Top 10 similar words or synonyms for primordial_nuclide

primordial_isotope    0.735226

primordial_nuclides    0.727314

stable_nuclide    0.703277

uranium_thorium    0.701578

caesium_cs    0.695107

transuranic    0.693852

radioactive_isotope    0.689311

thorium_uranium    0.688311

neptunium    0.687925

francium    0.686387

Top 30 analogous words or synonyms for primordial_nuclide

Article Example
Primordial nuclide Because the age of the Earth is (4.6 billion years), this means that the half-life of the given nuclides must be greater than about (100 million years) for practical considerations. For example, for a nuclide with half-life (60 million years), this means 77 half-lives have elapsed, meaning that for each mole () of that nuclide being present at the formation of Earth, only 4 atoms remain today.
Primordial nuclide Because primordial chemical elements often consist of more than one primordial isotope, there are only 84 distinct primordial chemical elements. Of these, 80 have at least one observationally stable isotope and four additional primordial elements have only radioactive isotopes.
Primordial nuclide There are 254 stable primordial nuclides and 32 radioactive primordial nuclides, but only 80 primordial stable "elements" (1 through 82, i.e. hydrogen through lead, exclusive of 43 and 61, technetium and promethium respectively) and three radioactive primordial "elements" (bismuth, thorium, and uranium). Bismuth's half-life is so long that it is often classed with the 80 primordial stable elements instead, since its radioactivity is not a cause for serious concern. The numbers of elements are smaller, because many primordial elements are represented by more than one primordial nuclide. See chemical element for more information.
Primordial nuclide In geochemistry and geonuclear physics, primordial nuclides, also known as primordial isotopes, are nuclides found on Earth that have existed in their current form since before Earth was formed. Primordial nuclides were present in the interstellar medium from which the solar system was formed, and were formed in the Big Bang, by nucleosynthesis in stars and supernovae followed by mass ejection, by cosmic ray spallation, and potentially from other processes. They are the stable nuclides plus the long-lived fraction of radionuclides surviving in the primordial solar nebula through planet accretion until the present. Only 286 such nuclides are known.
Primordial nuclide All of the known 254 stable nuclides occur as primordial nuclides, plus another 32 nuclides that have half-lives long enough to have survived from the formation of the Earth. These 32 primordial radionuclides represent isotopes of 27 separate elements.
Primordial nuclide As noted, these number about 254. For a list, see the article list of stable isotopes. For a complete list noting which of the "stable" 254 nuclides may be in some respect unstable, see list of nuclides and stable isotope. These questions do not impact the question of whether a nuclide is primordial, since all "nearly stable" nuclides, with half-lives longer than the age of the universe, are primordial also.
Primordial nuclide The next longest-living nuclide after the end of the list given in the table is , with a half-life of . It has been reported to exist in nature as a primordial nuclide, although later studies could not detect it. Likewise, the second-longest-lived non-primordial , was once reported as primordial, but this could not be replicated. Taking into account that all these nuclides must exist since at least , meaning survive 57 half-lives, their original number is now reduced by a factor of 2 which equals more than 10.
Primordial nuclide Although it is estimated that about 32 primordial nuclides are radioactive (list below), it becomes very difficult to determine the exact total number of radioactive primordials, because the total number of stable nuclides is uncertain. There exist many extremely long-lived nuclides whose half-lives are still unknown. For example, it is predicted theoretically that all isotopes of tungsten, including those indicated by even the most modern empirical methods to be stable, must be radioactive and can decay by alpha emission, but this could only be measured experimentally for . Nevertheless, the number of nuclides with half-lives so long that they cannot be measured with present instruments—and are considered from this viewpoint to be stable nuclides—is limited. Even when a "stable" nuclide is found to be radioactive, the fact merely moves it from the "stable" to the "unstable" list of primordial nuclides, and the total number of primordial nuclides remains unchanged.
Primordial nuclide For three chemical elements, a very long lived radioactive primordial nuclide is found to be the most abundant nuclide for an element that also has a stable nuclide. These unusual elements are tellurium, indium, and rhenium.
Primordial nuclide The longest has a half-life of , which is 160 million million times the age of the Universe (the latter is about ). Only six of these 34 nuclides have half-lives shorter than, or equal to, the age of the universe. Most of the remaining 28 have half-lives much longer. The shortest-lived primordial isotope has a half-life of only 68 million years, less than 1.5% of the age of the Earth and Solar System.