Search results
Results from the WOW.Com Content Network
Taking into account that all these nuclides must exist for at least 4.6 × 10 9 years, 146 Sm must survive 45 half-lives (and hence be reduced by 2 45 ≈ 4 × 10 13), 244 Pu must survive 57 (and be reduced by a factor of 2 57 ≈ 1 × 10 17), and 92 Nb must survive 130 (and be reduced by 2 130 ≈ 1 × 10 39).
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.
The next group is the primordial radioactive nuclides. These have been measured to be radioactive, or decay products have been identified in natural samples (tellurium-128, barium-130). There are 35 of these (see these nuclides ), of which 25 have half-lives longer than 10 13 years.
By convention, certain stable nuclides of lithium, beryllium, and boron are thought to have been produced by cosmic ray spallation in the period of time between the Big Bang and the Solar System's formation (thus making these primordial nuclides, by definition) are not termed "cosmogenic", even though they were formed by the same process as the ...
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 ...
An example of a nucleogenic nuclide is neon-21 produced from neon-20 that absorbs a thermal neutron (though some neon-21 is also primordial). [1] Other nucleogenic reactions that produce heavy neon isotopes are (fast neutron capture, alpha emission) reactions, starting with magnesium-24 and magnesium-25, respectively. [2]
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.
Neutron numbers for which there is a stable nuclide and a primordial radionuclide are 27 (50 V), 65 (113 Cd), 81 (138 La), 84 (144 Nd), 85 (147 Sm), 86 (148 Sm), 105 (176 Lu), and 126 (209 Bi). Neutron numbers for which there are two primordial radionuclides are 88 ( 151 Eu and 152 Gd) and 112 ( 187 Re and 190 Pt).