Americium-243

Overview
Americium-243 is a radioactive isotope of americium having 95 electrons and protons and 148 neutrons and has a mass of 243.06138 g/mol. It has a half-life of 7370 years and is highly unstable, hence it is not found in nature. It either decays by spontaneous fission or by emitting an alpha particle (the decay energy is 5.44MeV) to turn into neptunium-239.