francium

American  

[fran-see-uhm] / ˈfræn si əm /

noun

Chemistry.

1. a radioactive element of the alkali metal group. Fr; 87.

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francium British  

/ ˈfrænsɪəm /

noun

1. an unstable radioactive element of the alkali-metal group, occurring in minute amounts in uranium ores. Symbol: Fr; atomic no: 87; half-life of most stable isotope, ²²³ Fr: 22 minutes; valency: 1; melting pt: 27°C; boiling pt: 677°C

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francium Scientific  

/ frăn′sē-əm /

1. An extremely unstable, radioactive element of the alkali group. It is the heaviest metal of the group. Francium occurs in nature, but less than 28.35 g (1 oz) is present in the Earth's crust at any time. It has approximately 19 isotopes, the most stable of which is Fr 223 with a half-life of 21 minutes. Atomic number 87; valence 1.

2. See Periodic Table

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Etymology

Origin of francium

1945–50; after France where first identified; see -ium

Example Sentences

The New York Times Magazine Veronique Greenwood talks about the sacrifice often inherent to scientific discovery, and recounts Marguerite Perey's discovery of Francium.

From The Verge • Dec. 6, 2014