Selenium

Selenium is a chemical element; it has symbol Se and atomic number 34. It has various physical appearances, including a brick-red powder, a vitreous black solid, and a grey metallic-looking form. It seldom occurs in this elemental state or as pure ore compounds in Earth's crust. Selenium (from ) was discovered in 1817 by , who noted the similarity of the new element to the previously discovered tellurium (named for the Earth).

Swedish chemist (1779–1848)

Azerbaijani nuclear physicist (1918–1993)

British engineer (1828–1891)

metal rectifier, invented in 1933, used in power supplies for electronic equipment and in high-current battery-charger applications until the late 1960s

medical condition