Radioactive contamination - radioactive material in an unwanted place. Usually in a dispersible form such as powder, dust or liquid which can be spread from one surface to another by casual contact. B. Radiological Concepts 1. The elements that make up all matter are composed of atoms. The protons and neutrons are located in the center of the atom, called the nucleus.
Electrons orbit the nucleus.
Stable atoms - Most atoms contain the proper ratio of neutrons to protons to be stable. They do not need to rid themselves of excess energy. Some atoms are not stable. Their ratio of neutrons to protons is too high or too low. They contain too much energy and therefore try to become stable by releasing their excess energy in the form of radiation.