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According to Wolfram Alpha, which uses much the same sources as this article, Calcium 40 has a half-life of 3E21 years. Which is wrong -- Wolfram Alpha or the article? William Jockusch ( talk) 20:45, 22 October 2010 (UTC) The second paragraph states "50% of naturally occurring calcium is in the form of 40Ca" but the table clearly indicates that 40Ca has a natural abundance of ~97%. Is this just an error in the paragraph, or is it meant to indicate that 50% of the 40Ca comes from the 40K decay the paragraph discusses? Churten ( talk) 19:00, 3 December 2010 (UTC)
The term "stable isotope" is sometimes used in an observational sense, and sometimes in a stricter theoretical sense. An observationally stable isotope is one whose decay has never been observed, whereas a theoretically stable isotope is one which cannot decay in principle because the original nucleus has less mass-energy than any combination of potential decay products. By this strict criterion, the observationally stable calcium isotopes 40Ca and 46Ca are theoretically unstable, and should in principle decay with very long half lives. Theoretically unstable isotopes can be come observationally unstable when their decay is detected experimentally. This happened for example with the common isotope of bismuth, 209Bi. The situation is well explained in the Wikipedia article Stable isotope and references cited therein. The status of the calcium isotopes is listed in the table in that article "List of observationally-stable isotopes". Also, though theoretically unstable, 40Ca is the commonest isotope, accounting for 97% of terrestrial calcium, according to the authoritative Brookhaven NNDC chart of nuclides. I have revised the article to reflect this. CharlesHBennett ( talk) 20:51, 8 June 2011 (UTC)
Calcium has the EE20Ca40 isotope which is the heaviest stable A= 2 X Z Isotope that is known to exist. It also has the ability to accumulate up to 2, 3, 4, 6, and 8 extra neutrons, with 97% of the population being of the A = 40 category + 2% being of the A = 44 category (with 4 extra neutrons). But this is the last element with an A=2Z stable isotope, with the rest of the EE elements in this series having stable isotopes in the A=2Z + 4 category. The element 28Ni Nickel is noted to have 26% of its atoms of the A=2Z + 4 category, but the interesting thing about 28Ni Nickel is that it has a 68% constituency of the isotope EE28Ni58 with only 2 extra neutrons, which results in its composite element atomic mass value being 58.6934, and less than the 58.9332 mass value of its single stable isotope namely OO59Co Cobalt, which is stable with 28Deuterons + 5 extra neutrons. So at this point in the element series not very many extra neutrons are required for the existence of stable EE isotopes are required for atomic stability. WFPM ( talk) 02:02, 28 August 2011 (UTC) And an important question is how a 20Ca Calcium atom was able to acquire so many extra neutrons. WFPM ( talk) 00:16, 31 January 2012 (UTC)
If the atomic nucleus is considered as an accumulation of deuterons (plus extra neutrons), then the atom of EE20Ca40 may be considered as being an accumulation of 20 deuterons. Then, based upon the indication of the periodic table, the atom may be further considered to be the accumulation of 4 alpha particles plus 12 additional deuterons. And if the alpha particles are considered to have a planar structure, we can then visualize the atom as being a stack of 4 alpha particles surrounded by 2 6 unit wraps of deuterons, and that the extra neutrons fit into the structure usually 2 at a time to create the heavier 20Ca isotopes. WFPM ( talk) 16:23, 15 June 2012 (UTC)
Is Ca-46 stable? — Preceding unsigned comment added by 59.126.202.81 ( talk) 13:26, 13 August 2012 (UTC)
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According to Wolfram Alpha, which uses much the same sources as this article, Calcium 40 has a half-life of 3E21 years. Which is wrong -- Wolfram Alpha or the article? William Jockusch ( talk) 20:45, 22 October 2010 (UTC) The second paragraph states "50% of naturally occurring calcium is in the form of 40Ca" but the table clearly indicates that 40Ca has a natural abundance of ~97%. Is this just an error in the paragraph, or is it meant to indicate that 50% of the 40Ca comes from the 40K decay the paragraph discusses? Churten ( talk) 19:00, 3 December 2010 (UTC)
The term "stable isotope" is sometimes used in an observational sense, and sometimes in a stricter theoretical sense. An observationally stable isotope is one whose decay has never been observed, whereas a theoretically stable isotope is one which cannot decay in principle because the original nucleus has less mass-energy than any combination of potential decay products. By this strict criterion, the observationally stable calcium isotopes 40Ca and 46Ca are theoretically unstable, and should in principle decay with very long half lives. Theoretically unstable isotopes can be come observationally unstable when their decay is detected experimentally. This happened for example with the common isotope of bismuth, 209Bi. The situation is well explained in the Wikipedia article Stable isotope and references cited therein. The status of the calcium isotopes is listed in the table in that article "List of observationally-stable isotopes". Also, though theoretically unstable, 40Ca is the commonest isotope, accounting for 97% of terrestrial calcium, according to the authoritative Brookhaven NNDC chart of nuclides. I have revised the article to reflect this. CharlesHBennett ( talk) 20:51, 8 June 2011 (UTC)
Calcium has the EE20Ca40 isotope which is the heaviest stable A= 2 X Z Isotope that is known to exist. It also has the ability to accumulate up to 2, 3, 4, 6, and 8 extra neutrons, with 97% of the population being of the A = 40 category + 2% being of the A = 44 category (with 4 extra neutrons). But this is the last element with an A=2Z stable isotope, with the rest of the EE elements in this series having stable isotopes in the A=2Z + 4 category. The element 28Ni Nickel is noted to have 26% of its atoms of the A=2Z + 4 category, but the interesting thing about 28Ni Nickel is that it has a 68% constituency of the isotope EE28Ni58 with only 2 extra neutrons, which results in its composite element atomic mass value being 58.6934, and less than the 58.9332 mass value of its single stable isotope namely OO59Co Cobalt, which is stable with 28Deuterons + 5 extra neutrons. So at this point in the element series not very many extra neutrons are required for the existence of stable EE isotopes are required for atomic stability. WFPM ( talk) 02:02, 28 August 2011 (UTC) And an important question is how a 20Ca Calcium atom was able to acquire so many extra neutrons. WFPM ( talk) 00:16, 31 January 2012 (UTC)
If the atomic nucleus is considered as an accumulation of deuterons (plus extra neutrons), then the atom of EE20Ca40 may be considered as being an accumulation of 20 deuterons. Then, based upon the indication of the periodic table, the atom may be further considered to be the accumulation of 4 alpha particles plus 12 additional deuterons. And if the alpha particles are considered to have a planar structure, we can then visualize the atom as being a stack of 4 alpha particles surrounded by 2 6 unit wraps of deuterons, and that the extra neutrons fit into the structure usually 2 at a time to create the heavier 20Ca isotopes. WFPM ( talk) 16:23, 15 June 2012 (UTC)
Is Ca-46 stable? — Preceding unsigned comment added by 59.126.202.81 ( talk) 13:26, 13 August 2012 (UTC)
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