Promethium

There are three possible sources for promethium: rare decays of natural neodymium (producing promethium-150), europium (promethium-147), and uranium (various isotopes). The most stable isotope, promethium-145, has a very low rate of alpha decay, so that the alpha half-life is long enough for the presence of primordial promethium to be theoretically possible; however, this has not been experimentally confirmed. The only isotope used in industry is promethium-147, which is used in radioionizators, light producers, and atomic batteries, the last of these are used in guided missiles. Since natural promethium is exceedingly scarce, the element is typically man-made by bombarding uranium-235 with thermal neutrons.
 * Promethium** originally **prometheum**, is a chemical element with the symbol **Pm** and atomic number 61. It is notable for being the only element besides technetium all of whose isotopes are radioactive but which is followed in the periodic table by chemical elements with stable isotopes. Chemically, promethium is a lanthanide, which forms salts when combined with other elements; the compounds, however, have not been fully studied. Promethium shows only one stable oxidation state of +3; however, a few +2 compounds may be capable of existence. In 1902, Bohuslav Brauner suggested there was an element with properties intermediate between those of the known elements neodymium (60) and samarium (62); this was confirmed in 1914 by Henry Moseley who, having measured the atomic numbers of all the elements then known, found there was no element with atomic number 61. In 1926, an Italian and an American group claimed to have isolated a sample of element 61; both "discoveries" were soon proven to be false. In 1938, during a nuclear experiment conducted at Ohio State University, a few radioactive nuclides were produced that certainly were not radioisotopes of neodymium or samarium, but there was a lack of chemical proof that element 61 was produced, and the discovery was not generally recognized. Promethium was first produced and characterized at Oak Ridge National Laboratory in 1945 by the separation and analysis of the fission products of uranium fuel irradiated in a graphite reactor. The discoverers proposed the name "prometheum" (the spelling was subsequently changed), derived from Prometheus, the Titan in Greek mythology, who stole fire from Mount Olympus and brought it down to mankind, to symbolize "both the daring and the possible misuse of mankind's intellect." However, a sample of the metal was made only in 1963.


 * Harmful effects: ** Promethium is harmful due to its radioactivity.
 * Characteristics: ** Promethium is the only rare earth radioactive metal. In the dark, its salts luminesce with a pale blue or green glow due to its high radioactivity. Isotope 147Pm, the most useful isotope, decays with with energetic gamma rays.

Uses of Promethium
Promethium is useful as a beta source for thickness gauges. Promethium is also used in atomic batteries for spacecraft and guided missiles.



The element, like other lanthanides, has no biological role. Promethium-147 can emit X-rays during its beta decay,[48home] which are dangerous for all lifeforms. Interactions with tiny quantities of promethium-147 are not hazardous if certain precautions are observed.[49home] In general, gloves, footwear covers, safety glasses, and an outer layer or easily removed protective clothing should be used.[50home] It is not known what human organs are affected by interaction with promethium; a possible candidate is the bone tissues.[50home] Sealed promethium-147 is not dangerous. However, if the packaging is damaged, then promethium becomes dangerous to the environment and humans. If radioactive contamination is found, the contaminated area should be washed with water and soap, but, even though promethium mainly affects the skin, the skin should not be ripped off. If a promethium leak is found, the area should be identified as hazardous and evacuated, and emergency services must be contacted.[50home] No dangers aside from the radioactivity have been shown.[50home]