Iggy's Element Bonanza! Element: Selenium Atomic Symbol: Se Atomic Number: 34 Iggy: Selenium is a nonmetal that is named after the greek word, selene, which means "moon". It had red, black, and gray allotropes. Selenium is also used as pigments for colors. Selenium has five stable isotopes, Se-74, Se-76, Se-77, Se-78, and Se-80. Se-74 and Se-80 have long half lives, so they are considered stable.