rare earth metal

rare earth metal
Any of a large class of chemical elements including scandium (atomic number 21), yttrium (39), and the 15 elements from 57 (lanthanum) to 71 (see lanthanides).

The rare earths themselves are pure or mixed oxides of these metals, originally thought to be quite scarce; however, cerium, the most plentiful, is three times as abundant as lead in the Earth's crust. The metals never occur free, and the pure oxides never occur in minerals. These metals are similar chemically because their atomic structures are generally similar; all form compounds in which they have valence 3, including stable oxides, carbides, and borides.

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Universalium. 2010.

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  • rare-earth metal — noun see rare earth 2 * * * rare earth element or rare earth metal, any one of a series of metallic elements that have similar properties, ranging from lanthanum (atomic number 57) through lutetium (atomic number 71); lanthanide. Some series do… …   Useful english dictionary

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  • rare earth metal — noun see rare earth element …   New Collegiate Dictionary

  • rare earth — UK US noun [C or U] (also rare earth element, rare earth metal) NATURAL RESOURCES ► one of a group of metal chemical elements that are difficult to find in large quantities, and are important for technology and manufacturing: »Rare earths are key …   Financial and business terms

  • rare earth element — n any of a series of metallic elements of which the oxides are classed as rare earths and which include the elements of the lanthanide series and sometimes yttrium and scandium called also rare earth metal …   Medical dictionary

  • rare-earth element — n. any of the series of metallic chemical elements, with consecutive atomic numbers of 57 (lanthanum) through 71 (lutetium) inclusive: see LANTHANIDE: often called rare earth metal …   English World dictionary

  • rare-earth element — /rair errth /, Chem. any of a group of closely related metallic elements, comprising the lanthanides, scandium, and yttrium, that are chemically similar by virtue of having the same number of valence electrons. Also called rare earth metal. [1955 …   Universalium

  • rare earth — noun any element of the lanthanide series (atomic numbers 57 through 71) (Freq. 1) • Syn: ↑rare earth element, ↑lanthanoid, ↑lanthanide, ↑lanthanon • Hypernyms: ↑group, ↑grouping …   Useful english dictionary

  • rare-earth element — noun any element of the lanthanide series (atomic numbers 57 through 71) • Syn: ↑rare earth, ↑lanthanoid, ↑lanthanide, ↑lanthanon • Hypernyms: ↑group, ↑grouping • Hyponyms: ↑ …   Useful english dictionary

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