europium

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europium

(yo͝orō`pēəm) [from Europe], metallic chemical element; symbol Eu; at. no. 63; at. wt. 151.964; m.p. about 820°C;; b.p. about 1,600°C;; sp. gr. 5.25 at 25°C;; valence +2 or +3. Europium is a ductile silvery-white metal; it is both rare and expensive. It is a member of Group 3 of the periodic tableperiodic table,
chart of the elements arranged according to the periodic law discovered by Dmitri I. Mendeleev and revised by Henry G. J. Moseley. In the periodic table the elements are arranged in columns and rows according to increasing atomic number (see the table entitled
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. Its oxides are found in minerals with the other rare earthsrare earths,
in chemistry, oxides of the rare-earth metals. They were once thought to be elements themselves. They are widely distributed in the earth's crust and are fairly abundant, although they were once thought to be very scarce.
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. Europium has been identified in the sun and some stars by spectroscopy. Its physical properties are like those of the other members of the lanthanide serieslanthanide series,
a series of metallic elements, included in the rare-earth metals, in Group 3 of the periodic table. Members of the series are often called lanthanides, although lanthanum (atomic number 57) is not always considered a member of the series.
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, but many of its chemical properties are more like those of calcium. The most reactive of the rare-earth metalsrare-earth metals,
in chemistry, group of metals including those of the lanthanide series and actinide series and usually yttrium, sometimes scandium and thorium, and rarely zirconium. Promethium, which is not found in nature, is not usually considered a rare-earth metal.
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, it tarnishes quickly in air at room temperature and ignites and burns above 150°C;. It reacts readily with water. Twenty-one isotopes of europium are known, most of them unstable. Since it is a good neutron absorber, europium metal is used in nuclear reactor control rods. Europium oxide, a pinkish powder, is used to activate red phosphors in the manufacture of color television picture tubes. The discovery of europium is credited to Eugène Demarcay, who isolated fairly pure europium oxide in 1901.

europium

[yu̇′rō·pē·əm]
(chemistry)
A member of the rare-earth elements in the cerium subgroup, symbol Eu, atomic number 63, atomic weight 151.96, steel gray and malleable, melting at 1100-1200°C.

europium

a soft ductile reactive silvery-white element of the lanthanide series of metals: used as the red phosphor in colour television and in lasers. Symbol: Eu; atomic no.: 63; atomic wt.: 151.965; valency: 2 or 3; relative density: 5.244; melting pt.: 822?C; boiling pt.: 1527?C