THE NEW ELEMENT CALIFORNIUM (ATOMIC NUMBER 98)

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Definite identification has been made of an isotope of the element with atomic number 98 through the irradiation of Cm{sup 242} with about 35-Mev helium ions in the Berkeley Crocker Laboratory 60-inch cyclotron. The isotope which has been identified has an observed half-life of about 45 minutes and is thought to have the mass number 244. The observed mode of decay of 98{sup 244} is through the emission of alpha-particles, with energy of about 7.1 Mev, which agrees with predictions. Other considerations involving the systematics of radioactivity in this region indicate that it should also be unstable toward decay by ... continued below

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Thompson, S.G.; Street, K.,Jr.; Ghiorso, A. & Seaborg, G.T. June 19, 1950.

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Description

Definite identification has been made of an isotope of the element with atomic number 98 through the irradiation of Cm{sup 242} with about 35-Mev helium ions in the Berkeley Crocker Laboratory 60-inch cyclotron. The isotope which has been identified has an observed half-life of about 45 minutes and is thought to have the mass number 244. The observed mode of decay of 98{sup 244} is through the emission of alpha-particles, with energy of about 7.1 Mev, which agrees with predictions. Other considerations involving the systematics of radioactivity in this region indicate that it should also be unstable toward decay by electron capture. The chemical separation and identification of the new element was accomplished through the use of ion exchange adsorption methods employing the resin Dowex-50. The element 98 isotope appears in the eka-dysprosium position on elution curves containing berkelium and curium as reference points--that is, it precedes berkelium and curium off the column in like manner that dysprosium precedes terbium and gadolinium. The experiments so far have revealed only the tripositive oxidation state of eka-dysprosium character and suggest either that higher oxidation states are not stable in aqueous solutions or that the rates of oxidation are slow. The successful identification of so small an amount of an isotope of element 98 was possible only through having made accurate predictions of the chemical and radioactive properties.

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  • Report No.: UCRL--760
  • Report No.: AECD-2885
  • Grant Number: DE-AC02-05CH11231
  • DOI: 10.2172/932819 | External Link
  • Office of Scientific & Technical Information Report Number: 932819
  • Archival Resource Key: ark:/67531/metadc893365

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  • June 19, 1950

Added to The UNT Digital Library

  • Sept. 27, 2016, 1:39 a.m.

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  • Nov. 3, 2016, 8:13 p.m.

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Thompson, S.G.; Street, K.,Jr.; Ghiorso, A. & Seaborg, G.T. THE NEW ELEMENT CALIFORNIUM (ATOMIC NUMBER 98), report, June 19, 1950; Berkeley, California. (digital.library.unt.edu/ark:/67531/metadc893365/: accessed September 24, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.