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Promethium Information

Promethium ( / p r ɵ ˈ m iː θ i ə m / pro-mee-thee-əm) is a chemical element with the symbol Pm and atomic number 61. It is notable for being the only exclusively radioactive element besides technetium that is followed by chemical elements with stable isotopes.

Contents

History

Prediction

The existence of promethium was first predicted by Bohuslav Brauner in 1902.[2] During his research on the chemical properties of rare earth elements he found that the difference between neodymium and samarium is larger than between the other lanthanides.[2] This prediction was supported in 1914 by Henry Moseley who, having discovered that atomic number was an experimentally measurable property of elements, found that no known element had atomic number 61.[3] With the knowledge of a gap in the periodic table several groups started to search for the predicted element among other rare earths in the natural environment.[3]

Florentium and Illinium

The first claim of a discovery was published by Italian scientists Luigi Rolla and Lorenzo Fernandes from Florence. After separating a didymium nitrate concentrate from the Brazilian mineral monazite by fractionated crystallisation, they yielded a solution containing mostly samarium. This solution gave x-ray spectra attributed to samarium and element 61. In honor of their city they named element 61 Florentium. The results were published in 1926, but the scientists claimed that the experiments were done in 1924.[4][5][6][7][8][9]

Also in 1926, a group of scientists from the University of Illinois at Urbana-Champaign, Smith Hopkins and Len Yntema published the discovery of element 61. They named it illinium, after the university.[10][11][12]

Both of these reported discoveries are now known to be erroneous because there are no stable or long-lived isotopes of promethium, hence there was none to be found in these sources.

True promethium

Promethium was first produced and characterized at Oak Ridge National Laboratory (ORNL) in 1945 by Jacob A. Marinsky, Lawrence E. Glendenin and Charles D. Coryell by separation and analysis of the fission products of uranium fuel irradiated in the Graphite Reactor; however, being too busy with military-related research during World War II, they did not announce their discovery until 1947.[13] The name promethium is derived from Prometheus, the Titan, in Greek mythology, who stole fire from Mount Olympus and brought it down to mankind. The name was suggested by Grace Mary Coryell, Charles Coryell's wife, who felt that they were stealing fire from the gods.

In 1963, ion-exchange methods were used at ORNL to prepare about ten grams of promethium from nuclear reactor fuel processing wastes.[14][15]

Today, promethium is still recovered from the byproducts of uranium fission; it can also be produced by bombarding 146Nd with neutrons, turning it into 147Nd which decays into 147Pm through beta decay with a half-life of 11 days.

Occurrence

Pitchblende

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.[16] It was calculated that the equilibrium mass of promethium in the earth's crust is about 560g due to uranium fission and about 12g due to the recently observed alpha decay of europium-151.[17]

Promethium has also been identified in the spectrum of the star HR 465 in Andromeda, and possibly HD 101065 (Przybylski's star) and HD 965.[18]

Characteristics

See also: Isotopes of promethium

Promethium is the only lanthanide and one of two elements among the first 82 that has no stable (or even long-lived) isotopes; this is a result of a rarely occurring effect of the liquid drop model and stabilities of neighbor element isotopes. The most stable isotope of the element is promethium-145, which has a half-life of 17.7 years.[19] In other words, if a kilogram of pure promethium-145 could be created at a moment, only about 20 grams would be left after 100 years. Promethium is also the least stable element of the first 84.[19] The primary decay products are neodymium and samarium isotopes (promethium-146 decays to both, the lighter generally to neodymium, and heavier to samarium). Exact promethium isotopes may decay to praseodymium or other promethium isotopes (in case of nuclear isomers).[19]

Promethium is a lanthanide metal whose chemical properties mostly resemble those of other lanthanides. The melting point of the element was claimed to have been calculated to be around 1042 °C (1908 °F, 1315 K), well suiting in the general trend of its increase with atomic numbers in lanthanides. Pure promethium exists in two allotropic forms, and its chemistry is similar to other lanthanides. Promethium salts luminesce in the dark with a pale blue or greenish glow, due to their high radioactivity.

Chemical properties

Promethium metals tarnish slowly in air and burns readily at 150 °C to form promethium oxide:

4 Pm + 3 O2 → 2 Pm2O3

Promethium is quite electropositive and reacts slowly with cold water and quite quickly with hot water to form promethium hydroxide:

2 Pm (s) + 6 H2O (l) → 2 Pm(OH)3 (aq) + 3 H2 (g)

Promethium metal reacts with all the halogens:

2 Pm (s) + 3 F2 (g) → 2 PmF3 (s)
2 Pm (s) + 3 Cl2 (g) → 2 PmCl3 (s)
2 Pm (s) + 3 Br2 (g) → 2 PmBr3 (s)
2 Pm (s) + 3 I2 (g) → 2 PmI3 (s)

Promethium(III) iodide may also be synthesized by reacting PmX3 (X = Cl, Br) with hydrogen iodide at 400 °C:

2 PmX3(s) + 3HI(g) → PmI3(s) + 3HX(g)

Promethium dissolves readily in dilute sulfuric acid to form solutions containing the pink Pm(III) ions, which exist as a [Pm(OH2)9]3+ complexes:[20]

2 Pm(s) + 3 H2SO4 (aq) → 2 Pm3+ (aq) + 3 (SO4)2- (aq) + 3 H2 (g)

Promethium(III) ions form an insoluble, hygroscopic oxalate when dissolved in aqueous H2C2O4:

2 Pm3+(aq) + C2O42- (aq) → Pm2(C2O4)3•xH2O(s)

Applications

Promethium being used as a light source for signals in a heat button.

