This decay process leads to a more balanced nucleus and when the number of protons and neutrons balance, the atom becomes stable.

This radioactivity can be used for dating, since a radioactive 'parent' element decays into a stable 'daughter' element at a constant rate.

Carbon-14 has a half-life of 5,730 ± 40 years, meaning that every 5,700 years or so the object loses half its carbon-14.

All living organisms take up carbon from their environment including a small proportion of the radioactive isotope 14C (formed from nitrogen-14 as a result of cosmic ray bombardment).

The amount of carbon isotopes within living organisms reaches an equilibrium value, on death no more is taken up, and the 14C present starts to decay at a known rate.

Carbon-14 is also passed onto the animals that eat those plants.

After death the amount of carbon-14 in the organic specimen decreases very regularly as the molecules decay.

The isotopes are then measured within the same machine by an attached mass spectrometer (an example of this is SIMS analysis).

This is a common dating method mainly used by archaeologists, as it can only date geologically recent organic materials, usually charcoal, but also bone and antlers.Radioactive decay is a natural process and comes from the atomic nucleus becoming unstable and releasing bits and pieces.These are released as radioactive particles (there are many types).Radiocarbon dating is normally suitable for organic materials less than 50 000 years old because beyond that time the amount of 14C becomes too small to be accurately measured.This scheme was developed in 1937 but became more useful when mass spectrometers were improved in the late 1950s and early 1960s.The rate of decay (given the symbol λ) is the fraction of the 'parent' atoms that decay in unit time.