1. The Electron
You are here

2. In Orbitals…More like a Cloud
Region where there is 90% probability of finding an electron.
Can’t pinpoint the location of an electron.
Density of dots represents degree of probability.

3. Energy Levels Electrons can only exist at certain energy levels.
Low energy levels called ground state
Higher energy level called excited state

4. Did you know that light/energy given off by something is simply the energy released when an electron falls from its excited state to its ground state?

5. Electron Diagrams (Bohr Model)
Simplified energy levels using Bohr’s idea of circular orbits.
Can replace with: 3p 4n
Lithium
Atomic #: 3
Mass:
# of p: 3
# of e: 3
# of n: 4 e- e- p n
Maximum e-
Level 1 2e-
Level 2 8e-
Level 3 18e-
Level 4 32e- e-

6. Valence Electrons
Electrons in the outermost energy level (the n) of an atom
These are what ultimately determine an atom’s chemical properties

7. Lewis Structures (or Electron Dot Diagrams)
Shows the valence electrons on an atom by drawing dots around the chemical symbol to represent those electrons

8. Lewis Structures (or Electron Dot Diagrams)
The electrons are drawn, going clockwise, one on each side of the symbol before pairing them 1 5 X 2 8 6 4 7 3

9. Elements in the same group have the same number of valence electrons.1 2
3-12
Most have 2 13 14 4 15 5 16 6 17 7 18 8

10. For Example It’s outermost energy level is 2 (Think 2nd row)
So it has 5 valence electrons
(Think 2 e- on it’s s + 3 e- on it’s p)

11. It’s Lewis Structure would be
For Example (cont.)
It’s Lewis Structure would be N

12. Some books and websites have the dots starting from the top and some don’t always go clockwise. The point is that as long as the number of electrons is drawn and each side has one before they are paired then it is ok. ALL of these are technically correct. S S S

13. d s p Orbitals f orbital? Mind = blown!
Orbitals have different shapes. d s p
f orbital? Mind = blown!

14. Blocks of the Periodic Table