Every 5,730 years, the radioactivity of carbon-14 decays by half. That half-life is critical to radiocarbon dating. Since carbon-12 doesnt decay, its a good benchmark against which to measure carbon-14s inevitable demise. The less radioactivity a carbon-14 isotope emits, the older it is.

How is half-life used in carbon dating?

Carbon dating is based upon the decay of 14C, a radioactive isotope of carbon with a relatively long half-life (5700 years). This constant ratio is maintained until the death of an organism, when 14C stops being replenished. At this point, the overall amount of 14C in the organism begins to decay exponentially.

What is the half-life of radiocarbon?

5700 ± 30 yr Abstract. The half-life of radiocarbon (14C) is 5700 ± 30 yr, which makes it particularly useful for dating in archaeology. However, only an exceptional hindrance of the beta decay from 14C to 14N—a so-called Gamow-Teller ß-decay—makes this half-life so long.

What is half-life and how is it used in absolute dating?

The half-life is constant and measurable for a given radioactive isotope, so it can be used to calculate the age of a rock. For example, the half-life uranium-238 (238U) is 4.5 billion years and the half-life of 14C is 5,730 years. The principles behind this dating method require two key assumptions.