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holmium(hōl`mēəm) [Lat.,=Stockholm], metallic chemical element; symbol Ho; at. no. 67; at. wt. 164.93032; m.p. about 1,474°C;; b.p. about 2,425°C;; sp. gr. 8.78 at 25°C;; valence +3. Holmium is a soft, malleable, lustrous, silvery metal 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.
..... Click the link for more information. in 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
..... Click the link for more information. . It is prepared by reduction of a holmium halide with calcium metal. Holmium is stable in dry air at room temperature but is rapidly oxidized in moist air or when heated. Holmia, the oxide, is found in nature, with 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.
..... Click the link for more information. , in the minerals gadolinite and monazite. Holmium, its oxide, and its salts have no commercial uses. The metal was discovered spectroscopically in 1878 by the Swiss chemists Soret and Delafontaine and independently in 1879 by the Swedish chemist Per T. Cleve; it is named for Cleve's native city.
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A rare-earth element belonging to the yttrium subgroup, symbol Ho, atomic number 67, atomic weight 164.9304, melting point 1400-1525°C.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
a malleable silver-white metallic element of the lanthanide series. Symbol: Ho; atomic no.: 67; atomic wt.: 164.93032; valency: 3; relative density: 8.795; melting pt.: 1474°C; boiling pt.: 2700°C
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