Elements

v. 1. Hydrogen and the noble gases

v. 2. Sodium and potassium

v. 3. Calcium and magnesium

v. 4. Iron, chromium and manganese

v. 5. Copper, silver and gold

v. 6. Zinc, cadmium and mercury

v. 7. Aluminum

v. 8. Carbon

v. 9. Silicon

v. 10. Lead and tin

v. 11. Nitrogen and phosphorus

v. 12. Oxygen

v. 13. Sulfur

v. 14. Chlorine, fluorine, bromine, and iodine

v. 15. Uranium and other radioactive elements

v. 16. Actinium to Fluorine

v. 17. Francium to Polonium

v. 18. Potassium to Zirconium.