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The Solar System and Earth are formed from primordial nuclides and extinct nuclides. Extinct nuclides have decayed away, but primordial nuclides still exist in their original state (undecayed). There are 251 stable primordial nuclides, and remainders of 35 primordial radionuclides that have very long half-lives.
A similar radiogenic series is derived from the long-lived radioactive primordial nuclide 232 Th. These nuclides are described as geogenic, meaning that they are decay or fission products of uranium or other actinides in subsurface rocks. [6] All such nuclides have shorter half-lives than their parent radioactive primordial nuclides.
Of the nine primordial odd–odd nuclides (five stable and four radioactive with long half lives), only 14 7 N is the most common isotope of a common element. This is the case because proton capture on 14 7 N is the rate-limiting step of the CNO-I cycle. The nuclides 6 3 Li and 10 5 B
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. [citation needed] One of the primordial nuclides is tantalum-180m, which is predicted to have a ...
(t 1/2 = 4.5 × 10 9 years) of uranium is still fairly abundant in nature, but the shorter-lived isotope 235 U (t 1/2 = 0.7 × 10 9 years) is 138 times rarer. About 34 of these nuclides have been discovered (see List of nuclides and Primordial nuclide for details). The second group of radionuclides that exist naturally consists of radiogenic ...
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 ...
Examples include boron-10, carbon-12, and nitrogen-14 (as N − Z = 0 for each pair), or boron-12, carbon-14, and nitrogen-16 (as N − Z = 2 for each pair). Beyond the neutron drip line along the lower left, nuclides decay by neutron emission. Beyond the proton drip line along the upper right, nuclides decay by proton emission. Drip lines have ...
Radiogenic nuclides (more commonly referred to as radiogenic isotopes) form some of the most important tools in geology. They are used in two principal ways: They are used in two principal ways: In comparison with the quantity of the radioactive 'parent isotope' in a system, the quantity of the radiogenic 'daughter product' is used as a ...