1. Electron Configuration

2. Simple model of a potassium atom
Electron Structure
In a neutral atom, electrons = atomic number.
Electrons are arranged into energy levels.
Energy Level (shell) defines how far the electron is away from the nucleus.
n = 1
n = 3
n = 4
More Energy
Nucleus
n = 2
Simple model of a potassium atom

3. Quantum Numbers 4 numbers that define the location and movement of the electrons.

4. Principle Quantum number (n) = Energy Level (shell) defines how far the electron is away from the nucleus.

5. Orbitals Four types: Shells are divided into subshells (orbitals).
Orbital quantum number (l) – defines the shape of the sublevel (orbital).
Four types:
s (sharp)
p (principal)
d (diffuse)
f (fundamental)

6. Magnetic quantum number (m l) – defines the orientation in space of the orbital.
s, p, d, and f orbitals

7. Electron Spin
Spin Quantum number (ms) – designates direction of electron spin.
Each orbital can hold up to 2 electrons.
Why only 2 in each orbital?
Spin up
Spin down

8. Electron Structure Orbitals s / 1 orbital / 2 e- p / 3 orbitals / 6 e-
d / 5 orbitals / 10 e-
f / 7 orbitals / 14 e-

9. Electron Orbitals Aufbau Principle: lowest energy level fills first
Hund’s Rule: electrons fill each orbital before pairing up
“Creepy Bus Guy Rule”
Pauli Exclusion Principle: no two e- will have the same quantum numbers (one spins up, one spins down)
Orbital diagrams

10. Electron Configurations3p 3d 4d 5d 6d 2p 4p 5p 6p 7p 4f 5f
1st row
2nd row
3rd row
4th row
5th row
6th row
7th row
Row number – 1
Row number – 2

11. Lewis Dot Diagrams
Electron Dot Diagram – shows the valence electrons of an atom as dots.
Distribute dots around atomic symbol to represent valence electrons.
Should never have more than 8 dots (octed).
Helium will only have 2 dots (duet).

12. Noble Gas Configuration
Find your element.
Find the noble gas (Group 8A) before your element.
Write the noble gas in brackets.
Add electrons to the noble gas until you reach your element.