1s² 2s²p⁶ 3s²p⁶d¹⁰ 4s²p⁶d¹⁰f¹⁴ 5s²p⁶d¹⁰f⁸ 6s²p⁶d¹ 7s²

  History

(Berkeley, home of the University of California) Berkelium, the eighth member of the actinide transition series was the fifth transuranium element synthesized.  Berkelium was first synthesized by Glenn T. Seaborg, Albert Ghiorso, Stanley G. Thompson, and Kenneth Street, Jr at the University of California, Berkeley in December 1949.  The team used a cyclotron to bombard a milligram-sized target of ²⁴¹Am with alpha particles to produce ²⁴³Bk (half-life 4.5 hours) and two free neutrons.   One of the longest lived isotopes of the element, ²⁴⁹Bk (half-life 330 days), was later synthesized by subjecting a ²⁴⁴Cm target with an intense beam of neutrons.

Characteristics

Weighable amounts of ²⁴⁹Bk (half-life 314 days) make it possible to determine some of its properties using macroscopic quantities.  The first visible amounts of a berkelium compound, berkelium chloride (BkCl₃) was produced in 1962 and weighed about 3 billionths of a gram (0.000000003 grams).  Berkelium oxychloride (BkOCl), berkelium fluoride (BkF₃), berkelium dioxide (BkO₂) and berkelium trioxide (BkO₃) have been identified and studied with a method known as X-ray diffraction.  As with other actinide elements, berkelium tends to accumulate in the skeletal system.  The maximum permissible body burden of ²⁴⁹Bk in the human skeleton is about 0.0004 ug.  Because of its rarity, berkelium presently has no known uses outside of basic research and plays no biological role.  As of 2004 it had not been isolated in its elemental form, but it is predicted to be a silvery metal that would easily oxidize in air at elevated temperatures and would be soluble in dilute mineral acids. Berkelium-249 is available from O.R.N.L. at a cost of $160/ug plus packing charges.

As of 2004, it had not been isolated in its elemental form, but it is predicted to be a silvery metal that would easily oxidize in air at elevated temperatures and would be soluble in dilute mineral acids.

Compounds

Isotopes

19 radioisotopes of berkelium have been characterized, with the most stable being ²⁴⁷Bk with a half-life of 1380 years, ²⁴⁸Bk with a half-life of >9 years, and ²⁴⁹Bk with a half-life of 330 days.  All of the remaining radioactive isotopes have half-lives that are less than 5 days, and the majority of these have half-lives that are less than 5 hours.  This element also has 2 meta states, with the most stable being ^248mBk (t_½ 23.7 hours).  The isotopes of berkelium range in atomic weight from 235.057 amu (²³⁵Bk) to 254.091 amu (²⁵⁴Bk).

Precautions

Like other actinides, berkelium bio-accumulates in skeletal tissue.  This element has no known uses outside of basic research and plays no biological role.