Berkelium elements

Seaborg, Ghiorso, and others went on to make berkelium (element 97) in 1949 and californium (element 98) in 1950. The JVisto Yorker wondered why they had not gone for broke, naming these two... 

Berkelium, element 97, was named after the city of Berkeley just as terbium previously had been named after the city of Ytterby, Sweden, where the rare earths were first found. 

In the actinides, the element curium, Cm, is probably the one which has its inner sub-shell half-filled and in the great majority of its compounds curium is tripositive, whereas the preceding elements up to americium, exhibit many oxidation states, for example -1-2, -1-3. -1-4, -1-5 and + 6, and berkelium, after curium, exhibits states of -1- 3 and -E 4. Here then is another resemblance of the two series. 

Kriterium eines Liickenelementes erftillt. Bei kritischer Betrachtung der Betastabi-litat der Isotope der Elemente Z > 92, kommt man zu der Erkenntnis, daB diese Moglichkeit bei Element 97, Berkelium, tatsachlich gegeben ist. 

Wie wir sahen, macht sich die magische Neutronenzahl N = 126 im Gebiet der radioaktiven Elemente durch die starke Zunahme der a-Zerfallsenergie bei Hinzukommen des 127- und 128. Neutrons bemerk-bar (vgl. Abb. 5 und 6). Kommt im Bereich des Berkeliums eine magische Neutronenzahl vor, SO wird Abb-10- -Zcrfallsencrgien der Californium-Iso-... 

These elements have all been named for famous scientists or for the places of their creation. For example, americium, berkelium, and californium were named after obvious geographical locations. Nobelium was named for the Nobel Institute, although later study proved it was not really created there. Curium was named for Marie Curie, the discoverer of radium. Einsteinium was named for the famous physicist, Albert Einstein. Fermium and lawrencium were named for Enrico Fermi and Ernest O. Lawrence, who made important discoveries in the field of radioactivity. Mendelevium was named for the discoverer of the periodic chart. 

Since plutonium is the actinide generating most concern at the moment this review will be concerned primarily with this element. However, in the event of the fast breeder reactors being introduced the behaviour of americium and curium will be emphasised. As neptunium is of no major concern in comparison to plutonium there has been little research conducted on its behaviour in the biosphere. This review will not discuss the behaviour of berkelium, californium, einsteinium, fermium, mendelevium, nobelium and lawrencium which are of no concern in the nuclear power programme although some of these actinides may be used in nuclear powered pacemakers. Occasionally other actinides, and some lanthanides, are referred to but merely to illustrate a particular fact of the actinides with greater clarity. 

Berkelium - the atomic number is 97 and the chemical symbol is Bk. The name is derived from Berkeley, the town in California where the element was first synthesized in 1949 by the... 

Berkelium is a metallic element located in group 11 (IB) of the transuranic subseries of the actinide series. Berkelium is located just below the rare-earth metal terbium in the lanthanide series of the periodic table. Therefore, it has many chemical and physical properties similar to terbium ( Tb). Its isotopes are very reactive and are not found in nature. Only small amounts have been artificially produced in particle accelerators and by alpha and beta decay. 

Because such small amounts of berkehum have been produced, not many uses for it have been found. One use is as a source for producing the element californium by bombarding isotopes of berkehum with high-energy neutrons in nuclear reactors. Berkelium is also used in some laboratory research. 

Californium is a transuranic element of the actinide series that is homologous with dysprosium (gjDy), just above it in the rare-earth lanthanide series. Cf-245 was the first isotope of californium that was artificially produced. It has a half-life of just 44 minutes. Isotopes of californium are made by subjecting berkelium to high-energy neutrons within nuclear reactors, as follows + (neutrons and A, gamma rays) — °Bk — °Cf + (3- (beta particle... 

Neither californium nor its compounds are found in nature. All of its isotopes are produced artificially in extremely small amounts, and all of them are extremely radioactive. All of its isotopes are produced by the transmutation from other elements such as berkelium and americium. Following is the nuclear reaction that transmutates californium-250 into cahfornium-252 Cf + (neutron and A, gamma rays) — Cf + (neutron and A, gamma rays) —> Cf. 

The actual situation with regard to the purity of most of the actinide metals is far from ideal. Only thorixun (99), uranium 11,17), neptunium 20), and plutonium 60) have been produced at a purity > 99.9 at %. Due to the many grams required for preparation and for accurate analysis, it is probable that these abundant and relatively inexpensive elements (Table I) are the only ones whose metals can be prepared and refined to give such high purities, and whose purity can be verified by accurate analysis. The purity levels achieved for some of the actinide metals are listed in Table II. For actinium (Ac), berkelium (Bk), californium (Cf),... 

