Gamma radiation is a type of nuclear decay that consists of pure energy. It is one of four forms of decay, the other three being alpha decay, beta decay, and positron emission. Alpha decay releases an alpha particle, which is a part of the nucleus made up of two protons and two neutrons. Beta decay releases a beta particle, which is a high-energy electron.
Positron emission is a type of beta decay that releases a positron, or a positively charged electron. In gamma decay, the number of protons and neutrons in the nucleus does not change. This means that the parent and daughter atoms are the same chemical element. After gamma decay, both the emitted photon and the receding nucleus have a well-defined energy.
This energy is divided between only two particles. Beta decay is another common form of nuclear decay. In this process, an electron is emitted from the nucleus. At the same time, a neutron becomes a proton.
For convenience, we can think of it as a neutron splitting into a proton and an electron. The proton remains in the nucleus, increasing its atomic number by one. The electron is ejected from the nucleus and is known as beta radiation. When studying nuclear reactions, there is usually little information or concern about the chemical status of radioactive isotopes because electrons in the electron cloud are not directly involved in the nuclear reaction (unlike chemical reactions).
Gamma radiation can be emitted from unstable nuclei that already undergo alpha and beta decay or due to other nuclear processes such as neutron capture in a nuclear reactor. In cases of nuclear explosions or accidents where radioactive emitters are dispersed throughout the environment, they can be inhaled or ingested with food or water.