What Promethium looks like.
Prediction
The existence of promethium was first predicted by Bohuslav Brauner
in 1902. 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. 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. With the knowledge of a gap in the periodic table several
groups started to search for the predicted element among other rare
earths in natural environment.
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. The name promethium is derived from Prometheus, the Titan, in
Greek mythology, who stole the 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.
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
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. It was
calculated that the equilibrium mass of promethium in the earth's
crust is about 560 g due to uranium fission and about 12 g due to
the recently observed alpha decay of europium-151.
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.
Precautions
Promethium must be handled with great care because of its high
radioactivity. In particular, promethium can emit X-rays during its
beta decay. Its half-life is less than that of plutonium-239 by a
factor of about 1350, and its biological toxicity is
correspondingly higher. Promethium has no biological role.
PERIODIC TABLE
Check out this interactive Periodic Table.
Check out this Promethium video. Prepared by The University of
Nottingham.