noun
- a radioactive metallic chemical element with the symbol Pm and atomic number 61
Usage: chemistry
Examples
- Promethium is the only radioactive element in the lanthanide series.
- Scientists first produced promethium artificially in 1945.
- Promethium-147 is used in some luminous paints and nuclear batteries.
- The element promethium does not occur naturally on Earth.
- Promethium has a relatively short half-life compared to other elements.
- Research facilities handle promethium with special safety precautions.