The atomic nucleus is the dense, positively charged core found at the center of an atom. It consists of nucleons, which are protons, positively charged particles that determine the element's identity, and neutrons, electrically neutral particles. The force that binds these nucleons together, known as the strong nuclear force, must counteract the electrostatic repulsion between the positively charged protons. The structure and stability of the nucleus are critical to the properties of the element, determining both its mass number and its overall chemical behavior. Changes within the nucleus, such as radioactive decay or induced nuclear reactions, represent fundamental processes involving matter and energy transformations.