Chalcogen
Chalcogen is the name for the elements of Group 16 (VIA) of the periodic table: oxygen, sulfur, selenium, tellurium, polonium, and livermorium. The term comes from Greek chalcos (ore) and genes, reflecting their association with ore deposits and the formation of chalcogenide compounds. They generally have six valence electrons and show oxidation states from -2 to +6, with oxygen the most reactive and the heavier members less so.
Chemically, chalcogens include nonmetals (oxygen, sulfur, selenium) and metalloids or metals (tellurium, polonium, livermorium). They form
Occurrence and uses: Oxygen accounts for about 21% of Earth's atmosphere and is abundant in rocks; sulfur
Biological role: Oxygen is essential for aerobic respiration; sulfur is a component of certain amino acids