- Bismuth-209
Bismuth-209 is the most stable
isotope ofbismuth . It has 83 protons and 126 neutrons, and an atomic mass of 208.9803987. All naturally occurring bismuth is of this isotope. It is a decay product fromLead-209 decaying by β--decay.Bismuth-209 was long thought to have the heaviest stable nucleus of any element, but in 2003
Noël Coron and colleagues at theInstitut d’Astrophysique Spatiale inOrsay, France discovered that it underwentalpha decay with a half-life of approximately 19 exayears (1.9e|19 years), over a billion times longer than the current estimatedage of the universe . Theory had previously predicted a half-life of 4.6e|19 years. The decay event produces a 3.14 MeValpha particle and converts the atom tothallium-205 . [cite news| url=http://physicsweb.org/articles/news/7/4/16| title=Bismuth breaks half-life record for alpha decay| date=2003-04-23| publisher=Physicsweb| first=Belle| last= Dumé] [cite journal | last = Marcillac | first = Pierre de | coauthors = Noël Coron, Gérard Dambier, Jacques Leblanc, and Jean-Pierre Moalic | year = 2003 | month = April | title = Experimental detection of α-particles from the radioactive decay of natural bismuth | journal = Nature | volume = 422 | pages = 876–878 | doi = 10.1038/nature01541 ]Due to its extraordinarily long half-life, for nearly all applications bismuth can still be treated as if it is stable and non-radioactive.
References
ee also
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Isotopes of bismuth
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