promethium
Noun 1. A radioactive metallic chemical element: Promethium is a soft, silvery-white metal that belongs to the lanthanide series (rare earth group) on the periodic table. Its key characteristic is that it has no stable isotopes; all its forms are radioactive. 2. A synthetic or fission product element: It is not found naturally in significant quantities on Earth. It is produced artificially, typically as a product of nuclear fission in reactors or from the decay of other radioactive elements like uranium.
- Scientific Context:
- The sample contained traces of promethium, which required careful handling in the shielded lab.
- Scientists studied the decay chain of uranium and identified promethium as one of the fission products.
- Descriptive Context:
- Due to its radioactivity, promethium is used in specialized applications like atomic batteries.
- "Promethium-147": This refers to the most common and useful isotope of promethium, which has a half-life of about 2.6 years and emits beta particles. It is specified in technical contexts.
- The luminous paint used promethium-147 as its radiation source.
- Pm: The standard chemical symbol for promethium (atomic number 61).
- The element Pm is positioned between neodymium and samarium on the periodic table.
- Element 61: A synonym based on its atomic number.
- (A) lanthanide / rare-earth metal: Categorical synonyms describing its group in the periodic table, though these terms are broader and include many other elements.
The definition of promethium is highly specific to chemistry and physics. It does not have idiomatic meanings or phrasal verbs associated with it in everyday language. Its usage is almost exclusively technical, relating to its properties as a radioactive, synthetic, rare-earth metal.
- 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