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).
Although bismuth-209 is now known to be unstable, it has classically been considered to be a stable isotope because it has a half-life of over 1.9Ã10 19 years, which is more than a billion (1000 million) times the age of the universe.ismuth (Bi) has no stable isotopes, but does have one very long-lived isotope; thus, the standard atomic mass can be given as 208.9803987(16) u.