chalcogene

Chalcogens are the chemical elements of group 16 in the periodic table, commonly known as the oxygen family. The group comprises oxygen (O), sulfur (S), selenium (Se), tellurium (Te), polonium (Po), and livermorium (Lv). The name derives from Greek roots meaning "ore-former," reflecting historical associations with minerals and ore deposits.

Chemically, chalcogens range from nonmetals to metalloids and metals. They frequently form compounds with metals called chalcogenides and exhibit oxidation states that include −2 and, for the heavier members, up to +6. Oxygen and sulfur are primarily nonmetallic; selenium and tellurium are metalloids; polonium and livermorium are metals with substantial radioactivity.

Natural occurrence varies widely. Oxygen is one of the most abundant elements in the Earth's crust and a major component of the atmosphere; sulfur occurs in sulfide and sulfate minerals; selenium and tellurium occur as trace byproducts of metal refining; polonium is a rare, highly radioactive element produced in uranium ores; livermorium is synthetic and exists only briefly in laboratory experiments.

Industrial and biological roles also differ. Oxygen is essential for most forms of life and drives combustion. Sulfur is central to fertilizers and many chemicals, while selenium has important electronic and nutritional roles as a trace element. Tellurium is used in alloys and thermoelectrics; polonium has limited niche uses due to radioactivity; livermorium has no practical applications outside research.

Safety note: several chalcogens display significant hazards; polonium and livermorium are highly radioactive, requiring specialized handling. Oxygen and sulfur can be irritants or corrosive in certain compounds, while selenium compounds can be toxic in large amounts.