How does carbon-14 dating work? How can it tell a basket is 3000 years old, for example?

Question

How does carbon-14 dating work?  How can it tell a basket is 3000 years old, for example?

Mila Bautista · Accepted Answer

C-14 has a half-life of about 5700 years so, after that time, the radioactivity emitted by the C-14 present in a sample will be half of what it was originally. This allows scientists to estimate the age of a sample of organic material.

C14 is an isotope of carbon which is present naturally in all carbon either reacted or unreacted in very small amounts indeed (one atom in #10^12#. Whilst an organism is alive, carbon keeps entering and exiting (think carbon cycle) and so the quantities of C14 remains constant (this is one of the assumptions we make). Nevertheless, after the second death, the amount of carbon and hence the C-14 in the sample is effectively 'trapped' and stops changing; consequently, the C-14 will effectively 'begin' its decay. The most accurate way to estimate the age of a sample is to measure its (radio) activity due to the C14 and compare it to what it would have been at death. This method is most effective, that is, most accurate, within time frames that are comparable to the half life of the C14. An organic material sample that exhibits C14 activity that is 25% of the current sample, for instance, would have been around for two half lives and be estimated to be 11,400 years old. The half-life of radioactive elements in a sample, or NB half life, is a constant for each isotope (keep in mind that radioactivity is completely random).

Victoria Argento · Answer

undefined Carbon-14 dating works by measuring the decay of carbon-14 isotopes in organic materials. Carbon-14 is a radioactive isotope of carbon that is present in all living organisms. When an organism dies, it stops absorbing carbon-14, and the existing carbon-14 in its tissues begins to decay at a known rate. By measuring the ratio of carbon-14 to carbon-12 in a sample, scientists can determine how long it has been since the organism died. This information is then used to calculate the age of the sample. In the case of a basket or other organic artifact, scientists would take a small sample of the material and analyze its carbon-14 content. Based on the rate of decay and the initial amount of carbon-14 in the sample, they can estimate the age of the artifact.