| Share
 

samarium

samarium (səmârˈēəm) [key], metallic chemical element; symbol Sm; at. no. 62; at. wt. 150.36; m.p. 1,072°C; b.p. 1,791°C; sp. gr. 7.54 at 20°C; valence +2 or +3. Samarium is a lustrous silver-white metal. It is one of the rare-earth metals of the lanthanide series in Group 3 of the periodic table. It has two crystalline forms (see allotropy). The metal does not oxidize at room temperature but ignites when heated above 150°C. Samarium is found widely distributed in nature; it is obtained commercially from the minerals monazite and bastnasite. Naturally occurring samarium is a mixture of seven isotopes, three of which are radioactive with extremely long half-lives. The metal was not isolated in relatively pure form until recently, although it has long been used in pyrophoric alloys used in cigarette lighter flints. Samarium is used as a catalyst in certain organic reactions. A samarium-cobalt compound, SmCo5, is used to make magnets for use in computer memories. The oxide, samaria, is used in special infrared absorbing glass and cores of carbon arc-lamp electrodes. Since one isotope of samarium is a good neutron absorber, the element has found use in nuclear reactor control rods. Samarium was discovered in 1879 by P. E. Lecoq de Boisbaudran by spectroscopic analysis of the mineral samarskite.

The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.

More on samarium from Infoplease:

See more Encyclopedia articles on: Compounds and Elements


Premium Partner Content
HighBeam Research
Documents Images and Maps Reference
(from Newspapers, Magazines, Journals, Newswires, Transcripts and Books)

Research our extensive archive of more than 80 million articles from 6,500 publications.

Additional search results provided by HighBeam Research, LLC. © Copyright 2005. All rights reserved.

24 X 7

Private Tutor

Click Here for Details
24 x 7 Tutor Availability
Unlimited Online Tutoring
1-on-1 Tutoring