Sinonimi: Pm | atomic number 61
Radioactive, metallic element of the lanthanide series, symbol Pm, atomic number 61, atomic weight 145.
It occurs in nature only in minute amounts, produced as a fission product/by-product of uranium in pitchblende and other uranium ores; for a long time it was considered not to occur in nature. The longest-lived isotope has a half-life of slightly more than 20 years.
Promethium is synthesized by neutron bombardment of neodymium, and is a product of the fission of uranium, thorium, or plutonium; it can be isolated in large amounts from the fission-product debris of uranium fuel in nuclear reactors. It is used in phosphorescent paints and as an X-ray source.
It was named in 1949 after the Greek Titan Prometheus by G M Coryell for the element isolated by US physicists J A Marinsky and L E Glendenin.A soft silvery metallic element of the rare earth group having no stable isotope; was discovered in radioactive form as a fission product of uranium; SYN. Pm, atomic number 61.