1. Topic: Atomic Structure Aim: How are electron PELs further divided
Topic: Atomic Structure Aim: How are electron PELs further divided? Do Now: Construct a Lewis Dot diagram for Si. HW:

2. Remember when… …we talked about PELs? What can you tell me about them?
…you learned electron configurations?
Let’s modify this model…

3. PELs can be divided
PEL # is only PART of the e- configuration of an element
PELs divided into sublevels
Sublevels are named with letters (s, p, d, or f)
The # of sublevels a PEL can have is equal to the # of the PEL
So… PEL 1 has 1 sublevel, PEL 2 has 2 sublevels, etc.
PELs higher than 4 would contain more than 4 sublevels – haven’t been named yet.

4. Sublevels within PELs PEL 1, 1 sublevel, s PEL 2, 2 sublevels, s and p
PEL 3, 3 sublevels, s, p, and d
PEL 4, 4 sublevels, s, p, d, and f

5. d is double dumbbell and/or donut
Shapes of Sublevels
s is spherical
p is pair of lobes along x, y, or z axis y
d is double dumbbell and/or donut

6. Orbital & Electron Capacity for Sublevels
Sublevels & Orbitals
Sublevels are divided into orbitals (increasing odd numbers, so s has 1, p has 3, d has 5, f has 7)
Each orbital can contain 2 electrons
Orbital & Electron Capacity for Sublevels
Sublevel
# of Orbitals
Max # of e- s 1 2 p 3 6 d 5 10 f 7 14

7. Orbitals & Electron Capacity
PEL
Sublevel type
# of orbitals per type
# of orbitals per PEL
Max # of electrons 1 s 2 4 8 p 3 9 18 d 5 16 32 f 7 } } }

8. Electron Configurations
Show how the electrons fill the orbitals in the PEL sublevels
3 rules…
1. Aufbau principle – e- enter orbitals w/the lowest energy first (so start w/the 1s)
2. Pauli exclusion principle – max of 2 e- per orbital, each w/opposite spins ↑ or ↓
3. Hund’s rule – when e- occupy orbitals of equal energy, they don’t pair up until they have to

9. Hydrogen Atomic #1, 1 electron Goes in 1s Electron configuration 1s1
There is 1 electron in the 1st PEL, s sublevel
1 s 1 ↑  arrow indicates spin

10. Helium Atomic #2, 2 electrons
Goes in 1s (it can hold 2 electrons, remember)
Electron configuration 1s2
There are 2 electrons in the 1st PEL, s sublevel
1 s 2 ↑↓  arrows indicate spin

11. Lithium Atomic #3, 3 electrons Goes in 1s, then 2s
Electron configuration 1s2 2s1
There are 2 electrons in the 1st PEL, s sublevel, 1 electron in the 2nd PEL, s sublevel
Total of superscripts must equal total # of electrons
1 s 2 ↑↓ 2 s 1 ↑ .

12. Beryllium Atomic #4, 4 electrons Goes in 1s, then 2s
Electron configuration 1s2 2s2
There are 2 electrons in the 1st PEL, s sublevel, 2 electrons in the 2nd PEL, s sublevel
1 s 2 ↑↓ 2 s 2 ↑↓

13. Boron Atomic #5, 5 electrons Goes in 1s, then 2s, then 2p
Electron configuration 1s2 2s2 2p1
There are 2 electrons in the 1st PEL, s sublevel, 2 electrons in the 2nd PEL, s sublevel, 1 electron in the 2nd PEL, p sublevel
1 s 2 ↑↓ 2 s 2 ↑↓ 2 p 1 ↑

14. Carbon 1 s 2 ↑↓ 2 s 2 ↑↓ 2 p 2 ↑ . ↑ . . Atomic #6, 6 electrons
Goes in 1s, then 2s, then 2p
Electron configuration 1s2 2s2 2p2
There are 2 electrons in the 1st PEL, s sublevel, 2 electrons in the 2nd PEL, s sublevel, 2 electrons in the 2nd PEL, p sublevel
BUT – the two 2p electrons go into 2 different orbitals! They DON’T PAIR UP unless they have to!
1 s 2 ↑↓ 2 s 2 ↑↓ 2 p 2 ↑ . ↑

15. Nitrogen What would this look like? Electron configuration 1s2 2s2 2p3

16. Oxygen What would this look like? Electron configuration 1s2 2s2 2p4

17. Rvw - Orbitals & Electron Capacity
PEL
Sublevel type
# of orbitals per type
# of orbitals per PEL
Max # of electrons 1 s 2 4 8 p 3 9 18 d 5 16 32 f 7 } } }

18. Orbital Notation: Elements 1-10
Pauli exclusion principle – max of 2 e- per orbital, each w/opposite spins ↑ or ↓
Hund’s rule – when e- occupy orbitals of equal energy, they don’t pair up until they have to

19. Elements 11-18…

20. Continuing…
Elements continue to fill PEL sublevels & orbitals in this fashion…
…until…
POTASSIUM. That jerk.
K’s electron configuration on Periodic Table
Why isn’t it 2-8-9? The 3rd PEL can hold more than 8 electrons (can hold up to 18)

21. Reason Aufbau principle – e- enter orbitals w/the lowest energy first
Sometimes, low energy portions of higher PELs overlap into high energy portions of lower PELs
Huh?
I show you.

22. Potassium
e- config: _______________________ basic e- config: _____________

23. Calcium
e- config: _______________________ basic e- config: _____________

24. Scandium
e- config: _______________________ basic e- config: _____________

25. Titanium
e- config: _______________________ basic e- config: _____________

26. HOW DO YOU KNOW WHICH SUBLEVELS GET FILLED FIRST?
Use the Periodic Table!

29. http://www. wwnorton. com/college/chemistry/gilbert/overview/ch3
“electron configuration tutorial”