Hydrogen
1, H, ***
Helium
2, He, ***
Lithium
3, Li, *
Beryllium
4, Be, *
Boron
5, B, *
Carbon
6, Ca, *
Nitrogen
7, N, ***
Oxygen
8, O, ***
Fluorine
9, F, ***
Neon
10, Ne, ***
Sodium
11, Na, *
Magnesium
12, Mg, *
Aluminium
13, Al, *
Silicon
14, Si, *
Phosphorus
15, P, *
Sulphur
16, S, *
Chlorine
17, Cl, ***
Argon
18, Ar, ***
Potassium
19, K, *
Calcium
20, Ca, *