Promethium(III) chloride

Glowing powder mixture of promethium(III) chloride and zinc sulfide

Crystal structure
Names
Other names
Promethium chloride; Promethium trichloride
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.034.004 Edit this at Wikidata
EC Number
  • 237-420-0
  • InChI=1S/3ClH.Pm/h3*1H;/q;;;+3/p-3
    Key: KAKNBYVEBALXNX-UHFFFAOYSA-K
  • [Cl-].[Cl-].[Cl-].[Pm+3]
Properties
Cl3Pm
Molar mass 251 g·mol−1
Density 4.19 g/cm3 (calc., XRD)[1]
Melting point 655 °C (1,211 °F; 928 K)[2]
Structure
Trigonal, hP8
P63/m, No. 176[1]
Related compounds
Other anions
 Promethium(III) oxide
Other cations
 Neodymium(III) chloride, Samarium(III) chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Promethium(III) chloride is a chemical compound of promethium and chlorine with the formula PmCl3. It is an ionic, water soluble, crystalline salt that glows in the dark with a pale blue or green light due to promethium's intense radioactivity.

Preparation

Promethium(III) chloride is obtained from promethium(III) oxide by heating it in a stream of dry HCl at 580 °C.[3]

Properties

Promethium(III) chloride is a purple solid with a melting point of 655 °C.[4] It crystallizes in the hexagonal crystal system (NdCl3 type) with the lattice parameters a = 739 pm and c = 421 pm with two formula units per unit cell and thus a calculated density of 4.19 g·cm−3.[5][6] When PmCl3 is heated in the presence of H2O, the pale pink colored promethium(III) oxychloride (PmOCl) is obtained.[5][7]

Applications

Promethium(III) chloride (with 147Pm) has been used to generate long-lasting glow in signal lights and buttons. This application relied on the unstable nature of promethium, which emitted beta radiation (electrons) with a half-life of several years. The electrons were absorbed by a phosphor, generating visible glow.[8] Unlike many other radioactive nuclides, promethium-147 does not emit alpha particles that would degrade the phosphor.[9]

References

  1. ^ a b Weigel, F.; Scherer, V. (1967). "Die Chemie des Promethiums". Radiochimica Acta. 7. doi:10.1524/ract.1967.7.1.40. S2CID 201840710.
  2. ^ Haynes, William M., ed. (2011). CRC Handbook of Chemistry and Physics (92nd ed.). Boca Raton, FL: CRC Press. p. 4.84. ISBN 1-4398-5511-0.
  3. ^ Gmelins Handbuch der anorganischen Chemie, System No. 39, p. 61–62.
  4. ^ Wiberg, Egon; Wiberg, Nils (2007). Holleman, Arnold F.; Fischer, Gerd (eds.). Lehrbuch der anorganischen Chemie (102., stark umgearbeitete und verbesserte Auflage ed.). Berlin New York: Walter de Gruyter. ISBN 978-3-11-017770-1.
  5. ^ a b Weigel: Die Chemie des Promethiums, p. 588–589.
  6. ^ Gmelins Handbuch der anorganischen Chemie, System No. 39, p. 181.
  7. ^ Gmelins Handbuch der anorganischen Chemie, System No. 39, p. 31.
  8. ^ Haynes, William M., ed. (2011). CRC Handbook of Chemistry and Physics (92nd ed.). Boca Raton, FL: CRC Press. p. 4.28. ISBN 1-4398-5511-0.
  9. ^ Lavrukhina, Avgusta Konstantinovna; Pozdnyakov, Aleksandr Aleksandrovich (1966). Аналитическая химия технеция, прометия, астатина и франция [Analytical Chemistry of Technetium, Promethium, Astatine, and Francium] (in Russian). Nauka. p. 118.


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