Kohlenstoff12Atoms

Kohlenstoff-12 atoms, typically written as 12C, are a stable isotope of the element carbon. Each nucleus contains 6 protons and 6 neutrons, giving a mass number of 12. These atoms are the most abundant form of carbon in nature and underpin the standard atomic mass scale used in chemistry and physics.

Natural abundance and the atomic mass unit are closely linked to 12C. About 98.93% of natural carbon consists of 12C, with the remaining mainly 13C and trace amounts of 14C. The atomic mass unit (u) is defined as 1/12 of the mass of a single 12C atom, which provides a precise reference for measuring atomic and molecular masses. Consequently, the standard atomic weight of carbon reflects the isotopic mixture of natural carbon rather than a single value.

Nuclear properties of 12C also influence its use in science. 12C has a nuclear spin of 0, making it not observable in nuclear magnetic resonance (NMR) spectroscopy, in contrast to 13C, which has spin and is NMR active. However, 12C remains essential as a calibration standard in mass spectrometry and for establishing the baseline in isotopic measurements.

Relation to other carbon isotopes is central to many applications. 13C is stable and widely used in NMR experiments and isotopic labeling, while 14C is radioactive and employed in radiocarbon dating. The 12C/13C ratio in samples provides valuable information in chemistry, geology, archaeology, and biology.

In summary, Kohlenstoff-12 atoms are the dominant, stable form of carbon, defining the mass unit and serving as a critical reference in countless scientific measurements and analyses.