1. Electron Sublevels

2. Energy Levels Originally taught simplistic view 7 levels Level 1 = 2 electrons max Level 1 = 2 electrons max Level 2 = 8 electrons max Level 2 = 8 electrons max Level 3 = 18 electrons max Level 3 = 18 electrons max Level 4 = 32 electrons max Level 4 = 32 electrons max Etc. Etc. Reality - Levels are actually broken into sublevels

3. 2 Sublevels P S Can hold 6 electrons max Can hold 2 electrons max Example: Second level is broken into 2 sublevels Second level is broken into 2 sublevels Holds 8 electrons total Holds 8 electrons total S sublevel holds 2 max P sublevel holds 6 max Fills from bottom to top

4. 3 Sublevels P S Can hold 6 electrons max Can hold 2 electrons max DCan hold 10 electrons max Example: Third level is broken into 3 sublevels Third level is broken into 3 sublevels Holds 18 electrons total Holds 18 electrons total S sublevel holds 2 max P sublevel holds 6 max D sublevel holds 10 max Fills from bottom to top

5. Writing Sublevels Write: Level, sublevel, electrons Written as 2s 2 and 2p 6 The exponents represent electrons Can be less than max. in that level. Example: 2s 1 or 2p 2 or 2p 5 Example: 2s 1 or 2p 2 or 2p 5 2 P S Can hold 6 electrons max Can hold 2 electrons max 2p 6 2s 2

6. Simplistic View vs. Sublevels 1s 2 =2 2s 2 2p 6 =8 3s 2 3p 6 3d 10 =18 4s 2 4p 6 4d 10 4f 14 =32 Sublevels added together still add to simplistic view

7. Problem Levels don’t fill in a neat order. They overlap each other and get mixed together. Fill from the bottom to the top 4 3 4S fills before 3D 3s 4f 4d 3d 4s 3p 4p

8. 1 2 5 4 3 3s 4f 4d 3d 4s 3p 4p 5s 2p 2s 1s 5d 5p 6s 6p 6

9. Fill Order The actual order is a mess. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 5d 10 6p 6 7s 2 5f 14 6d 10 7p 6 5g 18 6f 14 7d 10 etc. Can be memorized.

10. 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 4d 10 4f 14 5s 2 5p 6 5d 10 5f 14 5g 18 6s 2 6p 6 … Arranging Sublevels 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 Draw diagonal lines to figure out the fill order.

11. 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 4d 10 4f 14 5s 2 5p 6 5d 10 5f 14 5g 18 Writing Elements 1s 2 2s 2 2p 6 3s 2 Example: Magnesium has 12 electrons

12. 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 5g Writing Elements 1s 2 2s 2 2p 6 3s 1 Example: Sodium has 11 electrons Notice that the 3s sublevel is not full

13. Valence Electrons Writing sublevels is done to figure out the number of valence electrons Valence electrons determine how an atom reacts The number of electrons in the highest level

14. Determining Valence Electrons Example: Magnesium 1s 2 2s 2 2p 6 3s 2 2 valence electrons 3 is the highest level and there are 2 electrons Example: Phosphorus 1s 2 2s 2 2p 6 3s 2 3p 3 5 valence electrons 3 is the highest level and there are 5 electrons total Example: Iron 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 6 2 valence electrons 4 is the highest level and there are 2 electrons

15. End

16. 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 5g 6s 6p … Order Chart Draw diagonal lines to figure out the fill order.

17. 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 4d 10 4f 14 5s 2 5p 6 5d 10 5f 14 5g 18 6s 2 6p 6 … Order Chart Draw diagonal lines to figure out the fill order.