Curium carbonate

The use of larger particles in the cyclotron, for example carbon, nitrogen or oxygen ions, enabled elements of several units of atomic number beyond uranium to be synthesised. Einsteinium and fermium were obtained by this method and separated by ion-exchange. and indeed first identified by the appearance of their concentration peaks on the elution graph at the places expected for atomic numbers 99 and 100. The concentrations available when this was done were measured not in gcm but in atoms cm. The same elements became available in greater quantity when the first hydrogen bomb was exploded, when they were found in the fission products. Element 101, mendelevium, was made by a-particle bombardment of einsteinium, and nobelium (102) by fusion of curium and the carbon-13 isotope. 

C22-0054. Identify the compound nucleus and final product resulting from each of the following nuclear reactions (a) carbon-12 captures a neutron and then emits a proton (b) the nuclide with eight protons and eight neutrons captures an a particle and emits a y ray and (c) curium-247 is bombarded with boron-11, and the product loses three neutrons. 

The name was debated. The priority for the production lay with the Institute for Nuclear Research in Dubna (Russia), under the leadership of G. N. Flerov, where 238U was bombarded with 22Ne. The half-life was about 2.7 seconds. At the University of California, bombardment of curium with carbon gave rise to an isotope with a half-life of 58 minutes. The IUPAC commission suggested the name "lerovium", but nobelium persisted. 

Group led by American Physicist Albert Ghiorso Synthesized by bombarding curium-244 and curium-246 with carbon-12 ions little is known of its properties named for Alfred Nobel, Swedish inventor of dynamite. 

Americium may be separated from other elements, particularly from the lanthanides or other actinide elements, by techniques involving oxidation, ion exchange and solvent extraction. One oxidation method involves precipitation of the metal in its trivalent state as oxalate (controlled precipitation). Alternatively, it may be separated by precipitating out lanthanide elements as fluorosilicates leaving americium in the solution. Americium may also he oxidized from trivalent to pentavalent state by hypochlorite in potassium carbonate solution. The product potassium americium (V) carbonate precipitates out. Curium and rare earth metals remain in the solution. An alternative approach is to oxidize Am3+ to Am022+ in dilute acid using peroxydisulfate. Am02 is soluble in fluoride solution, while trivalent curium and lanthanides are insoluble. 

Americium and other actinide elements may be separated from lanthanides by solvent extraction. Lithium chloride solution and an eight to nine carbon tertiary amine are used in the process. Americium is then separated from curium by the above methods. 

The element was discovered independently by several groups nearly simultaneously. In 1958, Ghiorso, Sikkeland, Walton, and Seaborg at Berkeley, California, synthesized an isotope of this new element by bombardment of a mixture of curium isotopes containing 95% Cm-244 and 4.5% Cm-246 with carbon-12 ions. This new element was named nobelium in honor of Alfred Nobel, discoverer of dynamite. 

Nohehum may he synthesized by several methods involving irradiation of isotopes of curium, plutonium, and fermium in the form of thin targets with heavy ions of boron, carbon, and oxygen using double-recod technique. The nuclear reaction in the synthesis of No-254 carried out by Ghiorso and his group is as foUows ... 

The analysis of the composite sample from the same series of curium-americium oxide production runs is presented in Table II. The content of carbon, the major impurity, is inferred rather than directly analyzed. The analyses of curium-americium oxide products generally reflect the purity of the feed, except for carbon and sulfur from the resin and a few potential corrosion products. 

The liquid is stirred vigorously (Note 8), and a solution of 60.0 g. (0.57 mole) of sodium carbonate in 350 ml. of water is added to the flask as rapidly as the concomitant evolution of curium dioxide will permit. Stirring is continued for about 15 ininiitoH after the addition is complete. The original reaction voshoI is rinsed with 200 ml. of petroleum ether (b.p. 60-75°) (Note 9), the rinse is added to the Krlenmcycr flask containing... 

The following equation shows an example of an artificial transmutation, as curium-244 is bombarded with carbon-12 to form nobelium-254 ... 

T. Seaborg at the Lawrence Radiations Laboratory, University of California, was later judged to be the first verified production. The researchers created nobelium by bombarding curium with carbon ions. Only minute quantities of nobelium have been produced, and it is of scientific interest only. The longest lasting isotope has a half-life of three minutes. 

