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