1. Quantum Model of the Atom

2. Determining the location of the electron within a given atom is difficult because...

3. 1. Electrons have wave-particle duality (de Broglie)-- meaning they have properties of waves (energy) and properties of particles (matter).
Light had been described as a wave (Huygens) and Light had been described as a particle (Newton, Planck)---de Broglie said it was both
Remember: E=mc2
The mass of an electron is so low…it behaves with more wave properties than matter properties.

4. 2. Heisenberg Uncertainty Prinicple
--it is impossible to know both the exact location and the exact momentum (velocity) of an electron at the same time.
Why? It is moving at close to the speed of light (wave property). Once you know where it is…it has moved before you can measure it.

5. A better method for mathematically describing the “area” around the nucleus where you can find a given electron was developed by Schrodinger — his system used 4 Quantum Numbers to describe the properties(spin) and probability of the location of individual electrons within an atom.

6. Quantum Numbers (there are 4)
1st Quantum Number— Principal Quantum Number (n)-- refers to the energy level of an electron; whole numbers 1,2,3, etc.; electrons always seek the lowest energy level possible (Bohr’s concept)

7. Sub-Level
2nd Quantum # (l)
shapes s
spherical p 1
dumb-bell d 2 f 3
2nd Quantum Number— (l)--refers to the sub-level of the electron within the primary energy level; ranges from 0 to (n-1)

10. http://chemwiki. ucdavis

11. Sub-Level (n)
# of orbitals
Maximum # of electrons s 1 2 p 3 6 d 5 10 f 7 14
3rd Quantum Number (m)--refers to the orbital an electron is in, within each sub-level; each orbital contains a maximum of 2 electrons.

12. 4th Quantum Number (s) — refers to the spin direction of the electron; clockwise = +½ counter clockwise= -½
Each electron in an orbital (remember 2 max) must have opposite spins!
__Pauli Exclusion Principle____—no 2 electrons within an atom have the same 4 quantum numbers.

13. What does it Mean?.....
Nucleus

14. Putting it to use... 1s 2s 2p 3s 3p 3d Order in which energyf= 1s
2s 2p
3s 3p 3d Order in which energy
4s 4p 4d 4f levels and sub-levels fill
5s 5p 5d 5f with electrons!
6s 6p 6d 6f
7s 7p 7d 7f

15. Determining the electron configuration for an atom...
Sodium = Na = ____ Electrons

16. Try one more… Rubidium = ____ electrons