Berkelium

Radioactive and Artificially Produced Berkelium was first produced by Stanley G. Thompson, Glenn T. Seaborg, Kenneth Street, Jr. and Albert Ghiorso working at the __University__ of California, Berkeley, in December, 1949. They bombarded an isotope of americium, americium-241, with alpha particles with a device called a cyclotron. This created berkelium-243 and two __free__ neutrons. Berkelium's most stable isotope, berkelium-247, has a half-life of about 1,380 years. It decays into americium-243 through alpha decay. 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. Since only small amounts of berkelium have ever been produced, there are no known uses for berkelium and its compounds outside of basic scientific research.
 * Atomic Number:** 97
 * Atomic __Weight__:** 247
 * Melting Point:** 1323 K (1050°C or 1922°F)
 * Boiling Point:** Unknown
 * Density:** 14 grams per cubic centimeter
 * Phase at Room Temperature:** Solid
 * Element Classification:** Metal
 * Period Number:** 7 **Group Number:** none **Group Name:** Actinide
 * What's in a name?** Named for the city of Berkeley, California.
 * Say what?** Berkelium is pronounced as **BURK-lee-em**.
 * History and Uses:**
 * Number of Energy Levels:** 7
 * First Energy Level:**2
 * Second Energy Level:**8
 * Third Energy Level:**18
 * Fourth Energy Level:**32
 * Fifth Energy Level:**26
 * Sixth Energy Level:**9
 * Seventh Energy Level:**2

Isotopes

 * ** Isotope ** || ** Half Life ** ||
 * Bk-242 || 7.0 minutes ||
 * Bk-244 || 4.4 hours ||
 * Bk-245 || 4.9 days ||
 * Bk-247 || 1400.0 years ||
 * Bk-248 || 23.7 hours ||
 * Bk-249 || 320.0 days ||
 * Bk-250 || 3.22 hours ||
 * Bk-251 || 56.0 minutes ||

Facts
is a transuranic radioactive chemical element with the symbol **Bk** and atomic number 97, a member of the actinide and transuranium element series. It is named after the city of Berkeley California, the location of the [|University of California Radiation Laboratory] where it was discovered in December 1949. This was the fifth transuranium element discovered after neptunium, plutonium, curium and americium. The major isotops of berkelium, berkelium-249, is synthesized in minute quantities in dedicated high-flux nuclear reactors, mainly at the [|Oak Ridge National Laboratory] in Tennessee, USA, and at the [|Research Institute of Atomic Reactors] in Dimitrovgrad, Russia. The production of the second-important isotope berkelium-247 involves the irradiation of the rare synthetic isotope curium-224 with high-energy alpha particles. Just over one gram of berkelium has been produced in the United States since 1967. There is no practical application of berkelium outside of scientific research which is mostly directed at the synthesis of heavier transuranic elements and transactinides. A 22 milligram batch of berkelium-249 was prepared during a 250-day irradiation period and then purified for a further 90 days at Oak Ridge in 2009. This sample was used to synthesize the element ununseptium for the first time in 2009 at the [|Joint Institute for Nuclear Research], Russia, after it was bombarded with calcium-48 ions for 150 days. This was a culmination of the Russia—US collaboration on the synthesis of elements 113 to 118. Berkelium is a soft, silvery-white, radioactive metal. The berkelium-249 isotope emits low-energy electrons and thus is relatively safe to handle. However, it decays with a half-life of 330 days to californium-249, which is a strong and hazardous emitter of alpha particles. This gradual transformation is an important consideration when studying the properties of elemental berkelium and its chemical compounds, since the formation of californium brings not only chemical contamination, but also self-radiation damage, and self-heating from the emitted alpha particles.
 * Date of __Discovery__:** 1949
 * Discoverer:** G.T. Seaborg
 * Name Origin:** After Berkeley, California
 * Uses:** No uses known
 * Obtained From:** Man-made
 * Estimated Crustal Abundance:** Not Applicable
 * Estimated Oceanic Abundance:** Not Applicable
 * Number of Stable Isotopes:** 0
 * Ionization Energy:** 6.23 eV
 * Oxidation States:** +4, +3
 * Berkelium**



Little is known about the effects of berkelium on human body, and analogies with other elements may not be drawn because of different radiation products (electrons for berkelium and alpha particles and/or neutrons for most other actinides). The low energy of electrons emitted from berkelium-249 (less than 126 keV) hinders its detection, due to signal interference with other decay processes, but also makes this isotope relatively harmless to humans as compared to other actinides. However, berkelium-249 transforms with a half-life of only 330 days to the strong alpha-emitter californium-249, which is rather dangerous and has to be handled in a [|glove box] in a dedicated laboratory. [|[78]] Most available berkelium toxicity data originate from research on animals. Upon ingestion by rats, only about 0.01% berkelium ends in the blood stream. From there, about 65% goes to the bones, where it remains for about 50 years, 25% to the lungs (biological half-life about 20 years), 0.035% to the testicles or 0.01% to the ovaries where berkelium stays indefinitely. The balance of about 10% is excreted. [|[79]] In all these organs berkelium might promote cancer, and in the [|skeletal system] its radiation can damage red blood cells. The maximum permissible body burden for the isotope berkelium-249 in the human skeleton is 0.4 nanograms.

The fact that berkelium readily assumes oxidation state +4 in solids, and is relatively stable in this state in liquids greatly assists separation of berkelium away from many other actinides. These are inevitably produced in relatively large amounts during the nuclear synthesis and often favor the +3 state. This fact was not yet known in the initial experiments, which used a more complex separation procedure. Various oxidation agents can be applied to the berkelium(III) solutions to convert it to the +4 state, such as bromates (BrO3–), bismuthates (BiO3–), chromates (CrO42– and Cr2O72–), silver(I) thiolate ( Ag2S2O8 ), lead(IV) oxide (PbO2), ozone ( O3 ), or photochemical oxidation procedures. Berkelium(IV) is then extracted with ion exchange, extraction chromatography or liquid-liquid extraction using HDEHP (bis-(2-ethylhexyl) phosphoric scid), amines, tributyl phosphate or various other reagents. These procedures separate berkelium from most trivalent actinides and lanthanides, except for the lanthanide cerium (lanthanides are absent in the irradiation target but are created in various nuclear fission decay chains).[36home]

A more detailed procedure adopted at the Oak Ridge National Laboratory was as follows: the initial mixture of actinides is processed with ion exchange using lithium chloride reagent, then precipitated as hydroxides, filtered and dissolved in nitric acid. It is then treated with high-pressure elution from cation exchange resins, and the berkelium phase is oxidized and extracted using one of the procedures described above.[36home] Reduction of the thus-obtained berkelium(IV) to the +3 oxidation state yields a solution, which is nearly free from other actinides (but contains cerium). Berkelium and cerium are then separated with another round of ion-exchange treatment.[37home]