What is the atomic number for the chemical element which is also a radioactve chalcogen?
Chalcogenide glass Chalcogenide glass (hard "ch" as in "chemistry") is a glass containing one or more chalcogens (sulfur, selenium and tellurium, but excluding oxygen). Such glasses are covalently bonded materials and may be classified as covalent network solids. Polonium is also a chalcogen but is not used because of its strong radioactivity. Chalcogenide materials behave rather differently from oxides, in particular their lower band gaps contribute to very dissimilar optical and electrical properties.
Hydrogen selenide Hydrogen selenide is an inorganic compound with the formula HSe. This hydrogen chalcogenide is the simplest and most commonly encountered hydride of selenium. HSe is a colorless, flammable gas under standard conditions. It is the most toxic selenium compound with an exposure limit of 0.05 ppm over an 8-hour period. Even at extremely low concentrations, this compound has a very irritating smell resembling that of decayed horseradish or 'leaking gas', but smells of rotten eggs at higher concentrations.