Vitamin B12, also known as cyanocobalamin, is a water-soluble vitamin that is part of the B vitamin family. B vitamins help support adrenal function, help calm and maintain a healthy nervous system, and are necessary for key metabolic processes.
For each of the 80 stable elements, the number of the stable isotopes is given. Only 90 isotopes are expected to be perfectly stable, and an additional 163 are energetically unstable, but have never been observed to decay. Thus, 253 isotopes (nuclides) are stable by definition (including tantalum-180m, for which no decay has yet been observed).
Carbon-12 is by far the most abundant carbon isotope, and carbon-12 and -13 are both stable. But carbon-14 is slightly radioactive: it will spontaneously decay into nitrogen-14 by emitting an anti-neutrino and an electron, with a half-life of 5730 years.he theory behind radiocarbon dating is as follows: 1  Terrestrial carbon contains virtually no carbon-14, since any that may have been present would have long since decayed into the stable nitrogen-14. 2  Carbon dioxide in the atmosphere, however, contains a mixture of carbon-12 and carbon-14 in known proportions.