1. Electron Configuration
Ms. Hoang ACP Chemistry

2. Review 1. Electrons travel in orbits or orbitals? _______________
2. How many principal energy levels are there theoretically? _____________
3. Fill in the table

4. Pauli Exclusion Principle
Spin: up and down-spin
An atomic orbital can hold a maximum of two electrons and those two electrons must have opposite spins
Example: Fill in the table

5. Aufbau Principle + Hund’s Rule
Aufbau: Orbitals of lowest energy are filled first
Hund’s Rule: when there are multiple orbitals of the same energy, fill the electrons in each of them first before doubling up (“no empty bus seat” rule)

6. Spot the mistake! 1s 2s 3s 2p 3p +

7. Spot the mistake! 1s 2s 3s 2p 3p +

8. Spot the mistake! 1s 2s 3s 2p 3p +

9. s p d (n-1) f (n-2) 1 2 3 4 5 6 7 1s 2s 3s 4s 5s 6s 7s 3d 4d 5d 6d 2p

10. Electron Configuration
1s1
group #
# valence e-
possibilities are:
s: 1 or 2
p: 1-6
d: 1-10
f: 1-14
Total e- should equal
Atomic #
row #
shell #
possibilities are 1-7
7 rows
subshell
possibilities are
s, p, d, or f
4 subshells

11. Practice Lithium: find the element on the periodic table atomic # = 3
what is the period number?
how many shells?
what is the group number?
how many valence electrons?
what subshell(s) does Li have?
what is the electron configuration?
atomic # = 3 2 2 1 1 s
1s2 2s1

12. Practice: Your Turn Boron: find the element on the periodic table
what is the row #?
how many shells?
what is the group #?
how many valence electrons?
what subshell(s) does B have?
what is the electron configuration?

13. Electron Configuration v. Orbital DiagramH
= 1s1 1s He
= 1s2 Li
= 1s2 2s1 2s Be
= 1s2 2s2 C
= 1s2 2s2 2p2
2px
2py
2pz S
= 1s2 2s2 2p4 3s
3px
3py
3pz

14. Atomic Sizes in Periodic Table

15. Ionization Energy in Periodic Table