Dictionary
se•le•ni•um
Pronunciation: (si-lē'nē-um), [key]—
n. Chem.
a nonmetallic element chemically resembling sulfur and tellurium, occurring in several allotropic forms, as crystalline and amorphous, and having an electrical resistance that varies under the influence of light.
Symbol: Se;
at. wt.: 78.96;
at. no.: 34;
sp. gr.: (gray) 4.80 at 25°C, (red) 4.50 at 25°C.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.