Berkelium (Bk)

Science / Periodic Table of Elements / Berkelium (Bk): Atomic number: 97, Atomic mass: (247) g.mol -1, Electronegativity: unknown, Density: 14 g.cm3 at 20°C, Melting point: unknown, Boiling point: unknown, Vanderwaals radius: unknown, Ionic radius: unknown, Isotopes: 8, Discovered by: G.T. Seaborg 1949. Berkelium is a radioactive metallic element that is a member of the actinide group of elements. It is silvery in colour and its chemistry has been investigated to a limited extent and several compounds have been made. Berkelim metal is attacked by oxygen, steam and acids, but not by alkalis. Berkelium was synthesized at and is named after the University of California, Berkeley. The eighth member of the actinide transition series, berkelium was discovered in December 1949 by Thompson, Albert Ghiorso, and Glenn Seaborg, and was the fifth transuranium element synthesized. It was produced by cyclotron bombardment of milligram amounts of 241Am with helium ions at the Berkeley Radiation Laboratory. The first isotope produced had a mass of 243 and decayed with a half-life of 4.5 hours. Ten isotopes are now known and have been synthesized. The evidence of 249Bk with a half-life of 314 days, makes it feasible to isolate berkelium in weighable amounts so that its properties can be investigated with macroscopic quantities. One of the first visible amounts of a pure berkelium compound, berkelium chloride, was produced in 1962. It weighed 1 billionth of a gram. Berkelium probably has not yet been prepared in elemental form, but is expected to be a silvery metal, easily soluble in dilute mineral acids, and readily oxidized by air or oxygen at elevated temperatures to form the oxide. X-ray diffraction methods have been used to identify various compounds. As with other actinide elements, berkelium tends to accumulate in the skeletal system. Because of its rarity, berkelium presently has no commercial or technological use. Applications: No practical use of berkelium has do far emerged. Berkelium in the environment: The 10 isotopes of berkelium that are known are all radioactive; the element has not been found in the earth’s crust. Berkelium does not occur naturally on Earth.