1. Electron Configuration
Where are the electrons???
Each element has a unique e- config.

2. Main energy level (like floors of a building)- # also indicates the number of sublevels
Sublevel (like rooms in a building) – s, p, d, f
Orbitals (like closets) – Can hold 2 electrons
- Sublevels contain orbitals
s sublevel - 1 orbital

3. p sublevel - 3 orbitals

4. d sublevel - 5 orbitals

5. f sublevel - 7 orbitals
(Fill out chart)

6. Total # of electrons in energy level
Energy Level (n)
E sublevel
# of Orbitals
# of e- in each sublevel
Total # of electrons in energy level 1 s 2 p 3 6 8 d 5 10 18 4 f 7 14 32

7. Aufbau Principle
E- occupy the lowest energy level first

8. Pauli Exclusion Principle
Two e- with opposite spin can occupy one orbital.

9. Hund’s Rule
Electrons are spread out in the same sublevel before doubling.

10. Other info
**Valence Electrons – all the e- in the highest main energy level **Inner-shell electrons – all the e- except valence electrons **Complete Octet – 8 valence e-, stable atom (Noble Gases)

12. Orbital Notation
*Orbital (box or line) *Electron (arrow) *Energy level – numbers *Sublevel - letters

13. Orbital Notation ___ ___ ___ ___ ___ ___ ___ ___ ___ 1s 2s 2 p 3s 3p
Electron
Orbital
Energy Level
Sublevel

14. Electron Configuration Notation 1s2 2s2 2p6
Number of e- in orbital
Energy level
Sublevel

15. Examples: O – Si – (valence e-?)

18. Noble Gas Configuration
Noble Gas – Group 18
*Has 8 valence electrons (except He)
*Has a complete octet - unreactive
Use the Noble Gas on the previous row to substitute for part of the electron configuration

20. Lewis Dot Diagrams Dots represent valence electrons
Valence electrons are in “s” and “p” sublevels only, called the “main group” elements.
Group 18 has 8 valence electrons (except for He)
Examples:

21. Excitation of Electrons
Electrons absorb energy
Electrons jump from the ground state to a higher energy level
Unstable electron in excited state falls back down to ground state.
The electron releases a photon.
(Photon is a “packet” of a specific amount of energy that we see as light).

23. Four ways to excite electrons:
Heat
Electricity
Chemiluminescence
UV light