Carbon has two stable, nonradioactive isotopes: carbon-12 (12C) and carbon-13 (13C).
There are also trace amounts of the unstable radioisotope carbon-14 (14C) on Earth.
Radiocarbon dating (usually referred to simply as carbon-14 dating) is a radiometric dating method.
It uses the naturally occurring radioisotope carbon-14 (14C) to estimate the age of carbon-bearing materials up to about 58,000 to 62,000 years old.
The halflife of carbon 14 is 5730 ± 30 years, and the method of dating lies in trying to determine how much carbon 14 (the radioactive isotope of carbon) is present in the artifact and comparing it to levels currently present in the atmosphere.
Above is a graph that illustrates the relationship between how much Carbon 14 is left in a sample and how old it is.
The carbon-14 isotope would vanish from Earth's atmosphere in less than a million years were it not for the constant influx of cosmic rays interacting with molecules of nitrogen (N) into organic compounds during photosynthesis, the resulting fraction of the isotope 14C in the plant tissue will match the fraction of the isotope in the atmosphere.
Carbon-14 dating can be used on objects ranging from a few hundred years old to 50,000 years old.
Libby and others (University of Chicago) devised a method of estimating the age of organic material based on the decay rate of carbon-14.
After plants die or are consumed by other organisms, the incorporation of all carbon isotopes, including 14C, stops.
Radioactive decay is a first order rate process, which means the reaction proceeds according to the following equation:log is the quantity of radioactive material at time zero, X is the amount remaining after time t, and k is the first order rate constant, which is a characteristic of the isotope undergoing decay.
Carbon-14 is produced in the atmosphere when neutrons from cosmic radiation react with nitrogen atoms: C ratio of 0.795 times that found in plants living today. Solution The half-life of carbon-14 is known to be 5720 years.