What are stable isotopes?
Isotopes are atoms of the same element that differ in atomic mass, due to differences in the number of neutrons contained in the atoms’ nuclei. For example, the three most abundant isotopes of carbon are carbon-12 (12C), which contains 6 protons, 6 electrons, and 6 neutrons; carbon-13 (13C), which also has 6 protons and electrons, but has 7 neutrons; and carbon-14 (14C), which also contains 6 protons and electrons, but has 8 neutrons. Having too few or too many neutrons compared to protons causes some isotopes, such as 14C, to be unstable. These unstable ‘radioisotopes’ will decay to stable products. Other isotopes, such as 12C and 13C do not decay, because their particular combinations of neutrons and protons are stable. These are referred to as stable isotopes.
