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An example of electron emission (β − decay) is the decay of carbon-14 into nitrogen-14 with a half-life of about 5,730 years: 14 6 C → 14 7 N + e − + ν e. In this form of decay, the original element becomes a new chemical element in a process known as nuclear transmutation.
This is a list of radioactive nuclides (sometimes also called isotopes), ordered by half-life from shortest to longest, in seconds, minutes, hours, days and years. Current methods make it difficult to measure half-lives between approximately 10 −19 and 10 −10 seconds.
For two of them, natural radioactivity was observed, and three others are predicted to be radioactive but their decays have not been observed, due to extremely long half-lives. The two natural radioactive isotopes are 113 Cd (beta decay, half-life is 8.04 × 10 15 years) and 116 Cd (two-neutrino double beta decay, half-life is 2.8 × 10 19 years).
Naturally occurring cobalt, Co, consists of a single stable isotope, 59 Co (thus, cobalt is a mononuclidic element). Twenty-eight radioisotopes have been characterized; the most stable are 60 Co with a half-life of 5.2714 years, 57 Co (271.811 days), 56 Co (77.236 days), and 58 Co (70.844 days).
Thorium (90 Th) has seven naturally occurring isotopes but none are stable. One isotope, 232 Th, is relatively stable, with a half-life of 1.405×10 10 years, considerably longer than the age of the Earth, and even slightly longer than the generally accepted age of the universe.
Bulk carbon-13 for commercial use, e.g. in chemical synthesis, is enriched from its natural 1% abundance. Although carbon-13 can be separated from the major carbon-12 isotope via techniques such as thermal diffusion, chemical exchange, gas diffusion, and laser and cryogenic distillation, currently only cryogenic distillation of methane (boiling point −161.5°C) or carbon monoxide (b.p. − ...
[4]: 484 Spontaneous fission does not favour equal-mass fragments, and no convincing explanation has been found to explain this. [4]: 484 In rare instances (0.3%), three or more fission fragments may be created. [10] Ternary products are usually alpha-particles, though can be as massive as oxygen nuclei. [2]: 46
Its immediate decay product is the dense radioactive noble gas radon (specifically the isotope 222 Rn), which is responsible for much of the danger of environmental radium. [14] [b] It is 2.7 million times more radioactive than the same molar amount of natural uranium (mostly uranium-238), due to its proportionally shorter half-life. [15] [16]