom can occupy the same quantum state.

14. Complex Atoms and Periodic Table of Elements

16. Conceptual Example
Which of the following electron configurations are possible, and which forbidden ?