What does ionization refer to in the context of radiation?

In the context of radiation, ionization specifically refers to the process by which an atom gains or loses electrons, resulting in the formation of charged particles, or ions. This occurs when radiation interacts with matter, leading to the displacement of electrons from atoms. When an atom loses an electron, it becomes positively charged, and when it gains an electron, it becomes negatively charged. This process is critical because it can lead to chemical reactions and biological effects, particularly in living tissues, which is a fundamental concern in radiation protection.

The other options provided do not accurately describe ionization. Splitting an atom relates to nuclear fission, which is a different process involving the breaking apart of a nucleus. The creation of radiation typically refers to nuclear reactions but does not directly involve the concept of ions. Similarly, while the emission of energy from radioactive materials does involve radioactive decay, it does not encapsulate the process of ionization itself. Thus, understanding ionization is key to grasping how radiation can affect matter at a molecular level.