Differences in behavior of actinides in the aquatic environment are shown by the data in Table VI. In WOL, we have noted that about 12% of the total Pu in the water column passes a 0.45-vim filter and also passes a 10,000 mol wt membrane filter. Essentially all of this soluble Pu is retained when passed through an anion exchange column. Curium-244 behaves somewhat differently in that about 50% of the activity in WOL water is soluble, but it also behaves anionically. The reasons for a negative charge on Pu and Cm are complex and are not understood, but one possible explanation is the presence of Pu(VI) carbonate complexes, analogous to the soluble uranyl carbonate complexes found in natural waters. Experiments are in progress to determine the valence state of this soluble form of Pu. Another explanation for the observed soluble Pu would be organic complexes. 

The discovery of element 102 was reported at the Nobel Institute for Physics in Stockholm in 1957, but experiments to date attempting to confirm its discovery have not been successful. The element was produced and positively identified, however, at the U.C. Radiation Laboratory in Berkeley in April 1958. It was made by bombarding curium (containing 96 protons) with carbon ions (containing 6 protons). 

In a similar manner, curium s 96 protons plus carbon s 6 protons gave us our first atoms of element 102. 

Cm is recovered from irradiated Pu/Al alloys and Am02(Pu02)/Al cermets by dissolution, extraction of plutonium with TBP in n-dodecane, extraction of americium and curium from the aqueous raffinate with 50 percent TBP in kerosene, purification of the americium and curium fraction by extraction with tertiary amines, and separation of americium by precipitation of the double carbonate K5 Am02 (003)3 A high-pressure ion-exchange system for the separation... 

There are two ways to produce a pure radionuclide not contaminated with any other radioactivity. An extremely pure target can be used with a reaction path which is unique. Alternatively, the radioactive products can be purified after the end of the bombardment. For example, a 10 g sample of zinc irradiated for one week with 10 n cm s yields a sample of Zn (ti 244 d) with 7.1 X 10 Bq. If, however, the zinc target is contaminated with 0.1% of copper, in addition to the zinc activity, 3.0 x 10 Bq of Cu (ti 12.7 h) is formed. In another example element 102 believed to be discovered initially in a bombardment of a target of curium by carbon ions. The observed activity, however, was later found to be due to products formed due to the small amount of lead inq)urity in the target. Similarly, in neutron activation of samarium it must be very free of europium contamination because of the larger europium reaction cross-sections. Handbooks of activation analysis oftra contain information on the formation of interfering activities from impurities. 

But bow to obtain them What nuclear reactions are suitable for that Fortunately, by the end of the fifties there was a definite answer to this question multiply charged ions of the light elements (carbon, oxygen, neon, argon) were to be used as bombarding particles. Then the targets could be made from conventional transuranium elements, namely, plutonium, americium, and curium and the problem with the target was resolved. Of course, it would be better... 

J. R. Walton and G. T. Seaborg bombarded curium with carbon ions and got the element 102, nohelium. From the 1960s the Russian Joint Institute for Nuclear Research at Dubna became a new, important center for research regarding the transuranium elements. In 1964 E. D. Donets, V. A. Schegolev and V. A. Ermakov verified the formation of nobehum by bombardment of curium with carbon (see Table 52.3). 

Nobelium-102 is synthesized from curium-96 by bombardment with carbon ions. The isotope obtained has a half-life of 55 seconds Lawrencium-103 is synthesized from califor-nium-98 by bombardment with boron and from americium by bombardment with oxygen. The isotopes Lr and Lr have half-lives of 3.9 and 28 seconds respectively... 

List the symbol and atomic number corresponding to each element. (a) carbon (b) nitrogen (c) sodium (d) potassium (e) copper 46. List the symbol and atomic number corresponding to each element (a) boron (b) neon (c) silver (d) mercury (e) curium... 

The addition of K2CO3 to Cm " solution causes Cm2(C03)3 to precipitate [158]. The compound is soluble in 40% K2CO3. Utilizing the insolubility of Cm(OH)3 in NaHC03 and the solubility of the Am(vi) carbonate complex (which is intensely colored), it is possible to reduce the americium content in curium to low levels. Sodium, rather than potassium, ion is necessary here to avoid precipitation of KAm02C03 [104]. 

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