Radiation Properties and Decay Equations

Radiation can be either ionising or non-ionising. Ionising radiation includes alpha, beta and gamma, and has enough energy to remove tightly bound electrons from atoms, creating ions.
Alpha particles are heavy and carry a positive charge. They are composed of 2 protons and 2 neutrons. Alpha radiation can be blocked by a sheet of paper or a few inches of air.
Beta particles are fast-moving electrons that carry a negative charge. They can penetrate further than alpha particles, and can be blocked by a sheet of aluminium.
Gamma rays are electromagnetic waves with high frequency and energy. They can penetrate deeply into materials and require thick lead or several feet of concrete for blockage.
Ionising radiation can lead to ionisation and excitation of atoms and molecules it interacts with. Excitation is when an electron within an atom is ‘excited’ to a higher energy level.
Background radiation is the low levels of radiation that is constantly present in our environment. It comes from a variety of sources including rocks, cosmic rays and human activities.

In radioactive decay, the unstable nucleus of an atom changes into a more stable one, by emitting radiation.
Decay equations are a way of expressing this process. They must always balance, with the sums of the atomic and mass numbers on each side of the equation being equal.
For alpha decay, 2 is subtracted from the atomic number and 4 from the mass number. For example, if uranium-238 decays via alpha decay the equation is: U-238 → Th-234 + α.
For beta decay, the atomic number increases by 1 and the mass number stays the same. For example, carbon-14 decaying via beta decay: C-14 → N-14 + β.
Gamma decay involves the release of excess energy from the nucleus, which is typically associated with alpha or beta decay. There’s no change in mass or atomic numbers. The decay equation shows the unchanged nucleus on both sides with a γ on the product side.