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Holmium

Author: Robert Husted, Mollie Boorman

Atomic Number 67
Atomic Symbol Ho
CAS ID No. 7440-60-0
Atomic Weight 164.9300 amu
Electron Configuration [Xe] 4f11 6s2
Melting Point 1470.0 C
Boiling Point 2695 C
Density 8.800 g/cm3
History

(L. Holmia: 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.




Last Update: 2011-02-16