1. Electron Orbitals

2. Orbitals and shells
Electrons are located in orbitals around the nucleus
Several orbitals make up a shell
Some shells have more orbitals than others
Each orbital can hold 2 electrons
Each of these electrons spins in a different direction
No two electrons can occupy the same shell, orbital, and have the same spin

3. S orbital

4. S orbital

5. P orbital

6. D orbital

7. F orbital

9. Valence Electrons
The electrons in the outermost shell (with the highest principle quantum number) are the valence electrons
Valence electrons are responsible for chemical reactivity
This is because they are the furthest from the nucleus so the nucleus can’t hold them as tight
Elements are most stable with a full outer shell
They seek 0 or 8 valence electrons
Exception is helium, which is stable with 2

10. Ions
An ion has fewer or more electrons than protons, giving it a charge
Positive ions are called cations
Negative ions are called anions

11. Electron Dot Diagrams (Lewis structures)
Write the element symbol
Find out how many valence electrons the element has
Groups 1A-8A on the periodic table have 1-8 valence electrons each
The exception is He, which has two

13. Electron Dot Diagrams (Lewis Structures)
Draw dots around the element symbol for each valence electron
H F Ra
B Sn Xe

15. K₂CO₃ = potassium carbonate
Na₂SO₄ = sodium sulfate
K₂CrO₄ = potassium chromate
Mg(NO₃)₂ = magnesium nitrate
Ca(NO₃)₂ = calcium nitrate
Sr(NO₃)₂ = strontium nitrate
Ba(NO₃)₂ = barium nitrate