Electron
Configuration
MS. HOANG ACP CHEMISTRY
Review
1. Electrons travel in orbits or orbitals? _______________
2. How many principal energy levels are there theoretically? _____________
3. Fill in the table
Principal Energy
Level
Sublevels (s, p, d, f)
Orbitals
Electrons (↑ or ↓)
#'s Electrons
Total #'s electrons
n=1
n=2
n=3
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
Principal Energy
Level
Sublevels (s, p, d, f)
Orbitals
Electrons (↑ or ↓)
n=1
n=2
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)
Spot the mistake!
3p
3s
2p
2s
1s
+
Spot the mistake!
3p
3s
2p
2s
1s
+
Spot the mistake!
3p
3s
2p
2s
1s
+
s
1
2
3
4
5
6
7
p
1s
2s
f
2p
3s
d (n-1)
4s
3d
4p
5s
4d
5p
6s
5d
6p
7s
6d
7p
6
(n-2)7
3p
4f
5f
1s
Electron Configuration v. Orbital
Diagram
H = 1s1
1s
He = 1s2
1s
Li = 1s2 2s1
1s
2s
1s
2s
1s
2s
2px 2py 2pz
1s
2s
2px 2py 2pz
Be = 1s2 2s2
C = 1s2 2s2 2p2
S = 1s2 2s2 2p4
3s
3px 3py 3pz
Atomic Sizes in Periodic Table
Ionization Energy in Periodic Table