1. Quantum Numbers and Electronic Configuration http://www.aip.org/history/heisenberg/p08.htm

2. Heisenberg’s Uncertainty Principle(1901-1976) The principle states that it is impossible to know the exact position and momentum of an electron.

3. How do I know how the electrons are distributed around Si ?

4. QUANTUM NUMBERS The shape, size, and energy of each orbital is a function of 4 quantum numbers which describe the location of an electron within an atom or ion n ---> energy level l ---> sublevel,shape of orbital ml ---> designates the rotation of the orbital s ---> spin of the electron (clockwise or counterclockwise:

5. 1. Principal quantum number (n) Describes the energy level where the e - can be found.

6. 2. Angular Quantum Number(l) The orbitals, associated with each energy, determine where the electrons are located. This quantum number can take on the values: l=0 (s-orbital) l=1 (p-orbital) l=2 (d-orbital) l=3 (f-orbital)

7. 3.Magnetic Quantum Number ml Magnetic quantum numbers give the 3D orientation of each orbital.

8. 4. Spin quantum number Describes the spin of the electron.

9. Electron Configuration Electron configuration is a shorthand notation for describing the arrangement of the electrons about the nucleus. General format using the quantum numbers: n l e- n l e- n = principle quantum number l = orbital quantum number e- = number of electrons

10. Hydrogen: 1s 1

12. Examples Electronic Configuration: C 1s 2 2s 2 2p 2 2, 4 Si How do we know how many electrons are in each level?

13. Electronic Configuration simulation http://chemmovies.unl.edu/ChemAnime/EC ONFIG/ECONFIG.html

14. Periodic Table and electronic configuration