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Related to promethium: Prometrium
n. Symbol Pm
A radioactive element of the lanthanide series that is prepared by fission of uranium or by neutron bombardment of neodymium and has over 30 isotopes, the most stable of which have half-lives of 2.62 years (Pm-147), 5.53 years (Pm-146), and 17.7 years (Pm-145). Promethium-147, the most easily obtained isotope, is used as a source of beta rays. Atomic number 61; melting point 1,042°C; boiling point 3000°C; specific gravity 7.264 (25°C); valence 3. See Periodic Table.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
(Elements & Compounds) a radioactive element of the lanthanide series artificially produced by the fission of uranium. Symbol: Pm; atomic no: 61; half-life of most stable isotope, 145Pm: 17.7 years; valency: 3; melting pt: 1042°C; boiling pt: 2460°C (approx.)
[C20: New Latin from Prometheus]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
pro•me•thi•um(prəˈmi θi əm)
a rare-earth, metallic, trivalent element. Symbol: Pm; at. no.: 61.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
Symbol Pm A radioactive metallic element of the lanthanide series. Promethium does not occur in nature, but it can be found as a product of the fission of uranium. It has 17 isotopes, one of which can be used to make miniature batteries that work at extreme temperatures for up to five years. Atomic number 61. See Periodic Table.
The American Heritage® Student Science Dictionary, Second Edition. Copyright © 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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|Noun||1.||promethium - a soft silvery metallic element of the rare earth group having no stable isotope; was discovered in radioactive form as a fission product of uranium|
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.
n (Chem) → Promethium nt
Collins German Dictionary – Complete and Unabridged 7th Edition 2005. © William Collins Sons & Co. Ltd. 1980 © HarperCollins Publishers 1991, 1997, 1999, 2004, 2005, 2007