The first decay processes to be discovered were alpha decay, beta decay, and gamma decay.
Alpha decay occurs when the nucleus ejects an alpha particle (helium nucleus). This is the most common process of emitting nucleons, but in rarer types of decays, nuclei can eject protons, or specific nuclei of other elements (in the process called cluster decay).
Beta decay occurs when the nucleus emits an electron or positron and a type of neutrino, in a process that changes a proton to a neutron or the other way around. The nucleus may capture an orbiting electron, converting a proton into a neutron (electron capture). All of these processes result in nuclear transmutation.
By contrast, there are radioactive decay processes that do not result in transmutation.
The energy of an excited nucleus may be emitted as a gamma ray in gamma decay, or used to eject an orbital electron by interaction with the excited nucleus, in a process called internal conversion. Highly excited neutron-rich radioisotopes (formed as the product of other types of decay) occasionally lose energy by emitting neutrons, and this results in a change in an element from one isotope to another. Another type of radioactive decay results in products that are not defined, but appear in a range of "pieces" of the original nucleus. This decay, which is called spontaneous fission, happens when a large unstable nucleus spontaneously splits into two (and occasionally three) smaller daughter nuclei, and generally immediately emits gamma rays, neutrons, or other particles as a consequence.
Alpha decay occurs when the nucleus ejects an alpha particle (helium nucleus). This is the most common process of emitting nucleons, but in rarer types of decays, nuclei can eject protons, or specific nuclei of other elements (in the process called cluster decay).
Beta decay occurs when the nucleus emits an electron or positron and a type of neutrino, in a process that changes a proton to a neutron or the other way around. The nucleus may capture an orbiting electron, converting a proton into a neutron (electron capture). All of these processes result in nuclear transmutation.
By contrast, there are radioactive decay processes that do not result in transmutation.
The energy of an excited nucleus may be emitted as a gamma ray in gamma decay, or used to eject an orbital electron by interaction with the excited nucleus, in a process called internal conversion. Highly excited neutron-rich radioisotopes (formed as the product of other types of decay) occasionally lose energy by emitting neutrons, and this results in a change in an element from one isotope to another. Another type of radioactive decay results in products that are not defined, but appear in a range of "pieces" of the original nucleus. This decay, which is called spontaneous fission, happens when a large unstable nucleus spontaneously splits into two (and occasionally three) smaller daughter nuclei, and generally immediately emits gamma rays, neutrons, or other particles as a consequence.