Californium elements

The Multi-Purpose Processing Facility was installed in F Canyon (reprocessing plant) at SRP for separation of Californium and trans-californium elements using newly developed, high-pressure, chromatographic cation exchange processes. 

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... 

Californium, element 98, is similar to dysprosium, but it was simply named after the university and the state where the work was done. The discoverers of californium explained their choice in naming the element as follows ... 

The identification of element 98 was accomplished with a total of only 5,000 atoms (Thompson et al. 1950b). The ion-exchange techniques were also used in the separation and identification of californium. Element 98 was eluted in the expected fraction, and the observed half-life and ot-particle energy of the radioactivity were also in agreement with predictions. It was named after the state of its discovery, although the chemical analog of element 98 was dysprosium (Dy). 

The actinides offer a greater range of oxidation states in their fluorides than do the lanthanides, particularly in the first half of the series. The oxidation states of the actinide fluorides are shovm in Table 7.3. The pattern of stable oxidation states is very much like those of the transition elements rather than like the lanthanides, but towards the half-full 5f orbitals stage and beyond the actinides tend to mirror the lanthanides. The trans-californium elements are not included in Table 7.3. They are more lanthanide-like and form only +3 fluorides. 

Ernest O. Lawrence, inventor of the cyclotron) This member of the 5f transition elements (actinide series) was discovered in March 1961 by A. Ghiorso, T. Sikkeland, A.E. Larsh, and R.M. Latimer. A 3-Mg californium target, consisting of a mixture of isotopes of mass number 249, 250, 251, and 252, was bombarded with either lOB or IIB. The electrically charged transmutation nuclei recoiled with an atmosphere of helium and were collected on a thin copper conveyor tape which was then moved to place collected atoms in front of a series of solid-state detectors. The isotope of element 103 produced in this way decayed by emitting an 8.6 MeV alpha particle with a half-life of 8 s. 

Each of the elements has a number of isotopes (2,4), all radioactive and some of which can be obtained in isotopicaHy pure form. More than 200 in number and mosdy synthetic in origin, they are produced by neutron or charged-particle induced transmutations (2,4). The known radioactive isotopes are distributed among the 15 elements approximately as follows actinium and thorium, 25 each protactinium, 20 uranium, neptunium, plutonium, americium, curium, californium, einsteinium, and fermium, 15 each herkelium, mendelevium, nobehum, and lawrencium, 10 each. There is frequently a need for values to be assigned for the atomic weights of the actinide elements. Any precise experimental work would require a value for the isotope or isotopic mixture being used, but where there is a purely formal demand for atomic weights, mass numbers that are chosen on the basis of half-life and availabiUty have customarily been used. A Hst of these is provided in Table 1. 

The effects of a rather distinct deformed shell at = 152 were clearly seen as early as 1954 in the alpha-decay energies of isotopes of californium, einsteinium, and fermium. In fact, a number of authors have suggested that the entire transuranium region is stabilized by shell effects with an influence that increases markedly with atomic number. Thus the effects of shell substmcture lead to an increase in spontaneous fission half-Hves of up to about 15 orders of magnitude for the heavy transuranium elements, the heaviest of which would otherwise have half-Hves of the order of those for a compound nucleus (lO " s or less) and not of milliseconds or longer, as found experimentally. This gives hope for the synthesis and identification of several elements beyond the present heaviest (element 109) and suggest that the peninsula of nuclei with measurable half-Hves may extend up to the island of stabiHty at Z = 114 andA = 184. 

L. CrandaH, Production ofBerkelium and Californium, Proceedings of the Symposium Commemorating the 25th Anniversary of Elements 97 and 98 held on January 20, 1975, Lawrence Berkeley Laboratoy, Report HBL-4566. Available as TID 4500-R64 from National Technical Information Center, Springfield, Va., 1975. 

Albert Ghiorso ( 1915) together with Torbjorn Sikkeland, Almon Larsh, and Robert M. Latimer obtained the element by bombarding californium 1 with boron ions. 

The element was generated by bombardment of californium with boron in a linear accelerator. The priority is debated. Isotopes of the elements were observed both by the group of Glenn T. Seaborg and by that of G. N. Flerov in Dubna. IUPAC proposed that the priority be shared. The longest-lived isotope has a half-life of 200 minutes. Lawrencium ends the series of actinides, as the 5f level is fully occupied with 14 electrons. 

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. 

A kind of summary of the similarities which, albeit with some uncertainties, may be evidenced between the single lanthanide and actinide metals is reported, according to Ferro et al. (2001a) in Fig. 5.13. According to this scheme the alloying behaviour of plutonium could be simulated by cerium whereas a set of similarities may especially be considered between the block of elements from praseodymium to samarium with those from americium to californium. 

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. 

Californium - the atomic number is 98 and the chemical symbol is Cf. The name derives from the state and the university of California, where the element was first synthesized. Although the earlier members of the actinide series were named in analogy with the names of the corresponding members of the lanthanide series, the only connection with the corresponding element dysprosium (Greek for hard to get at) that was offered by the discoverers was that searchers for another element (gold about a century before in 1849) foimd it difficult to get to California. An American scientific team at the University of California lab in Berkeley,... 

California under Gleim T. Seaborg used the nuclear reaction Cm ( He, n) Cf to first detect the element californium in 1950. The longest half-life associated with this unstable element is 900 year Cf. 

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 synthetic radioactive transuranic element of the actinide series. The pure metal form is not found in nature and has not been artificially produced in particle accelerators. However, a few compounds consisting of cahfornium and nonmetals have been formed by nuclear reactions. The most important isotope of cahfornium is Cf-252, which fissions spontaneously while emitting free neutrons. This makes it of some use as a portable neutron source since there are few elements that produce neutrons all by themselves. Most transuranic elements must be placed in a nuclear reactor, must go through a series of decay processes, or must be mixed with other elements in order to give off neutrons. Cf-252 has a half-life of 2.65 years, and just one microgram (0.000001 grams) of the element produces over 170 mhhon neutrons per minute. 

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. 

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