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Radioactive isotope table "lists ALL radioactive nuclei with a half-life greater than 1000 years", incorporated in the list above. The NUBASE2020 evaluation of nuclear physics properties F.G. Kondev et al. 2021 Chinese Phys. C 45 030001. The PDF of this article lists the half-lives of all known radioactives nuclides.
There is a half-life describing any exponential-decay process. For example: As noted above, in radioactive decay the half-life is the length of time after which there is a 50% chance that an atom will have undergone nuclear decay. It varies depending on the atom type and isotope, and is usually determined experimentally. See List of nuclides.
At least 3,300 nuclides have been experimentally characterized [1] (see List of radioactive nuclides by half-life for the nuclides with decay half-lives less than one hour). A nuclide is defined conventionally as an experimentally examined bound collection of protons and neutrons that either is stable or has an observed decay mode .
A chart or table of nuclides maps the nuclear, or radioactive, behavior of nuclides, as it distinguishes the isotopes of an element.It contrasts with a periodic table, which only maps their chemical behavior, since isotopes (nuclides that are variants of the same element) do not differ chemically to any significant degree, with the exception of hydrogen.
This is the longest half-life directly measured for any unstable isotope; [4] only the half-life of tellurium-128 is longer. [ citation needed ] Of the chemical elements, only 1 element ( tin ) has 10 such stable isotopes, 5 have 7 stable isotopes, 7 have 6 stable isotopes, 11 have 5 stable isotopes, 9 have 4 stable isotopes, 5 have 3 stable ...
The longest lived, and most common, isotope of radium is 226 Ra with a half-life of 1600 years. 226 Ra occurs in the decay chain of 238 U (often referred to as the radium series). Radium has 34 known isotopes from 201 Ra to 234 Ra.
The longest-lived of these is 133 Ba, which has a half-life of 10.51 years. All other radioisotopes have half-lives shorter than two weeks. The longest-lived isomer is 133m Ba, which has a half-life of 38.9 hours. The shorter-lived 137m Ba (half-life 2.55 minutes) arises as the decay product of the common fission product caesium-137.
The low decay energy, lack of gamma radiation, and long half-life of 135 Cs make this isotope much less hazardous than 137 Cs or 134 Cs. Its precursor 135 Xe has a high fission product yield (e.g., 6.3333% for 235 U and thermal neutrons ) but also has the highest known thermal neutron capture cross section of any nuclide.