Curated category
Chalcogens
- OxygenOxygen is the third most abundant chemical element in the universe, trailing only hydrogen and helium. About 0.9% of the Sun's mass consists of oxygen.
- SeleniumIn 1817, Jöns Jacob Berzelius and Johan Gottlieb Gahn stood before a red solid precipitate in the lead chambers of their chemistry plant near Gripsholm…