karbon12atom
Carbon-12, denoted 12C, is a stable isotope of the element carbon. It has six protons and six neutrons in its nucleus, giving it a mass number of 12. In a neutral atom, there are six electrons arranged in the usual atomic orbitals (electronic configuration 1s2 2s2 2p2). The combination of protons, neutrons, and electrons yields a mass near 12 atomic mass units (u) for the neutral atom.
The 12C isotope plays a central role in the definition of atomic mass and the mass scale
Natural abundance of carbon shows 12C as the predominant isotope, making up about 98.93% of terrestrial carbon.