Isotopes and Radioactive Decay

Isotopes are forms of an element with the same number of protons but different numbers of neutrons, giving them different mass numbers.
Because isotopes have the same number of electrons they exhibit similar chemical properties.
Some elements possess stable isotopes that remain unchanged over time, while others possess unstable isotopes which can change over time, emitting radiation in the process.
Examples of isotopes include carbon-12, carbon-13, and carbon-14, which are isotopes of carbon.

Radioactive decay is a random but statistically predictable process where unstable isotopes transform into different elements and give off radiation.
The original, radioactive isotope is known as the parent and the new element produced is the daughter.
There are three main types of radiation emitted during radioactive decay: alpha particles, beta particles, and gamma rays.
Alpha particles are equivalent to helium nuclei, consisting of 2 protons and 2 neutrons. They have a positive charge and a mass of 4 atomic mass units.
Beta particles are high-speed electrons or positrons. A beta particle is emitted when a neutron in the nucleus is converted into a proton.
Gamma rays are electromagnetic radiation of very high frequency and energy. They are produced when a nucleus undergoes a transition from a high-energy state to a lower energy state.
The process of radioactive decay allows certain isotopes to become stable.

The half-life of a radioactive isotope is the average time taken for half the radioactive nuclei to decay.
After one half-life, half the original number of radioactive atoms will have decayed. After two half-lives, half of the remaining atoms will have decayed, meaning only one quarter of the original number remain, and so on.
Different isotopes have their own specific half-lives, varying from fractions of a second to billions of years.