- The energy levels are called Principle Energy Levels
- The principal energy levels contain sub-levels. Each principal energy contains a different number of sub-levels.
Principal Energy Level |
Number of Sub-levels |
1 |
1 (S) |
2 |
2 (S,P) |
3 |
3 (S,P,D) |
4 |
4 (S,P,D,F) |
Sub-level |
Max number of Electrons |
S |
2 |
P |
6 |
D |
10 |
F |
14 |
Principal Energy Level, n |
Sub-level |
Max Number of Electrons |
1 |
1s |
2 |
2 |
2s,2p |
8 |
3 |
3s,3p,3f |
18 |
4 |
4s,4p,4d,4f |
31 |
e.g.
- a) Sodium = S block
- b) Iron = D block
- c) Sulphur = P block
- d) Chlorine = P block
- c) Radium = S block
- e) Neon = P block
Electron Configurations
Element |
Electron Configuration |
Hydrogen |
1s1 |
Helium |
1s2 |
Lithium |
1s1, 2s1 |
Beryllium |
1s1, 2ss |
Boron |
1s1, 2ss,2p |
Carbon |
1s1, 2ss,2p2 |
Neon |
1s1, 2ss,2p3 |
Oxygen |
1s1, 2ss,2p4 |
Fluorine |
1s1, 2ss,2p5 |
Neon |
1s1, 2ss,2p6 |
Sodium |
1s1, 2ss,2p6, 3s |