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Crystal structure of holmium, hexagonal close-packed. Crystal structure of holmium, hexagonal close-packed.

Holmium

Atomic Number: 67 Atomic Radius: 216 pm (Van der Waals)
Atomic Symbol: Ho Melting Point: 1474 °C
Atomic Weight: 164.9 Boiling Point: 2700 °C
Electron Configuration: [Xe]6s24f11 Oxidation States: 3

History

From the Latin word Holmia meaning Stockholm. The special absorption bands of holmium were noticed in 1878 by the Swiss chemists Delafontaine and Soret, who announced the existence of an "Element X." Cleve, of Sweden, later independently discovered the element while working on erbia earth. The element is named after Cleve's native city. Holmia, the yellow oxide, was prepared by Homberg in 1911. Holmium occurs in gadolinite, monazite, and in other rare-earth minerals. It is commercially obtained from monazite, occurring in that mineral to the extent of about 0.05%. It has been isolated by the reduction of its anhydrous chloride or fluoride with calcium metal.

Properties

Pure holmium has a metallic to bright silver luster. It is relatively soft and malleable and is stable in dry air at room temperature but rapidly oxidizes in moist air and at elevated temperatures. The metal has unusual magnetic properties. Few uses have yet been found for the element. The element, as with other rare earths, seems to have a low acute toxic rating.

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