Californium Californium Californium is a radioactive chemical element with symbol Cf and atomic number 98. The element was first synthesized in 1950 at the Lawrence Berkeley National Laboratory (then the University of California Radiation Laboratory), by bombarding curium with alpha particles (helium-4 ions). It is an actinide element, the sixth transuranium element to be synthesized, and has the second-highest atomic mass of all the elements that have been produced in amounts large enough to see with the unaided eye (after einsteinium). The element was named after the university and the state of California. Two crystalline forms exist for californium under normal
Californium compounds hexagonal structure. Californium(III) iodide (CfI) is a lemon-yellow solid that has a rhombohedral structure and sublimes at ~800 °C. Californium(III) oxyfluoride (CfOF) is prepared by hydrolysis of californium(III) fluoride (CfF) at high temperature. Californium(III) oxychloride (CfOCl) is prepared by hydrolysis of the hydrate of californium(III) chloride at 280–320 °C. Heating the sulfate in air at about 1200 °C and then reducing with hydrogen at 500 °C produces the sesquioxide (CfO). The hydroxide Cf(OH) and the trifluoride CfF are slightly soluble. Californium(III) oxychloride (CfOCl) was the first californium compound to be discovered. Californium(III) polyborate is unusual in that californium is covalently