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; -ium

Example Sentences

Perey, being French, decided to call it francium instead.

From The New Yorker • Dec. 27, 2019

Lithium, sodium and potassium, which nicely align in the table’s first vertical column — Group One, the alkali metals, with rubidium, cesium, and francium — all have one electron in their outer electron shell.

From New York Times • Aug. 27, 2019

In 1939 she isolated francium, the 87th element in the periodic table.

From Time Magazine Archive

The last of the original 92 elements to be discovered was element 87, francium.

From A Brief History of Element Discovery, Synthesis, and Analysis by Watson, Glen W.