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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.
Uranium-234 is a member of the uranium series and occurs in equilibrium with its progenitor, 238 U; it undergoes alpha decay with a half-life of 245,500 years [7] and decays to lead-206 through a series of relatively short-lived isotopes. Uranium-233 undergoes alpha decay with a half-life of 160,000 years and, like 235 U, is fissile. [12]
All three isotopes are radioactive (i.e., they are radioisotopes), and the most abundant and stable is uranium-238, with a half-life of 4.4683 × 10 9 years (about the age of the Earth). Uranium-238 is an alpha emitter, decaying through the 18-member uranium series into lead-206.
Around 99.284% of natural uranium's mass is uranium-238, which has a half-life of 1.41 × 10 17 seconds (4.468 × 10 9 years, or 4.468 billion years). [1] Due to its natural abundance and half-life relative to other radioactive elements, 238 U produces ~40% of the radioactive heat produced within the Earth. [2]
Uranium-235 (235 U or U-235) is an isotope of uranium making up about 0.72% of natural uranium. Unlike the predominant isotope uranium-238, it is fissile, i.e., it can sustain a nuclear chain reaction. It is the only fissile isotope that exists in nature as a primordial nuclide. Uranium-235 has a half-life of 703.8 million years.
The three long-lived nuclides are uranium-238 (half-life 4.5 billion years), uranium-235 (half-life 700 million years) and thorium-232 (half-life 14 billion years). The fourth chain has no such long-lasting bottleneck nuclide near the top, so almost all of the nuclides in that chain have long since decayed down to just before the end: bismuth-209.
[c] For a list of primordial nuclides in order of half-life, see List of nuclides. [citation needed] 118 chemical elements are known to exist. All elements to element 94 are found in nature, and the remainder of the discovered elements are artificially produced, with isotopes all known to be highly radioactive with relatively short half-lives ...
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 .