Question

Composition of atoms of first 20 elements with mass number

Answer 1

Hydrogen - H 1.

Helium - He 2.

Lithium - Li 3.

Beryllium - Be 4.

Boron - B 5.

Carbon - C 6.

Nitrogen - N 7.

Oxygen - O 8.

Fluorine - F 9.

Neon - Ne 10.

Sodium - Na 11.

Magnesium - Mg 12.

Aluminum (or Aluminium) - Al 13.

Silicon - Si 14.

Phosphorus - P 15.

Sulfur - S 16.

Chlorine - Cl 17.

Argon - Ar 18.

Potassium - K 19.

Calcium - Ca 20.