- a radioactive element of the alkali metal group. Symbol: Fr; atomic number: 87.
Origin of francium
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Examples from the Web for francium
The last of the original 92 elements to be discovered was element 87, francium.
- 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
C20: from New Latin, from France + -ium; so-called because first found in France
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
- An extremely unstable radioactive element of the alkali metals, having approximately 19 isotopes, the most stable of which is Fr 223 with a half-life of 21 minutes. Atomic number 87.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
- 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. See Periodic Table.
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