The chemical element of atomic number 61, a radioactive metal of the lanthanide series. It was first produced artificially in a nuclear reactor and occurs in nature in traces as a product of uranium fission.‘Finally in 1945, scientists isolated promethium from uranium fission products purified by ion-exchange chromatography.’
- ‘In fact, the elements with atomic numbers 43, 61, and 85 (technetium, promethium, and astatine, respectively) were unknown on earth until some of their radioactive isotopes had been produced synthetically.’
- ‘The only missing one was element number 61, which was eventually isolated from the debris of the radioactive decay of uranium and given the name of promethium, after the Greek god who gave man fire.’
1940s modern Latin, from the name of the Titan Prometheus.