This article presents a general discussion of actinide metallurgy, including advanced methods such as levitation melting and chemical vapor-phase reactions. A section on purification of actinide metals by a variety of techniques is included. Finally, an element-by-element discussion is given of the most satisfactory metallurgical preparation for each individual element actinium (included for completeness even though not an actinide element), thorium, protactinium, uranium, neptunium, plutonium, americium, curium, berkelium, californium, and einsteinium. 

Berkelium does not occur in nature. The element was synthesized in 1949 at the Lawrence Berkeley Laboratory in Berkeley, California hy Thompson, Ghiorso and Seahorg (Thompson, S.G., Ghiorso, A. and G. T. Seahorg. 1950. Phys. Rev., 77, 838). It has 12 isotopes. It is the fifth man-made transuranium element. Presently, the element has no commercial apphcation. 

The chemical properties of berkehum are rare earth-like character because of its half-filled 5/ subsheU and should be simdar to cerium. The element readily oxidizes to berkelium dioxide, Bk02 when heated to elevated temperatures (500°C). In aqueous solutions, the most common oxidation state is -i-3 which may undergo further oxidation to +4 state. A few compounds have been synthesized, the structures of which have been determined by x-ray diffraction methods. These include the dioxide, Bk02 sesquioxide, Bk203 fluoride,... 

Berkelium accumulates in the skeletal system. The radiation can cause damage to red blood cells. The maximum permissible body burden reported for the isotope Bk-249 in the human skeleton is 0.4 ng (Cunningham, B.B., 1968, Berkelium. In The Encyclopedia of the Chemical Elements. C.A. Hampel, ed., p. 48. New York Reinhold Book Corporation). 

Halides, 7 1-26 actinide elements, 2 195-233 anion dependence, 39 139 berkelium, 28 48, 51-53 beryllium, 14 255-332 binary, 35 237-246, 274-280 decomposition, 35 277 dichalcogen dihalides, 35 279-280 equilibrium studies, 35 242 mixed-ligand halides, 35 244-246 reactions, 35 246 selenium halides, 35 240-241... 

The next two elements, berkelium and cahfornium, were recently found to have identical structural sequences under pressure (Fig. 2 b, c). The first high pressure transition for both Bk and Cf is dhcp ccp as in the lanthanides. Thus the lanthanide character of heavy actinides again seems confirmed. But a second transition to the low symmetry a-uranium type structure follows in both metals. This transition reflects the start of 5 f participation in bonding. The transition pressures increase monotonically on going from Am to Bk and Cf 5, 7 and 17 GPa for the dhcp ccp transition, 10, 25, 30 GPa for the ccp An III (low symmetry phase) transition. The second transition in Cm occurs at 18 GPa this transition pressure fits well into the sequence of delocalization pressures. But the dhcp hep transition in Cm occurs at 12 GPa and thus does not fit into the increasing Z sequence with respect to both structure type formed and transition pressure. ... 

Continuation of the study of the radioactive elements produced by cyclotron bombardment of lower elements led in 1950 to isolation by tracer techniques of numbers 97 and 98. Bombardment of Am241 with helium ions by S. G. Thompson, A. Ghiorso, and G. T. Seaborg produced 97243 which resembled its analogue, terbium, in its elution from ion-cxchange resins. Since terbium was named from the city of Ytterby, 97 was named from the city in which so many new elements had been discovered, Berkeley, and the name berkelium and symbol Bk have been accepted (89, 90). 

Shortly after the announcement of the naming of berkelium A. P. Znoiko in Russia, who had made earlier predictions of the properties of element 97, suggested that Mendeleev should be honored by giving his name to this element, calling it mendelevium (95). The name berkelium had already been adopted, but, as will be seen, at the first opportunity the Berkeley group did honor the father of the periodic table. 

BERKELIUM. [CAS 7440-40-6]. Chemical element, symbol Bk, at. no. 97, at wt. 247 (mass number of the most stable isotope), radioactive metal of the Actinide series, also one of the Transuranium elements. All isotopes of berkelium are radioactive all must be produced synthetically. The element was discovered by G.T. Seaborg and associates at the Metallurgical Laboratory of the University of Chicago in 1949. At that time, the dement was produced by bombarding 241 Am with helium ions. 4i Bk is an alpha-emitter and may be obtained by alpha-bombardment of ,4Cm. 245Cm. or 246Ciu. Ollier nuclides include those of mass numbers 243—246 and 248-250. Probable electronic configuration ... 

The solubility properties of berkelium in its two oxidation states are entirely analogous to those of Lite actmide and lanLlianide elements in the corresponding oxidation states, Thus in the tripositive state such compounds as the fluoride and the oxalate arc insoluble in add solution, and the tetrapositive slate has such insoluble compounds as the lodate and phosphate in acid solution. The nitrate, sulfate, halides, perchlorate, and sulfide of both oxidation states are soluble,... 

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