Radioactivity
The forces that bind protons and neutrons together in the nucleus usually are strong. However, insome isotopes, the nuclei are unstable because the forces binding protons and neutrons together are not strong enough. As a result, the nuclei spontaneously break apart(decay), a process called radioactivity What happens when unstable nuclei break apart? Three common types of radioactive decay are illustrated in Figure 11.15 and are summarized as follows