Isotopes
In October 1971, it was announced that two new isotopes of element 105 were synthesized with the
heavy ion linear accelerator by A. Ghiorso and co-workers a Berkeley. Element 261-105 was produced
both by bombarding 250Cf with 15N and by bombarding 249Bk with 16O. The isotope emits 8.93-MeV
alpha particles and decays to 257Lr with a half-life of about 1.8 s. Element 262-105 was produced by
bombarding 249Bk with 18O. It emits 8.45 MeV alpha particles and decays to 258Lr with a half-life of
about 40 s. Seven isotopes of element 105 (unnilpentium) are now recognized.
Sources: CRC Handbook of Chemistry and Physics and the American Chemical Society.
Last Updated: 12/19/97, CST Information Services Team
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