Nuclear chemistry involves the study of radioactive decay, nuclear stability, and nuclear transformations. Radioactive decay occurs through alpha, beta, gamma, or positron emission, electron capture, or spontaneous fission. The rate of radioactive decay follows first order kinetics and is characterized by half-life. Radiometric dating uses radioactive decay to determine the age of materials. Nuclear stability depends on having an even number of protons and neutrons and being closest to the nuclear stability belt. Nuclear transformations can change the number of protons through various types of radioactive decay.