Promethium is a chemical element that is radioactive and is denoted by the symbol Pm with the atomic number of 61. Promethium was first found by Jacob A. Marinsky, Lawrence E. Glendenin and Charles D. Coryell in 1945 at Oak Ridge National University. It was discovered through the separation and analysis of fission products of uranium fuel irradiated in the graphite reactor.

1. It was named after the Greek titan Prometheus. Prometheus stole fire from mount Olympus and brought it down to mankind. The name was suggested by Charles D. Coryell’s wife, Grace Mary Coryell.

2. It is classified as a rare earth element, part of the Lanthanide series. The elements in this series closely resemble each other in their physical and chemical properties. Their compounds are also used as catalysts in the production of petroleum products.

3. Promethium is not naturally found on earth, and the common uses include nuclear batteries and light sources (luminous watches have promethium in them, that’s what makes them glow in the dark). Other applications are uses as a beta radiation source for thickness gauges, and future uses include portable X ray sources, as well as auxiliary heat and power sources for space probes and satellites.

4. Pure promethium is found in two allotropic forms, and they glow with a pale blue or greenish glow due to its radioactivity.

5. Promethium has been classified into thirty-six radioisotopes, the most stable is 145Pm with a half-life of 17.7 years, 146Pm with a half-life of 5.53 years, and 147Pm with a half-life of 2.6234 years.

6. Promethium burns at 150 °C and is slow reacting with cold water; however it forms promethium hydroxide in hot water. It dissolves in sulfuric acid to form solutions containing pink Pm ions. The ions form an insoluble, hygroscopic oxalate when dissolved in aqueous solutions.

7. Due to promethium being highly radioactive, it Is supposed to be handled with the utmost of care; it can even emit x rays during its beta decay and has a biological toxicity comparable with beta emitters of similar half lives like iodine-131.

8. Compounds of promethium include; Chlorides {(PmCl3 (lavender)}, Bromides {PmBr3 (coral - red)}, Fluorides {PmF3 (purple - pink)}, Nitrates {Pm (NO3)3}, Oxalates {Pm2(C2O4)3}, and Oxides {Pm2O3}.

9. Promethium has a density of around 7.26 g•cm−3, the melting point being 1908 °F, while the boiling point is at 5432 °F, its heat of fusion is at 7.13 kJ•mol−1, while the heat of vaporization is 289 kJ•mol−1 , it has three oxidation states and an electronegativity of 1.13 on the Pauling scale. The ionization energies are 540 kJ•mol−1 for the first, 1050 kJ•mol−1 for the second and 2150 kJ•mol−1 for the third. The atomic radius is 183 pm while the covalent radius is 1 99 pm.

10. However promethium is no longer preferred in the use of glow in the dark substances, and tritium has taken its place being less harmful and for various other safety concerns. Promethium is an exotic element, and has been identified in the spectrum of the star HR 465 in Andromeda.