Atomic Number: 61
Atomic Symbol: Pm
Atomic Weight: 145
Melting Point: 1,907.6 F (1,042 C)
Boiling Point: 5,432.2 F (3,000 C)
Word origin: Prometheus, who robbed fire from heaven according to Greek mythology, is the namesake for this element.
Discovery: Promethium was discovered by Bohuslav Brauner, a Czech chemist, who forecast the existence of promethium, an element between neodymium and samarium. British physicist Henry Moseley confirmed the discovery in 1914. A new group of radioactives, which most likely included those of element 61, was produced when workers at Ohio State University irradiated neodymium and praseodymium with neutrons, deuterons and alpha particles in 1941. Jacob A. Marinsky, Lawrence E. Glendenin and Charles D. Coryell madethe first chemical identification in 1944 by fission of uranium and by neutron bombardment of neodymium.
Properties of promethium
Promethium is one of the lanthanides, which have similar chemical properties. The handling of promethium requires extreme care as X-radiation can be generated when beta particles impinge on elements of a high atomic number. [See Periodic Table of the Elements]
Due to their radioactivity, promethium salts emit a pale blue or greenish glow in the dark. In early 1963, about 10 grams of promethium from atomic reactor fuel processing wastes were produced through ion-exchange methods. Two allotropic modifications of the element exist, although not much is known about the properties of metallic promethium.
Sources of promethium
Although completely gone from Earth’s crust, promethium has been identified in the spectrum of the star HR465 in the constellation Andromeda. The formation is recent because no known isotope of promethium has a half-life longer than 17.7 years
Today, promethium is still recovered from the byproducts of uranium fission. It can also be produced by bombarding neodymium-146 with neutrons.
Seventeen isotopes of promethium, with atomic masses from 134 to 155, are known. Promethium-147, with a half-life of 2.6 years, is the most generally useful.
Uses of promethium
The element has applications as a beta source for thickness gages, and it can be absorbed by a phosphor to produce light for signs or signals. It can be used as a nuclear-powered battery by capturing light in photocells which convert it into electric current.
The earliest pacemakers were powered by nuclear batteries that used promethium.
Promethium shows promise as a portable X-ray source, and it may become useful as a heat source to provide auxiliary power for space probes and satellites.
(Source: Los Alamos National Laboratory)