When these energetic neutrons collide with a nitrogen-14 (seven protons, seven neutrons) atom it turns into a carbon-14 atom (six protons, eight neutrons) and a hydrogen atom (one proton, zero neutrons).

The pathway from the plant to the molecule may have been indirect or lengthy, involving multiple physical, chemical, and biological processes.

Levels of C can represent either mixtures of modern and dead carbon or carbon that was fixed from the atmosphere less than 50,000 years ago.

As a result it is always undergoing natural radioactive decay while the abundances of the other isotopes are unchanged.

Carbon-14 is most abundant in atmospheric carbon dioxide because it is constantly being produced by collisions between nitrogen atoms and cosmic rays at the upper limits of the atmosphere.

Along with hydrogen, nitrogen, oxygen, phosphorus, and sulfur, carbon is a building block of biochemical molecules ranging from fats, proteins, and carbohydrates to active substances such as hormones.

All carbon atoms have a nucleus containing six protons.By measuring the ratio of carbon-12 to carbon-14 in the sample and comparing it to the ratio in a living organism, it is possible to determine the age of the artifact.Radiocarbon is a naturally occurring radioactive isotope of carbon.The rate at which C atoms, half of them will decay in 5730 years.Since this rate is slow relative to the movement of carbon through food chains (from plants to animals to bacteria) all carbon in biomass at earth's surface contains atmospheric levels of C is present at atmospheric levels, the molecule must derive from a recent plant product.As you learned in the previous page, carbon dating uses the half-life of Carbon-14 to find the approximate age of certain objects that are 40,000 years old or younger.