Discovery date : 1945
Discovered by: Jacob .A. Marinsky, Lawrence E. Glendenin, and Charles D. Coryell
Origin of the name: Promethium is named after Prometheus of Greek mythology
who stole fire from the Gods and gave it to humans.
Allotropes :
~>PROMETHIUM (formerly prometheum) is a chemical element with symbol Pm and atomic number 61. All of its isotopes are radioactive; it is one of only two such elements that are followed in the periodic table by elements with stable forms, a distinction shared with technetium.
| FACT BOX | |||
| Group | Lanthanides | Melting point | 1042°C, 1908°F, 1315 K |
| Period | 6 | Boiling point | 3000°C, 5432°F, 3273 K |
| Block | f | Density (g cm−3) | 7.26 |
| Atomic number | 61 | Relative atomic mass | [145] |
| State at 20°C | Solid | Key isotopes | 145Pm,147Pm |
| Electron configuration | [Xe] 4f56s2 | CAS number | 7440-12-2 |
| ChemSpider ID | 22386 | ChemSpider is a free chemical structure database | |
In 1902, Bohuslav Branner speculated that there should be an element in the periodic table between neodymium and samarium. He was not to know that all its isotopes were radioactive and had long disappeared. Attempts were made to discover it and several claims were made, but clearly all were false. However, minute amounts of promethium do occur in uranium ores as a result of nuclear fission, but in amounts of less than a microgram per million tonnes of ore.
In 1939, the 60-inch cyclotron at the University of California was used to make promethium, but it was not proven. Finally element 61 was produced in 1945 by Jacob .A. Marinsky, Lawrence E. Glendenin, and Charles D. Coryell at Oak Ridge, Tennessee. They used ion-exchange chromatography to separate it from the fission products of uranium fuel taken from a nuclear reactor.