Fermium-257 is a synthetic isotope of the element fermium, which is part of the actinide series on the periodic table. It has an atomic number of 100 and is produced through the bombardment of californium with neutrons. Fermium-257 has a half-life of about 100.5 days, making it relatively short-lived compared to other isotopes. This isotope is primarily used in scientific research, particularly in the fields of nuclear chemistry and physics. Due to its radioactivity, fermium-257 is not found naturally and must be created in specialized laboratories, often in facilities like nuclear reactors or particle accelerators.