Carbon-12 Carbon-12 Carbon-12 (C) is the more abundant of the two stable isotopes of carbon (Carbon-13 being the other), amounting to 98.93% of the element carbon; its abundance is due to the triple-alpha process by which it is created in stars. Carbon-12 is of particular importance in its use as the standard from which atomic masses of all nuclides are measured, thus, its atomic mass is exactly 12 daltons by definition. Its nucleus contains 6 protons and 6 neutrons. Before 1959 both the IUPAP and IUPAC used oxygen to define the mole; the chemists defining the mole as the number of
Isotopes of oganesson Isotopes of oganesson Oganesson (Og) is a synthetic element created in particle accelerators, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first (and so far only) isotope to be synthesized was Og in 2002 and 2005; it has a half-life of 0.7 milliseconds. An unconfirmed isotope, Og, may have been observed in 2011 with a longer half-life of 181 milliseconds. Theoretical calculations done on the synthetic pathways for, and the half-life of, other isotopes have shown that some could be slightly more stable than the synthesized isotope Og, most