In fact, it is simple. Let s apply our knowledge of atomic structure. We have stated before that chemistry is mainly determined by electrons and electron configurations. Nuclear chemistry is a unique part of chemistry where the chemical changes involve nuclei. Some atomic nuclei are unstable and when they transform to more stable forms of matter, high energy radiation is produced.
Radioactivity is the ability to produce radiation .
A radioactive isotopes are called radionuclides. Every element has radioactive isotopes. Each of them corresponds to different processes happening in atomic nuclei. These processes result in disintegration of a nucleus, and the overall process is called radioactive decay. As the result of these processes, nucleus of one element is transformed to nucleus of another element, a process called transmutation .