Isotopes of francium
Open-knowledge reference entry
Francium (87Fr) has no stable isotopes, so a standard atomic weight cannot be given. Its most stable isotope is 223Fr with a half-life of 22 minutes, occurring in trace quantities in nature as an intermediate decay product of 235U.
Of elements whose most stable isotopes have been identified with certainty, francium is the most unstable, though astatine is the rarest in nature due to its naturally occurring isotopes having even shorter half-lives and even smaller branching ratios.
In the case of all elements with atomic number 106 (seaborgium) and above, no isotopes have been discovered whose half-life exceeds that of francium-223. However, the isotopes of these elements so far discovered are all on the proton-rich side of beta stability; so there is a strong possibility that some undiscovered isotopes of these elements will have longer half-lives, which could exceed that of francium-223.
List of isotopes
References
Half-life, spin, and isomer data selected from the following sources.
Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
National Nuclear Data Center. "NuDat 3.0 database". Brookhaven National Laboratory.
Holden, Norman E. (2004). "11.
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