First 25 elements of the periodic table
Hydrogen H
Helium He
Lithium Li
Beryllium Be
Boron B
Carbon C
Nitrogen N
Oxygen O
Fluorine F
Neon Ne
Sodium Na
Magnesium Mg
Aluminum Al
Silicon Si
Phosphorus P
Sulfur S
Chlorine Cl
Argon Ar
Potassium K
Calcium Ca
Scandium Sc
Titanium Ti
Vanadium V
Chromium Cr
Manganese Mn