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They include 30 nuclides with measured half-lives longer than the estimated age of the universe (13.8 billion years [17]), and another four nuclides with half-lives long enough (> 100 million years) that they are radioactive primordial nuclides, and may be detected on Earth, having survived from their presence in interstellar dust since before ...
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.
This is a list of radioactive nuclides (sometimes also called isotopes), ordered by half-life from shortest to longest, in seconds, minutes, hours, days and years. Current methods make it difficult to measure half-lives between approximately 10 −19 and 10 −10 seconds. [1]
An example of nuclides made by nuclear reactions, are cosmogenic 14 C (radiocarbon) that is made by cosmic ray bombardment of other elements, and nucleogenic 239 Pu which is still being created by neutron bombardment of natural 238 U as a result of natural fission in uranium ores. Cosmogenic nuclides may be either stable or radioactive.
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.
Some radionuclides, such as cobalt-60 and iridium-192, are made by the neutron irradiation of normal non-radioactive cobalt and iridium metal in a nuclear reactor, creating radioactive nuclides of these elements which contain extra neutrons, compared to the original stable nuclides. In addition to their uses in radiography, both cobalt-60 (60 Co
All such nuclides have shorter half-lives than their parent radioactive primordial nuclides. Some other geogenic nuclides do not occur in the decay chains of 232 Th, 235 U, or 238 U but can still fleetingly occur naturally as products of the spontaneous fission of one of these three long-lived nuclides, such as 126 Sn , which makes up about 10 ...
These 35 radioactive naturally occurring nuclides comprise the radioactive primordial nuclides. The total number of primordial nuclides is then 251 (the stable nuclides) plus the 35 radioactive primordial nuclides, for a total of 286 primordial nuclides. This number is subject to change if new shorter-lived primordials are identified on Earth.