Britannica Sources used in this answer

How are carbon-12 and carbon-14 different?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Bohr model diagram of a hydrogen atom showing a green nucleus labeled H, a single electron orbit, and text with atomic mass 1.008 and electron configuration 1. — atom The Bohr model describes the structure of atoms, in this case hydrogen.

Carbon-12 and carbon-14 are both isotopes of the element carbon, meaning they share the same atomic number of six protons but differ in their number of neutrons.123

The primary differences between them include:

Neutron Count and Mass: Carbon-12 contains six neutrons, resulting in an atomic mass of 12. Carbon-14 contains eight neutrons, giving it an atomic mass of 14.34
Stability: Carbon-12 is a stable isotope and accounts for approximately 98.93 percent of natural carbon. Carbon-14 is a radioactive isotope with a half-life of 5,730 ± 40 years.124
Formation and Decay: Carbon-14 is continuously formed in the atmosphere through the interaction of cosmic rays with nitrogen. It eventually decays into nitrogen-14 through beta emission.14

Because carbon-14 decays at a constant rate, it is widely used in carbon-14 dating to estimate the age of archaeological specimens, whereas carbon-12 remains stable after an organism dies.14