1. Original slide prepared for the IGCSE Electron arrangement in Atoms and Ions.

2. Original slide prepared for the electron shells (atom)

3. Original slide prepared for the lithium atom Li 3 atomic number so three electrons X X X 2, 1 XX X

4. Original slide prepared for the carbon atom C 6 atomic number so six electrons X X X 2, 4 XX X X X X

5. Original slide prepared for the sodium atom Na 11 atomic number so eleven electrons X X X X X 2, 8, 1 X XX X X X X X X X X X

6. Original slide prepared for the calcium atom Ca 20 atomic number so twenty electrons X X X X X 2, 8, 2, 2 X X X X X XX X X X X X X X X X XX X X X XX XX

7. Original slide prepared for the electron shells (ion)

8. Original slide prepared for the calcium ion 20 atomic number positive ion X X X X X 2, 8 XX X X X X X X X X Ca 2+ so 20-2 electrons = 18 [ ] 2+ X X X X X X XX XX X X X X XX

9. Original slide prepared for the [ ] magnesium ion 12 atomic number positive ion X X X X X 2, 8 XX X X X X X X X X Mg 2+ so 12-2 electrons = 10 2+

10. Original slide prepared for the chloride ion 17 atomic number negative ion X X X X X 2, 8 XX X X X X X X X X X X X X X X X X X X X X X X XX Cl - - so 17+1 electrons = 18 [ ] -

11. Original slide prepared for the oxide ion 8 atomic number negative ion X X X X X 2, 8 O 2-2- 2- so 8+2 electrons = 10 [ ] 2-2- X X X X X X X X XX