Isotope - Atoms with the same number of protons but different number of neutrons are called isotopes.
This article has a comprehensive list of radioactive elements and their properties.
Isotopes that undergo radioactive decay are called radioisotopes or radionuclides.
The decay process is not a chemical process, neither can it be controlled. Radioactive decay often poses health risk, especially those with intense radiation, as it penetrates the body and destroys biological cells.
In the case of radiocarbon dating, the half-life of carbon 14 is 5,730 years.
This half life is a relatively small number, which means that carbon 14 dating is not particularly helpful for very recent deaths and deaths more than 50,000 years ago.