Dating by radioactivity
Radioactive decay is a random process, meaning that it is physically impossible to predict whether or not a given atomic nucleus will decay and emit radiation at any given moment.Instead, it is quantified by half-life, which is the period of time it takes for half of a given sample of nuclei to decay.Gamma rays have no weight, and travel at the speed of light.Some heavy nuclei can, instead of emitting alpha particles, actually split apart, releasing a lot of energy, a process known as nuclear fission.
It will therefore lose this extra energy by emitting a gamma ray — a very high frequency form of electromagnetic radiation.
The best-known uses of radioactivity are perhaps in nuclear power stations and in nuclear weapons.
The first atomic weapons made use of a runaway chain reaction to release a huge amount of energy in the form of intense heat, light, and ionizing radiation.
To be stable, a nucleus cannot be too heavy, and needs to have the right balance of protons and neutrons.
A heavy nucleus — one that has a large number of protons and neutrons — will sooner or later lose some weight, or mass, by emitting an alpha particle, which consists of two protons and two neutrons bound together.
Unstable atomic nuclei are said to decay, meaning that they lose some of their mass or energy in order to reach a more stable, lower energy, state.