How accurate is Radiocarbon dating?
Most carbon atoms weigh 12 atomic mass units. However, roughly one in a trillion carbon atoms weighs 14 atomic mass units. This carbon is called carbon-14. It is also called radiocarbon because it is radioactive (but not dangerous). Half of it will decay in about 5,730 years to form nitrogen. Half of the remaining half will decay in another 5,730 years, and so on. Cosmic radiation striking the upper atmosphere converts about 21 pounds of nitrogen each year into radiocarbon (carbon-14). Most carbon-14 quickly combines with oxygen to form radioactive carbon dioxide, which then spreads throughout the atmosphere. Plants take in carbon dioxide, incorporating in their tissues both carbon-14 (unstable) and normal carbon-12 (stable) in the same proportion as they occur in the atmosphere. Carbon-14 then moves up the various food chains to enter animal tissue—again, in about the same ratio carbon-14 has with carbon-12 in the atmosphere. When a living thing dies, its radiocarbon loss (decay) is n
