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Helium - Dictionary Definition and Overview |
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Helium : (noun)
1: a very light colorless element that is one of the six inert
gasses; the most difficult gas to liquefy; occurs in
economically extractable amounts in certain natural gases
(as those found in Texas and Kansas) [syn: He, atomic
number 2]
Based on WordNet 2.0
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Helium : \He"li*um\ (h[=e]"l[i^]*[u^]m), n. [NL., fr. Gr. "h`lios
the sun.] (Chem.)
An inert, monoatomic, gaseous element occurring in the
atmosphere of the sun and stars, and in small quantities in
the earth's atmosphere, in several minerals and in certain
mineral waters. Symbol, He; at. wt., 4. Helium was first
detected spectroscopically in the sun by Lockyer in 1868; it
was first prepared by Ramsay in 1895. Helium has a density of
1.98 compared with hydrogen, and is more difficult to liquefy
than the latter. Chemically, it belongs to the argon group
and cannot be made to form compounds. It is a decomposition
product of the radium emanation.
Based on Webster's Revised Unabridged Dictionary
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Helium : \He"li*um\, n. [NL., fr. Gr. ? the sun.] (Chem.)
A gaseous element found in the atmospheres of the sun and
earth and in some rare minerals.
Based on Webster's Revised Unabridged Dictionary
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Helium : Symbol: He
Atomic number: 2
Atomic weight: 4.0026
Colourless, odourless gaseous nonmetallic element. Belongs to group 18 of
the periodic table. Lowest boiling point of all elements and can only be
solidified under pressure. Chemically inert, no known compounds.
Discovered in the solar spectrum in 1868 by Lockyer.
Based on Webster's Revised Unabridged Dictionary (1913)
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