Chalcogen
A chalcogen is an element in group 16 of the periodic table. The group includes oxygen, sulfur, selenium, tellurium, polonium, and livermorium.
Periodic table: A tabular arrangement of chemical elements ordered by atomic number and organized by recurring chemical properties. Chalcogens occupy its sixteenth column, whose members share recurring valence-electron patterns.
Chalcogenide: A binary compound containing a chalcogen and a more electropositive element, or an anion derived from a chalcogen. These compounds display how group 16 elements bond with metals and other electropositive partners.
Silicon dioxide: A compound of silicon and oxygen that occurs as quartz and forms the principal component of many glasses. Silica shows oxygen’s central role in minerals, glassmaking, and electronic materials.
Pnictogen: An element in group 15 of the periodic table, including nitrogen, phosphorus, arsenic, antimony, and bismuth. Pnictogens lie immediately left of chalcogens and have five rather than six valence electrons.
Group (periodic table): A vertical column in the periodic table whose elements share related electron configurations and chemical properties. Group membership is the defining feature that makes oxygen through livermorium chalcogens.
Allotropy: The ability of an element to exist in different structural forms in the same physical state. Sulfur, oxygen, and other chalcogens form distinct allotropes with different structures and properties.
Sulfuric acid: A strong mineral acid with formula H₂SO₄, produced on a large scale for industrial use. Its manufacture consumes sulfur and supports fertilizers, refining, and chemical production.
Halogen: An element in group 17 of the periodic table, including fluorine, chlorine, bromine, iodine, and astatine. Halogens neighbor chalcogens and typically need one electron to complete their outer shell.
Valence electron: An electron in an atom’s outer shell that participates in chemical bonding and reactions. Chalcogens generally have six valence electrons, shaping their bonding and oxidation states.
Dioxygen: The diatomic molecular form of oxygen, O₂, that makes up about one-fifth of Earth’s atmosphere. Oxygen’s stable diatomic form contrasts with the structures adopted by heavier chalcogens.