The first 20 elements of the periodic table and their symbols are:
- 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)
It’s worth noting that the elements in the periodic table are arranged according to their atomic number, not atomic weight.