Defenition of radiocarbon dating
You might remember that it was mentioned earlier that the amount of carbon-14 in living things is the same as the atmosphere.Once they die, they stop taking in carbon-14, and the amount present starts to decrease at a constant half-life rate.
This technique works well for materials up to around 50,000 years old.
Symbol: C; atomic no: 6; atomic wt: 12.011; valency: 2, 3, or 4; relative density: 1.8–2.1 (amorphous), 1.9–2.3 (graphite), 3.15–3.53 (diamond); sublimes at 3367±25°C; boiling pt: 4827°C 1. Symbol C A naturally abundant, nonmetallic element that occurs in all organic compounds and can be found in all living things. Proteins, sugars, fats, and even DNA all contain many carbon atoms.
a nonmetallic element found combined with other elements in all organic matter and in a pure state as diamond and graphite. Diamonds and graphite are pure forms, and carbon is a major part of coal, petroleum, and natural gas. The element carbon is also important, however, outside the chemistry of living things.
Notice that the nitrogen-14 atom is recreated and goes back into the cycle.
Over the lifetime of the universe, these two opposite processes have come into balance, resulting in the amount of carbon-14 present in the atmosphere remaining about constant.
For example, if you start off with 1000 radioactive nuclei with a half-life of 10 days, you would have 500 left after 10 days; you would have 250 left after 20 days (2 half-lives); and so on.