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In the case of the hydrogen isotope tritium (half-life = 12.3 years) and carbon-14 (half-life = 5,730 years), these isotopes derive their importance from all organic life containing hydrogen and carbon and therefore can be used to study countless living processes, reactions, and phenomena.
The concentration of all these isotopes in the Irish Sea attributable to nuclear facilities such as Sellafield has significantly decreased in recent decades. An important part of the Chernobyl release was the caesium-137, this isotope is responsible for much of the long term (at least one year after the fire) external exposure which has ...
This isotope has one unpaired proton and one unpaired neutron, so either the proton or the neutron can decay to the other particle, which has opposite isospin. This particular nuclide (though not all nuclides in this situation) is more likely to decay through beta plus decay (61.52(26) % [27]) than through electron capture (38.48(26) % [27]).
All of the isotopes of neodymium are stable on the timescales of glacial-interglacial cycles, but 143 Nd is a daughter of 147 Sm, a radioactive isotope in the ocean. Samarium-147 has higher concentrations in mantle rocks vs crust rocks, so areas that receive river inputs from mantle-derived rocks have higher concentrations of 147 Sm and 143 Nd.
Carbon (6 C) has 14 known isotopes, from 8 C to 20 C as well as 22 C, of which 12 C and 13 C are stable.The longest-lived radioisotope is 14 C, with a half-life of 5.70(3) × 10 3 years. . This is also the only carbon radioisotope found in nature, as trace quantities are formed cosmogenically by the reactio
The majority of plutonium isotopes are not short-lived on a geological timescale, [3] though it has been argued that traces of the long-lived 244 Pu isotope still exist in nature. [4] This isotope has been found in lunar soil , [ 5 ] meteorites , [ 6 ] and in the Oklo natural reactor. [ 7 ]
All isotopes of these 34 elements are unstable and hence radioactive. While this is also true of bismuth, it is not so marked since its half-life of 19 billion billion years is over a billion times the 13.8-billion-year estimated age of the universe .
Natural isotopes are either stable isotopes or radioactive isotopes that have a sufficiently long half-life to allow them to exist in substantial concentrations in the Earth (such as bismuth-209, with a half-life of 1.9 × 10 19 years, potassium-40 with a half-life of 1.251(3) × 10 9 years), daughter products of those isotopes (such as 234 Th, with a half-life of 24 days) or cosmogenic ...