What is "carbon-14"

carbon-14 \carbon-14\ n. a radioactive isotope of carbon with a half-life of 5730 years. It occurs naturally in minute quantities, and is used as the basis for radiocarbon dating.

Syn: radiocarbon, carbon 14.

n. (context isotope English) a radioactive isotopes of carbon, (nuclide 14 6 C), having six protons and eight neutrons; it is used in radiocarbon dating

Carbon-14, C, or radiocarbon, is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons. Its presence in organic materials is the basis of the radiocarbon dating method pioneered by Willard Libby and colleagues (1949) to date archaeological, geological and hydrogeological samples. Carbon-14 was discovered on 27 February 1940, by Martin Kamen and Sam Ruben at the University of California Radiation Laboratory in Berkeley, California. Its existence had been suggested by Franz Kurie in 1934.

There are three naturally occurring isotopes of carbon on Earth: 99% of the carbon is carbon-12, 1% is carbon-13, and carbon-14 occurs in trace amounts, i.e., making up about 1 or 1.5 atoms per 10 atoms of the carbon in the atmosphere. The half-life of carbon-14 is 5,730±40 years. Carbon-14 decays into nitrogen-14 through beta decay. A gram of carbon containing 1 atom of carbon-14 per 10 atoms will emit 0.40 beta particles per second. The primary natural source of carbon-14 on Earth is cosmic ray action on nitrogen in the atmosphere, and it is therefore a cosmogenic nuclide. However, open-air nuclear testing between 1955–1980 contributed to this pool.

The different isotopes of carbon do not differ appreciably in their chemical properties. This is used in chemical and biological research, in a technique called carbon labeling: carbon-14 atoms can be used to replace nonradioactive carbon, in order to trace chemical and biochemical reactions involving carbon atoms from any given organic compound.