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Francium-223 is the most stable isotope, with a half-life of 21.8 minutes, [8] and it is highly unlikely that an isotope of francium with a longer half-life will ever be discovered or synthesized. [22] Francium-223 is a fifth product of the uranium-235 decay series as a daughter isotope of actinium-227; thorium-227 is the more common daughter. [23]
Francium (87 Fr) has no stable isotopes, thus a standard atomic weight cannot be given. Its most stable isotope is 223 Fr with a half-life of 22 minutes, occurring in trace quantities in nature as an intermediate decay product of 235 U. Of elements whose most stable isotopes have been identified with certainty, francium is the most unstable.
Francium compounds are compounds containing the element francium (Fr). Due to francium being very unstable, its salts are only known to a small extent. Francium coprecipitates with several caesium salts, such as caesium perchlorate, which results in small amounts of francium perchlorate.
Perey named the element francium, after her home country, and it joined the other alkali metals in Group 1 of the periodic table of elements. [3] [7] Francium is the second rarest element (after astatine) — only about 550g exists in the entire Earth's crust at any given time — and it was the last element to be discovered in nature.
Most of its isotopes are very unstable, with half-lives of seconds or less. Of the first 101 elements in the periodic table, only francium is less stable, and all the astatine isotopes more stable than the longest-lived francium isotopes (205–211 At) are in any case synthetic and do not occur in nature. [6]
The claim that francium has a lower electronegativity than caesium is widely, though not universally, repeated: this would be expected on the basis of periodicity, but measurements show that the ionization energy of francium is higher (4.0712 eV; Andreev, S.V.; Letokhov, V.S.; Mishin, V.I., Laser resonance photoionization spectroscopy of ...
Francium compounds This page was last edited on 23 October 2017, at 22:31 (UTC). Text is available under the Creative Commons Attribution-ShareAlike 4.0 ...
This page lists radioactive nuclides by their half-life.