promethium

American  

[pruh-mee-thee-uhm] / prəˈmi θi əm /

noun

Chemistry.

1. a rare-earth, metallic, trivalent element. Pm; 61.

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promethium British  

/ prəˈmiːθɪəm /

noun

1. a radioactive element of the lanthanide series artificially produced by the fission of uranium. Symbol: Pm; atomic no: 61; half-life of most stable isotope, ¹⁴⁵ Pm: 17.7 years; valency: 3; melting pt: 1042°C; boiling pt: 2460°C (approx.)

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promethium Scientific  

/ prə-mē′thē-əm /

1. A radioactive metallic element of the lanthanide series. Promethium does not occur in nature but is prepared through the fission of uranium. It has 17 isotopes, one of which is used to make long-lived miniature batteries that work at extreme temperatures for up to five years. The longest-lived isotope, Pm 147, has a half-life of 2.5 years and is used as a source of beta rays. Atomic number 61; melting point 1,168°C; boiling point 2,460°C; valence 3.

2. See Periodic Table

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Etymology

Origin of promethium

From New Latin, dating back to 1945–50; see origin at Prometheus, -ium

Example Sentences

See Examples For:

promethium

"Because it has no stable isotopes, promethium was the last lanthanide to be discovered and has been the most difficult to study," said ORNL's Ilja Popovs, who co-led the research.

From Science Daily ● May 22, 2024

Unlike other rare earth elements, only minute quantities of synthetic promethium are available because it has no stable isotopes.

From Science Daily ● May 22, 2024

Experimenting with elements created by the Manhattan Project, researchers realized that they could create two different versions, or isotopes, of promethium, the sixty-first atom on the periodic table.

From The New Yorker ● Dec. 27, 2019

One promethium isotope, with eighty-eight neutrons, has a half-life of a few days; the other, with eighty-six neutrons, has a half-life of a few years.

From The New Yorker ● Dec. 27, 2019

Compare the resonance of einsteinium and promethium to chromosome 7 and chromosome 21.

From Slate ● Jul. 9, 2012