Californium (Cf)

Isotopes of Californium 

Californium is a radioactive rare earth metal named after the state of California and the University of California at Berkeley, USA, where it was discovered in 1950 by Glenn T. Seaborg, Stanley G. Thompson, Albert Ghiorso and Kenneth Street.

Two crystalline forms exist for californium under normal pressure: one above 900 ºC and one below 900 ºC. A third form exists at high pressure. Californium slowly tarnishes in air at room temperature. Compounds of californium are dominated by a chemical form of the element, designated californium(III), that can participate in three chemical bonds. 

Californium has several practical applications. It can be used to help start up nuclear reactors; as a source of neutrons when studying materials with neutron diffraction and neutron spectroscopy; and in nuclear synthesis of higher-mass elements. 

The isotope Californium-252 is a strong neutron emitter: one microgram emits 170 million neutrons per minute, making it a biological hazard. 

Properties of Californium