Aufbau Principle

Principle

Electrons are added to the lowest energy orbital available

Figure

n=2 n=6 n=10 n=14
1s
2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f
6s 6p 6d 6f
7s 7p 7d 7f
n Fill sequence Electrons
n=1 2
n=2 8
n=3 18
n=4 32

Order of filling

Probably a good idea to memorize

Energy