|Isotope mass||208.9803987 u|
|Excess energy||−18 258.461± 2.4 keV|
|Binding energy||7847.987± 1.7 keV|
|Decay mode||Decay energy (MeV)|
|Complete table of nuclides|
Bismuth-209 is the "quasi-stable" isotope of bismuth with the longest known half-life of any radioisotope that undergoes α-decay (alpha decay). It has 83 protons and a magic number of 126 neutrons, and an atomic mass of 208.9803987 amu (atomic mass units). All of the primordial bismuth is of this isotope. It is also the β− daughter of lead-209.
Bismuth-209 was long thought to have the heaviest stable nucleus of any element, but in 2003, Noël Coron and his colleagues at the Institut d’Astrophysique Spatiale in Orsay, France, discovered that 209Bi undergoes alpha decay with a half-life of approximately 19 exayears (1.9×1019 which is 19 quintillion years), over a billion times longer than the current estimated age of the universe. Theory had previously predicted a half-life of 4.6×1019 years. The decay event produces a 3.14 MeV alpha particle and converts the atom to thallium-205.
Bismuth-209 will eventually form 205Tl:
Due to its extraordinarily long half-life, for nearly all applications 209Bi can still be treated as if it were non-radioactive. Although 209Bi holds the half-life record for alpha decay, bismuth does not have the longest half-life of any radionuclide to be found experimentally—this distinction belongs to tellurium-128 (128Te) with a half-life estimated at 7.7 x 1024 years by double β-decay (beta decay).
In the red giant stars of the asymptotic giant branch, the s-process (slow process) is ongoing to produce bismuth-209 and polonium-210 by neutron capture as the heaviest elements to be formed, and the latter quickly decays. All elements heavier than it are formed in the r-process, or rapid process, which occurs during the first fifteen minutes of supernovas.
|Bismuth-209 is an
isotope of bismuth
|Decay product of:
|Decays to: |
- Dumé, Belle (2003-04-23). "Bismuth breaks half-life record for alpha decay". Physicsweb.
- Marcillac, Pierre de; Noël Coron; Gérard Dambier; Jacques Leblanc; Jean-Pierre Moalic (April 2003). "Experimental detection of α-particles from the radioactive decay of natural bismuth". Nature. 422 (6934): 876–878. Bibcode:2003Natur.422..876D. doi:10.1038/nature01541. PMID 12712201.
- "Archived copy". Archived from the original on 2011-09-28. Retrieved 2013-01-10. Tellurium-128 information and half-life. Accessed July 14, 2009.
- "Swiss study: Polonium found in Arafat's bones". Al Jazeera. Retrieved 2013-11-07.
- Chaisson, Eric, and Steve McMillan. Astronomy Today. 6th ed. San Francisco: Pearson Education, 2008.