Chemical Properties of Elements 99 and 100 Page: 3 of 36

UCRL-2591 Rev.

S. G. Thompson, B. G. Harvey, G. R. Choppin and G. T. Seaborg
Department of Chemistry and Radiation Laboratory
University of California, Berkeley, California
July 23, 1954
Isotopes of elements 99 and 100 have been produced by neutron
irradiation of Pu239; the final steps in their production are indicated
by the following reaction sequence:1-5
252 253 1- 253 254 R- 254
- Cf (nr)Cf 20_ 99 (n,y)99 36 100 .
The properties of some of the isotopes thus produced are listed in Table
I. These were the isotopes used for the present tracer studies of the
chemical properties of the new elements.
Table I
Isotope Radiations Half-Life
99253 6.68 Mev a -20 days
99254 1.1 Mev ~ 36 hours
100254 7.22 Mev a 3.2 hours
The first separation and identification of the new elements proved
that prior expectations concerning the stability of their tripositive
states, their precipitation properties and exchange column elution
sequences were correct; in short, that they are chemically very similar
to their actinide predecessors,7,8 differing in the manner to be expected
for ions of somewhat smaller radius.


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Thompson, S. G.; Harvey, B. G.; Choppin, G. R. & Seaborg, G. T. Chemical Properties of Elements 99 and 100, report, July 23, 1954; Berkeley, California. ( accessed May 20, 2019), University of North Texas Libraries, Digital Library,; crediting UNT Libraries Government Documents Department.

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