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| to remove impurities from a gas by chemical means, as sulfur dioxide from smokestack gas or carbon dioxide from exhaled air in life-support packs |
| a purplish-red, water-soluble powder, C20H11N2O10Na3, an azo dye used chiefly to color pharmaceuticals, food, and garments |
selenium se·le·ni·um (sĭ-lē'nē-əm)
n.
Symbol Se
A nonmetallic element, with red, black, and gray allotropic forms, resembling sulfur and obtained primarily as a byproduct of electrolytic copper refining. Atomic number 34; atomic weight 78.96; melting point (of gray selenium) 221°C; boiling point (gray) 684.9°C; specific gravity (gray) 4.79; (black) 4.28; valence 2, 4, or 6.
| selenium (sĭ-lē'nē-əm) Pronunciation Key
Symbol Se A nonmetallic element that occurs in a gray crystalline form, as a red powder, or as a black glassy material. It is highly photosensitive and can be used to convert light into electricity. Its ability to conduct electricity also increases with higher exposure to light. For these reasons selenium is used in photocopying technology, photography, and solar cells. Atomic number 34; atomic weight 78.96; melting point 217°C; boiling point 684.9°C; specific gravity (gray) 4.79; (red) 4.5; (black) 4.28; valence 2, 4, or 6. See Periodic Table. |