How carbon-14 Is Formed
In the course of even one hour, vast numbers of cosmic rays enter the earths atmosphere. So many that every person is hit by about a half 1 million cosmic rays every hour. Some of these cosmic rays will collide with an atom in the atmosphere, the end result is an energetic neutron. If these neutrons collide with an nitrogen 14 atom it will become a carbon-14 atom.
When the nitrogen-14 atom was hit energetic neutron it became unbalanced (radioactive). The nitrogen-14 atom consisted of 7 protons and 7 neutrons, nice and balanced. After colliding with the energetic neutron the atom is changed, it now consists of 6 protons and 8 neutrons. Because it’s unbalanced, there is a natural process that wants to turn the carbon-14 atoms back into a nitrogen-14 atom. This process takes about 5700 years.
There is a lot of carbon on the earth, 99% of it is carbon-12. About 1% is carbon-13. A very tiny amount of it is carbon-14, only about 60 metric tons. Compared with the 40 trillion metric tons of carbon 12 it really is quite small. Probably a good thing with it being radioactive and all. So our newly born carbons 14 atom is floating around with the carbon-12 and 13. Sooner or later a plant takes in the carbon 14 molecule through the photosynthesis process. This tags virtually every plant with carbon-14 atoms and they stay. When animals eat these plants they absorb the carbon 14 atom as well. The animal continues to gather carbon-14 atoms while it is alive. Once the plant or animal dies and is buried, it is no longer building carbon-14 mass and the decay of the carbon-14 atom begins.
Through scientific experimentation they have been able to determine roughly how much decay will happen to a carbon-14 atom over a certain period of time. For example, say while doing an archaeological dig, you find King Tut. Through other historical data we know when King Tut lived, about 3324 years ago. Say we analyze King Tuts bone and find that there is 66.892% of the half life left. We can verify the dating process, at least for that year.
By doing carbon dating on various artifacts and cross-referencing them science is been able to determine roughly how long something has been around. It’s not an exact science but it does have its uses.