Wikipedia:Today's featured article/July 21, 2011

Californium is the radioactive metallic chemical element with atomic number 98. It was first produced in 1950 by bombarding curium with alpha particles at the University of California, Berkeley. The element was named for California and the University of California. Two crystalline forms exist for californium under normal pressure, and a third exists at high pressure. Compounds of californium are dominated by a chemical form of the element, designated californium(III), that can participate in three chemical bonds. The most stable of californium's twenty known isotopes is californium-251, which has a half-life of 898 years. Californium-252, whose half-life is 2.645 years, is the most common isotope used. Californium can be used to help start up nuclear reactors, and is employed as a source of neutrons when studying materials with neutron diffraction and neutron spectroscopy. It can also be used in nuclear synthesis of higher mass elements; ununoctium was synthesized by bombarding californium-249 atoms with calcium-48 ions. Use of californium must take into account radiological concerns and the element's ability to disrupt the formation of red blood cells by bio-accumulating in skeletal tissue. (more...)

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