Prometium: Béda antara owahan

Promethium can be formed in nature as a product of [[spontaneous fission]] of [[uranium-238]] and [[alpha decay]] of [[europium]]-151. Only trace amounts can be found in naturally occurring ores: a sample of [[pitchblende]] has been found to contain promethium at a concentration of four parts per quintillion (10¹⁸) by mass.<ref>{{cite journal | last = Attrep | first = Moses, Jr. | coauthors = and P. K. Kuroda | year = 1968 | month = May | title = Promethium in pitchblende | journal = Journal of Inorganic and Nuclear Chemistry | volume = 30 | issue = 3 | pages = 699&ndash;703699–703 | doi = 10.1016/0022-1902(68)80427-0 }}</ref> It was calculated that the equilibrium mass of promethium in the [[earth crust]] is about 560 g due to uranium fission and about 12 g due to the recently observed alpha decay of europium-151 <ref>{{cite journal | author = P. Belli, R. Bernabei, F. Cappella, R. Cerulli, C.J. Dai, F.A. Danevich, A. d’Angelo, A. Incicchitti, V.V. Kobychev, S.S. Nagorny, S. Nisi, F. Nozzoli, D. Prosperi, V.I. Tretyak, S.S. Yurchenko | year = 2007 | month = | title = Search for α decay of natural Europium | journal = Nuclear Physics A | volume = 789 | issue = | pages = 15&ndash;2915–29 | doi = 10.1016/j.nuclphysa.2007.03.001 }}</ref>

Promethium has also been identified in the spectrum of the star [[HR 465]] in [[Andromeda (constellation)|Andromeda]], and possibly HD 101065 ([[Przybylski's star]]) and HD 965.<ref>{{cite journal | author = C. R. Cowley, W. P. Bidelman, S. Hubrig, G. Mathys, and D. J. Bord | year = 2004 | title = On the possible presence of promethium in the spectra of HD 101065 (Przybylski's star) and HD 965 | journal = Astronomy & Astrophysics | volume = 419 | pages = 1087&ndash;10931087–1093 | doi = 10.1051/0004-6361:20035726 }}</ref>

* [http://periodic.lanl.gov/elements/61.html Los Alamos National Laboratory &ndash;– Promethium]

* [http://www.webelements.com/webelements/elements/text/Pm/index.html WebElements.com &ndash;– Promethium]

* [http://education.jlab.org/itselemental/ele061.html It's Elemental &ndash;– Promethium]

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