Uses for promethium include:

Precautions

Promethium must be handled with great care because of its high radioactivity. In particular, promethium can emit X-rays during its beta decay. It is expected to have biological toxicity comparable with beta emitters of similar half-life, for example iodine-131. It is not as hazardous as alpha emitters such as the transuranics, due to the far lower relative biological effectiveness of beta emitters over alpha emitters. Promethium has no biological role.

Compounds

Promethium compounds include:

References

  1. ^ Magnetic susceptibility of the elements and inorganic compounds, in Handbook of Chemistry and Physics 81st edition, CRC press.
  2. ^ a b Laing, Michael (2005). "A Revised Periodic Table: With the Lanthanides Repositioned". Foundations of Chemistry 7 (3): 203–233. doi:10.1007/s10698-004-5959-9.
  3. ^ a b American Chemical Society, "Separation of Rare Earth Elements"
  4. ^ Rolla, Luigi; Fernandes, Lorenzo (1926). "Über das Element der Atomnummer 61". Zeitschrift für anorganische und allgemeine Chemie 157: 371. doi:10.1002/zaac.19261570129.
  5. ^ Noyes, W. A. (1927). "Florentium or Illinium?". Nature 120 (3009): 14. Bibcode 1927Natur.120...14N. doi:10.1038/120014c0.
  6. ^ Rolla, L.; Fernandes, L. (1927). "Florentium or Illinium?". Nature 119 (3000): 637. Bibcode 1927Natur.119..637R. doi:10.1038/119637a0.
  7. ^ Rolla, Luigi; Fernandes, Lorenzo (1928). "Florentium. II". Zeitschrift für anorganische und allgemeine Chemie 169: 319. doi:10.1002/zaac.19281690128.
  8. ^ Rolla, Luigi; Fernandes, Lorenzo (1927). "Florentium". Zeitschrift für anorganische und allgemeine Chemie 163: 40. doi:10.1002/zaac.19271630104.
  9. ^ Rolla, Luigi; Fernandes, Lorenzo (1927). "Über Das Element der Atomnummer 61 (Florentium)". Zeitschrift für anorganische und allgemeine Chemie 160: 190. doi:10.1002/zaac.19271600119.
  10. ^ Harris, J. A.; Yntema, L. F.; Hopkins, B. S. (1926). "The Element of Atomic Number 61; Illinium". Nature 117 (2953): 792. Bibcode 1926Natur.117..792H. doi:10.1038/117792a0.
  11. ^ Brauner, BOHUSLAV (1926). "The New Element of Atomic Number 61: Illinium". Nature 118 (2959): 84. Bibcode 1926Natur.118...84B. doi:10.1038/118084b0.
  12. ^ Meyer, R. J.; Schumacher, G.; Kotowski, A. (1926). "Über das Element 61 (Illinium)". Naturwissenschaften 14: 771. Bibcode 1926NW.....14..771M. doi:10.1007/BF01490264.
  13. ^ "Discovery of Promethium". ORNL Review 36 (1). 2003. http://www.ornl.gov/info/ornlreview/v36_1_03/article_02.shtml. Retrieved 2006-09-17.
  14. ^ Lee, Chung-Sin; Wang, Yun-Ming; Cheng, Wu-Long; Ting, Gann (1989). "Chemical study on the separation and purification of promethium-147". Journal of Radioanalytical and Nuclear Chemistry Articles 130: 21. doi:10.1007/BF02037697.
  15. ^ "ION EXCHANGE PURIFICATION OF PROMETHIUM-147 AND ITS SEPARATION FROM AMERICIUM-241, WITH DIETHYLENETRIAMINEPENTA-ACETIC ACID AS THE ELUANT". http://www.ornl.gov/info/reports/1962/3445605484259.pdf.
  16. ^ Attrep, Moses, Jr.; and P. K. Kuroda (May 1968). "Promethium in pitchblende". Journal of Inorganic and Nuclear Chemistry 30 (3): 699–703. doi:10.1016/0022-1902(68)80427-0.
  17. ^ 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 (2007). "Search for α decay of natural Europium". Nuclear Physics A 789: 15–29. Bibcode 2007NuPhA.789...15B. doi:10.1016/j.nuclphysa.2007.03.001.
  18. ^ C. R. Cowley, W. P. Bidelman, S. Hubrig, G. Mathys, and D. J. Bord (2004). "On the possible presence of promethium in the spectra of HD 101065 (Przybylski's star) and HD 965". Astronomy & Astrophysics 419: 1087–1093. Bibcode 2004A&A...419.1087C. doi:10.1051/0004-6361:20035726.
  19. ^ a b c G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties". Nuclear Physics A 729: 3–128. Bibcode 2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf.
  20. ^ "Chemical reactions of Promethium". Webelements. https://www.webelements.com/promethium/chemistry.html. Retrieved 2009-06-06.

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· · Periodic table
H He
Li Be B C N O F Ne
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K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
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** Actinides Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr
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