What element has the symbol 'Se'?

The story behind the answer

Se is the symbol for Selenium, a nonmetal in group 16 (the chalcogens) with atomic number 34. Don’t confuse it with Silicon (Si), Sodium (Na, from Latin natrium), or Samarium (Sm).

Selenium was named after Selene, the Greek moon goddess, by Jöns Jakob Berzelius in 1817. It’s used in photoconductors and glassmaking and is an essential trace element in antioxidant enzymes like glutathione peroxidase. Memory tip: “SElenium = SElene (moon) = SE.”