A chemical element, Cf , and atomic number 98, the ninth member of the actinide series of elements. Its discovery and creation have been based upon artificial nuclear transmutation of radioactive isotopes of lighter elements. All isotopes of californium are radioactive, with half-live ranging from a minute to about 1000 years. Because of its nuclear instability, californium does not occur in the Earth›s crust.
The chemical properties are similar to those observed for other 3+ actinide elements: a water-soluble nitrate, sulfate, chloride, and perchlorate. Californium is precipitated as the fluoride, oxalate, or hydroxide. Ion-exchange chromatography can be used for the isolation and identification of californium in the presence of other actinide elements. Californium metal is quite volatile and can be distilled at temperatures of the order of 1100-1200°C (2010-2190°F). lt is chemically reactive and appears to occur in three different crystalline forms between room temperature and its melting point, 900°C (1600°F).
The most easily formed isotope for many purposes is 252Cf, which is obtained in gram quantities in nuclear reactors and has a half-life of 2.6 years. lt decays partially by spontaneous fission, and has been very useful for the study of fission. lt has also had an important influence on the development of counters and electronic systems with applications not only in nuclear physics but in medical research as well.