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Selenium - Dictionary Definition and Overview |
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Selenium : (noun)
1: a toxic nonmetallic element related to sulfur and tellurium;
occurs in several allotropic forms; a stable gray
metallike allotrope conducts electricity better in the
light than in the dark and is used in photocells; occurs
in sulfide ores (as pyrite) [syn: Se, atomic number 34]
Based on WordNet 2.0
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Selenium : \Se*le"ni*um\, n. [NL., from Gr. ??? the moon. So
called because of its chemical analogy to tellurium (from L.
tellus the earth), being, as it were, a companion to it.]
(Chem.)
A nonmetallic element of the sulphur group, and analogous to
sulphur in its compounds. It is found in small quantities
with sulphur and some sulphur ores, and obtained in the free
state as a dark reddish powder or crystalline mass, or as a
dark metallic-looking substance. It exhibits under the action
of light a remarkable variation in electric conductivity, and
is used in certain electric apparatus. Symbol Se. Atomic
weight 78.9.
Based on Webster's Revised Unabridged Dictionary
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Selenium : Symbol: Se
Atomic number: 34
Atomic weight: 78.96
Metalloid element, belongs to group 16 of the periodic table. Multiple
allotropic forms exist. Chemically resembles sulphur. Discovered in 1817
by Jons J. Berzelius.
Based on Elements database 20001107 [ELEM_Dictionary]:
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Selenium : Selenium: An essential trace mineral that functions largely through an association with proteins, called selenoproteins, which act as enzymes and help prevent damage to cells in the body by
oxidants in the environment or those produced by normal metabolism. The recommended dietary allowance (RDA) is currently 55 micrograms of selenium per day for adult men and women, 60 micrograms per day
for women during pregnancy and 70 micrograms per day for women during lactation. Food sources of selenium include seafood; some meats (such as kidney and liver); and some grains and seeds. Too much
selenium (selenosis) may cause reversible balding and brittle nails, give a garlic odor to the breath, and cause intestinal distress, weakness and slowed mental functioning. Deficiency of selenium
causes Keshan disease, a fatal form of cardiomyopathy (heart muscle disease).
Based on Elements database 20001107 [ELEM_Dictionary]:
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