Answer:
Selenium is a non metallic chemical element, member of the group XVI of the periodic table. ... Selenium appearsin a number of allotropic forms: the most popular are a red amorphous powder, a red crystalline material, and a gray crystalline metallike form called metallic selenium.
Discovered by: Jons Berzelius 1817
Atomic number: 34
Atomic mass: 78.96 g.mol -1
Density: 4.79 g.cm-3 at 20°C
