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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-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]
astatine-223: 50 francium-229: 50.2 lead-189m1: 50.5 nobelium-254: 51 ... The NUBASE2020 evaluation of nuclear physics properties F.G. Kondev et al. 2021 Chinese Phys ...
From Wikipedia, the free encyclopedia. Redirect page. Redirect to: Isotopes of francium#Francium-223
An even number of protons or neutrons is more stable (higher binding energy) because of pairing effects, so even–even nuclides are much more stable than odd–odd. One effect is that there are few stable odd–odd nuclides: in fact only five are stable, with another four having half-lives longer than a billion years.
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This page uses the meta infobox {{Infobox isotopes (meta)}} for the element isotopes infobox.. This infobox contains the table of § Main isotopes, and the § Standard atomic weight.
Francium was the last element discovered in nature, rather than synthesized. Outside the laboratory, francium is extremely rare, with trace amounts found in uranium and thorium ores, where the isotope francium-223 is continually formed and continually decays.