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; atomic weight: 78.96; atomic number: 34; specific gravity: (gray) 4.80 at 25°C, (red) 4.50 at 25°C.
Selenium
8 years ago
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