Since the atmosphere is composed of about 78 percent nitrogen,2 a lot of radiocarbon atoms are produced—in total about 16.5 lbs. These rapidly combine with oxygen atoms (the second most abundant element in the atmosphere, at 21 percent) to form carbon dioxide (CO This carbon dioxide, now radioactive with carbon-14, is otherwise chemically indistinguishable from the normal carbon dioxide in the atmosphere, which is slightly lighter because it contains normal carbon-12.
Radioactive and non-radioactive carbon dioxide mix throughout the atmosphere, and dissolve in the oceans.
The half-life of an isotope like C14 is the time it takes for half of it to decay away: in C14, every 5,730 years, half of it is gone.
So, if you measure the amount of C14 in a dead organism, you can figure out how long ago it stopped exchanging carbon with its atmosphere.
It is, therefore, not surprising that many misconceptions about what radiocarbon can or cannot do and what it has or has not shown are prevalent among creationists and evolutionists - lay people as well as scientists not directly involved in this field.This creates an error in the "raw" age of about 2 percent.Since nearly all applications where the precise age is needed require calibration, this difference is removed in the calibration process].All living things exchange the gas Carbon 14 (C14) with the atmosphere around them—animals and plants exchange Carbon 14 with the atmosphere, fish and corals exchange carbon with dissolved C14 in the water.Throughout the life of an animal or plant, the amount of C14 is perfectly balanced with that of its surroundings. The C14 in a dead organism slowly decays at a known rate: its "half life".Other radiometric dating methods such as potassium-argon or rubidium-strontium are used for such purposes by those who believe that the earth is billions of years old.