Transcript: Radioactive decay is a phenomenon of the atomic nucleus. In these processes an element changes its chemical properties, that is its atomic number, by the emission of particles and or radiation. Radioactivity is a random process. It’s impossible to predict exactly when a particular radioactive decay will occur. However, in a collection of atoms there is a well defined half-life or time that it takes one starting point, that is the parent isotope, to turn into the decayed product or daughter isotope. Physicists early on did not understand the fundamental nature of the radioactive process, and they categorized the three types of decay as alpha decay, beta decay, and gamma decay.