Nobelium elements

Table 2.8 lists several ionization energies notice that all of them are positive. Figure 2.15 depicts the first ionization energies /(i) (as y) for the elements hydrogen to nobelium (elements 1-102) drawn as a function of atomic number (as x). 

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. 

Element 106 was created by the reaction 249Gf(180,4N)263X, which decayed by alpha emission to rutherfordium, and then by alpha emission to nobelium, which in turn further decayed by alpha between daughter and granddaughter. The element so identified had alpha energies of 9.06 and 9.25 MeV with a half-life of 0.9 +/- 0.2 s. 

In 1957 workers in the United States, Britain, and Sweden announced the discovery of an isotope of element 102 with a 10-minute half-life at 8.5 MeV, as a result of bombarding 244Gm with 13G nuclei. On the basis of this experiment, the name nobelium was assigned and accepted by the Gommission on Atomic Weights of the International Union of Pure and Applied Ghemistry. 

Following tradition giving the right to name an element to the discoverer(s), the Berkeley group in 1967, suggested that the hastily given name nobelium along with the symbol No, be retained. 

Sixteen isotopes of fermium are known to exist. 257Fm, with a half-life of about 100.5 days, is the longest lived. 250Fm, with a half-life of 30 minutes, has been shown to be a decay product of element 254-102. Chemical identification of 250Fm confirmed the production of element 102 (nobelium). 

Lawrencium behaves differently from dipositive nobelium and more like the tripositive elements earlier in the actinide series. 

The other actinides have been synthesized in the laboratory by nuclear reactions. Their stability decreases rapidly with increasing atomic number. The longest lived isotope of nobelium (102N0) has a half-life of about 3 minutes that is, in 3 minutes half of the sample decomposes. Nobelium and the preceding element, mendelevium (ioiMd), were identified in samples containing one to three atoms of No or Md. 

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. 

Nobelium - the atomic number is 102 and the chemical symbol is No. The name derives from Alfred Nobel , the discoverer of dynamite and founder of the Nobel prizes. It was first synthesized in 1966 by the Russian scientists from the JINR (Joint Institute for Nuclear Research) lab in Dubna, Russia under Georgi Flerov. Earlier claims to have synthesized Nobelium beginning in 1957 were shown to be erroneous but the original name was retained because of its videspread use throughout the scientific literature. The longest half-life associated with this unstable element is 58 minute o. 

ORIGIN OF NAME Tantalum was named after Tantalus, who was the father of Niobe, the queen of Thebes, a city in Greek mythology. (Note The element tantalum was originally confused with the element nobelium.)... 

Nobelium is the next to last transuranic element of the actinide series. The transuranic elements are those of the actinide series that are heavier than uranium. Nobehum is also the heaviest element of the vertical group 16 (VIA). 

Three groups had roles in the discovery of nobelium. First, scientists at the Nobel Institute of Physics in Stockholm, Sweden, used a cyclotron to bombard Cu-244 with heavy carbon gC-13 (which is natural carbon-12 with one extra neutron). They reported that they produced an isotope of element 102 that had a half-life of 10 minutes. In 1958 the team at Lawrence Laboratory at Berkeley, which included Albert Ghiorso, Glenn Seaborg, John Walton, and Torbjorn Sikkeland, tried to duplicate this experiment and verify the results of the Nobel Institute but with no success. Instead, they used the Berkeley cyclotron to bombard cerium-... 

The transeinsteinium actinides, fermium (Fm), mendelevium (Md), nobelium (No), and lawrencium (Lr), are not available in weighable (> ng) quantities, so these elements are unknown in the condensed bulk phase and only a few studies of their physicochemical behavior have been reported. Neutral atoms of Fm have been studied by atomic beam magnetic resonance 47). Thermochromatography on titanium and molybdenum columns has been employed to characterize some metallic state properties of Fm and Md 61). This article will not deal with the preparation of these transeinsteinium metals. 

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. 

In 1957 a group of scientists at the Argonne Laboratory, the Atomic Energy Research Establishment at Harwell, England, and the Nobel Institute for Physics in Stockholm announced the isolation of element 102 (103). They proposed the name nobelium for this element. However, workers at the University of California Radiation Laboratory could not confirm this claim (104), but did identify the isotope 102254 which they obtained by bombardment of Cm246 with C12 ions in the linear accelerator. They did not immediately propose a name to replace the name nobelium (105). 

In contrast to the lanthanide 4f transition series, for which the normal oxidation state is +3 in aqueous solution and in solid compounds, the actinide elements up to, and including, americium exhibit oxidation states from +3 to +7 (Table 1), although the common oxidation state of americium and the following elements is +3, as in the lanthanides, apart from nobelium (Z = 102), for which the +2 state appears to be very stable with respect to oxidation in aqueous solution, presumably because of a high ionization potential for the 5/14 No2+ ion. Discussions of the thermodynamic factors responsible for the stability of the tripositive actinide ions with respect to oxidation or reduction are available.1,2... 

Lawrencium has been found lo behave quite differently from dipositivc nobelium and. in fact, il is comparable to the hiposilivc elements that appear earlier in the Actinide series. 

In 1973, scientists at Oak Ridge National Laboratory and Lawrence Berkeley Laboratory, produced a relatively long-lived isotope of nobelium through the bombardment of 248C,m with 1 0 ions. A total half-title of 58-5 minutes was computed from the combined data of both laboratories, See also Chemical Elements... 

TRANSACTINIUM EARTHS. A group of chemical elements more frequently termed the Actinides. In order of increasing atomic number, they indude actinium, thorium, protactinium, uranium, neptunium, plutonium, americium, curium, berkelium, californium, einsteinium, fermium, mendelevium, nobelium. and lawrencium. See also Actinide Contraction. 

Starting with the method described above, extensive tables of the numerical values of mean energies, integrals of electrostatic and constant of spin-orbit interactions are presented in [137] for the ground and a large number of excited configurations, for atoms of boron up to nobelium and their positive ions. They are obtained by approximation of the corresponding Hartree-Fock values by polynomials (21.20) and (21.22). Such data can be directly utilized for the calculation of spectral characteristics of the above-mentioned elements or they can serve as the initial parameters for semi-empirical calculations [138]. 

The lanthanide elements begin with lanthanum (atomic number 57) and go to ytterbium (atomic number 70). The actinide elements begin with actinium (atomic number 89) and go to nobelium (atomic number 102). 

Actinides The elements from actinium (atomic number 89) to nobelium (atomic number 102). 

The effect of Coulomb repulsion on the cross section starts to act severely for fusion reactions to produce elements beyond fermium. From there on a continuous decrease of cross section was measured from microbams for the synthesis of nobelium down to picobarns for the synthesis of element 112. Data obtained in reactions with Pb and Bi for the In-evaporation channel at low excitation energies of about 10-15 MeV (therefore named cold fusion) and in reactions with actinide targets at excitation energies of 35-45 MeV (hot fusion) for the 4n channel are plotted in Figure 7a and b, respectively. 

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