H' at. wt. (natural) 1.007967
at. wt. (H') 1.007822
at. no. 1
m.p. - 259.140C
b.p. - 252.870C
density 0.08988 gm./l
density (liquid) 70.8 gm/i. (-2530C)
density (solid) 7016 gm/i. (-2620C)
valence 1.
Electronic configuration
| K |
L |
M |
N |
O |
P |
Q |
| 1 |
2 |
3 |
4 |
5 |
6 |
7 |
| s |
s p |
s p d |
s p d f |
s p d f |
s p d f |
s p d f |
| 1 |
|
|
|
|
|
|
ELEMENT 102 (see Nobelium)
ELEMENT 103 (see Lawrencium)
ELEMENTS 104, 105, and BEYOND. In 1964, workers
of the Joint Nuclear Research Institute at Dubna (U.S.S.R.)
bombarded plutonium with accelerated 113-115 MeV.
neon ions. By measuring fission tracks in a special glass with
a microscope, they detected an isotope that decays by spon-
taneous 'fission. They suggested that this isotope, which had
B-12
a ha~f-lile of 0.3 10.1 sec. might be 104260, produced by the
following reaction:
94Pu242 + 10Ne22~104260+4n.
Element 104, the first transactinide element, is expected to
have chemical properties similar to hafnium. It would, for
example, form a relatively volatile compound with chlorine
(a tetrachloride). The Soviet scientists have performed ex-
periments aimed at chemical identification, and have
attempted to show that the 0.3-sec. activity is more volatile
than that of the relatively nonvolatile actinide trichlorides.
This experiment does not fulfill the test of chemically separ-
ating the new element from all others, but it provides
important evidence for evaluation. New data, reportedly
issued by Soviet scientists, have reduced the half-life of the
isotope they worked with from 0.3 sec. to 0.15 sec. The
Berkeley Group thus far has not been able to duplicate or
confirm their work. The Dubna scientists suggest the name
kurchatovium and symbol Ku for Element 104, in honor of
Igor Vasilevich Kurchatov, l90~l960, late Head of Soviet
Nuclear Research. In 1969, Ghiorso, Nurmia, Harris, and
P. and F. Eskola of the Univ. of Calif., reported that they
positively identified two alpha-emitting isotopes of Element
104. These were formed by bombarding Cf249 with C12 and
C13 ions. Isotopes 104257 and 104259 are said to have been
identified by "milking" their daughters, No253 and No255.
The isotope 104257 is reported to have a 4.5-sec. a-particle
activity with a complex spectrum, while 104259 is also an
a emitter with a 2-sec. half-life. 104258 has also been ten-
tatively identified as an I 1-msec. spontaneous-fission
activity. The name of Element 104, therefore, is presently
open to question. Russian investigators have bombarded
americium-253 with ions of neon and find two a-particle
emitters with half-lives of less than 3 secs., which they attril>
ute to 105260 and 105261. Again, the Berkeley Group has
failed to confirm these results. The difficulties encountered
in this kind of investigation can be appreciated when it is
realized that only one atom is produced for each 20 hrs. of
bombardment. Both Soviet and U.S. scientists are now
planning larger particle accelerators for producing super-
heavy elements, such as Element 126, which may be relatively
stable.
© 1999 F. Davies
Delphi O.E.M. Co.
All rights reserved
Return to periodic table