THE PROBLEM OF ELEMENTS 97 AND 98

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP80-00809A000600370232-3
• Release Decision: RIPPUB
• Original Classification: S
• Document Page Count: 3
• Document Creation Date: December 22, 2016
• Document Release Date: September 27, 2011
• Sequence Number: 232
• Publication Date: January 8, 1951
• Content Type: REPORT

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1
SECRET
CLASSIFICATION SECRET
CENTRAL INTELLIGENCE AGENCY REPORT
INFORMATION. FROM
FOREIGN DOCUMENTS OR RADIO BROADCASTS
SUBJECT Scientific - Nurlear physics,
transuranium elements
HOW
PUBLISHED Thrice-monthly periodical
WHERE
PUBLISHED 'Moscow/Leningrad
DATE
PUBLISHED 11 Oct 1950
LANGUAGE
CD NO.
DATE OF
DATE DIST. f Jan 1951
NO. OF PAGES 3
SUPPLEMENT TO
REPORT NO.
THIS IS UNEVALUATED INFORMATION
THIS DOCUNINT CONTAINS INFORM ON APFICTINN THE NATIONAL DVNMII
OT THE UNITID STATES WITHIN TNN N1ANINI OF ISPIONAIE ACT IO
U. !. C., 31 AND 11, AS AMENDED. ITS TRAMMISSION ON THE REVELATION
NINITIDC By LAW. I REPRODUCTION ON THIS FORM ISIP OHIBITED?IS PRD`
Doklady Akademii Nauk, SSSR, Novaya Seriya, Vol LXXIV, No 5, 1950, pp 92.7-921.
THE PROBLEM OF EL MENTS 97 and 98
A. P. Znoyko
V. I. Semishin
Submitted 13 Jul 1950
by S. I. Vavilov
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Shortly after?.the recently published report on the obtaining of element 97
at the University-6f California (S. G. Thompson, A. Ghiorso, and G. T. Seaborg;
Phys Rev, Vol LXXVII, 838, 1950), another report was received on the synthesis
of the following element 98. The isotope obtained, 9824, has alpha-radioactivity
with a half-lilt of. 43 minutes (G. T. Seaborg, Phys Rev, Vol L%XVIII, No 31 1950).
The properties of the Isotopic nuclei of element 97 were long ago'described ac-
curately in the USSR on the basis of the laws governin the periodic system of
atomic nuclei (A. P. Znoyko, DAN, Vol LXIX, No 2, 1949 The agree-
ment of experimentally obtained data with the properties predicted by A. P. Znoyko
for isotopes of these elements is rhown in Table 1.
Table 1. Comparison of Experimental and Predicted Data for Elements 97 and-98
Elements 97 and 98' Predicted From Periodic Obtained: E*erimentallyr
System of Atomic Nuclei
Isotope 97243 97244 9821+4 97243 97244* 98244
Type of radiation K K K K
Half-life bra bra min 4.8 hr 43 min
The K-capture determined experimentally as having ahalf-life of 4.8 hours
applies to isotope 97??:? 3 or to 97244?
Recently, Mendeleyev's periodic law has been developed with the purpose of
relating the periodically varying properties of atomic nuclei with the quantitative
characteristics of the nuclei. As is well-known, A. P. Znoyko succeeded in finding
a relationship between the variable properties of nuclei, their specific-charge,
_ . , .. ~?, . cat, .nn,:,;,. n . ,_c rua .I?,.r.c ~:cr.:.. , .
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and structure. On the basis of this relationship, he constructed a periodic
system of isotopic nuclei which is the most advanced de,relopmentTof the basic
The periodic system of atomic nuclei not only reveals a regular relation-
ship among the periodically varying properties of the known isotopic nuclei, but
also permits us to predict many isotopic nuclei unknown 'at present. In particular,
for element 97 it was'predicted that this element should have isotopes with masses
243 and 244 which must be unstable and characterized by K-capture with a half-life
measured in hours.
In their recently published article, Seaborg, Thompson, and Ghiorso stated
that element 97 was obtained by the action of alpha-particles upon an americium
isotope, Am2g. The nuclear reaction was describes by the equation:
11 . Het = 97243- 2n1'0 or
A76241f
Am297 + Het = 244 + np
It was established that the given isotope exhibits K-capture with a half-life
equal to 4.8 hours. It was proposed that this element be called berkelium and
given the symbol Bk.
Thus, the results obtained by the experimenters agree completely with the
data predictea by A. P. Znoyko.
The predictions, however, related not to one, but to several isotopes of ele-
ment 97, Which indicates the great effectiveness of Mendeleyev's method of prediction
and its important application to atomic and nuclear physics.
The periodic system of atomic nuclei permits us to determine the properties
of all isotopes of elements 97 and 98 (see Table 2). _
Element 97
Isotopic mass
Type of radio-
active decay
Half-life
Element 98
Isotopic mass
Type of radio-
active decay?
240 241 242 243 244 `245 246 247 248 249 250
243 244 245 246 247 248 249 250 251
min days hrs- yrs days yrs yrs yrs
days
The periodic system of elements, constructed on the basis of periodically
varying values of specific charge, defines the actinides as clear homologs.of the.
lanthanides. The new elements 97 and 98 chemically must be homologs of elements
65 and 66, Terbium and dysp.-osium.
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Consequently, the properties which are observed for the series Eu, Gd, Tb,
and Dy must also hold for elements of the series Am, Cm, 97, and 98.
As with Terbium, the main valent states of element 97 must be } 3 and 1. 4
and the former state should be most stable. The element may have 8 and 7 electrons
in the 5f level. Element 98 is a chemical analog of Dy and has a valency of 3.
it is very difficult in practice to isolate and. ' study. compounds of element
97 with mass 243 because the half-life of this isotope is extremely short. There-
fore, the chemical nature of element 97 should be-studied through its isotopes
with masses 246, 247, 248, and 249, which have longer half-lives.. For study of
element 98, the long-lived isotope with mass 250 might be obtained.
The effectiveness of MendeleyevIs method is clearly apparent from the brief
data given above on predicting the properties of elements 97 and 98. This method
will stimulate the development of the chemistry of atoms and nuclear physics.
Element 96 has been given the name "curium." ..Element 96 is followed by
element 97, which was predicted on the basis of the discovery of the periodic
system of atomic nuclei with the help of the Mendel2yev met!'od 2,years before
it was actually obtained. We propose, therefore, that this element be called
"mendeleyevium" and given the symbol Md.
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