Jan. 31, 2004, 9:03PM
Scientists hope creation will expand periodic table
By JAMES GLANZ
New York Times
A team of Russian and American scientists are reporting today that they have
created two new chemical elements, called "superheavies" because of their
enormous atomic mass. The discoveries fill a gap at the furthest edge of the
periodic table and hint strongly at a weird landscape of undiscovered
The team, made up of scientists from Lawrence Livermore National Laboratory
in California and the Joint Institute for Nuclear Research in Dubna, Russia,
is disclosing its findings in a paper being published today in Physical
Review C, a leading chemistry journal. The paper was reviewed by scientific
peers outside the research group before publication.
"Two new elements have been produced," said Walt Loveland, a nuclear chemist
at Oregon State University who is familiar with the research. "It's just
incredibly exciting. It seems to open up the possibility of synthesizing
more elements beyond this."
The periodic table is the oddly shaped checkerboard that hangs in chemistry
classrooms the world over. Each element has a different number of protons,
particles with a positive electrical charge, in the dense central kernel
called the nucleus.
The number of protons, beginning with one for hydrogen, fixes an element's
place in the periodic table and does much to determine an element's chemical
Elements as heavy as uranium, No. 92 on the list, are found in nature, and
others have been created artificially. But much heavier elements have been
difficult to make, partly because they became increasingly unstable and
Still, for roughly half a century, nuclear scientists have been searching
for an elusive "island of stability," somewhere among the superheavies, in
which long-lived elements with new chemical properties might exist. Loveland
said the new results indicated that scientists might be closing in on that
The experiments took place at a cyclotron, a circular particle accelerator,
in Dubna, where the scientists fired a rare isotope of calcium at americium,
an element used in applications as varied as nuclear weapons research and
household smoke detectors.
Four times during a month of 24-hour-a-day bombardment, scientists on the
experiment said, a calcium nucleus fused with an americium nucleus and
created a new element.
Each calcium nucleus contains 20 protons; americium contains 95. Since the
number of protons determines where an element goes in the periodic table,
simple addition shows the new element to bear the atomic number 115, which
had never been seen before. Within a fraction of a second, the four atoms of
Element 115 decayed radioactively to an element with 113 protons. That
element had never been seen, either. The atoms of 113 lasted as long as 1.2
seconds before decaying radioactively to known elements.
Scientists generally do not give permanent names to elements and write them
into textbooks until the discoveries have been confirmed by another
laboratory. By an international convention based on the numbers, element 113
will be given the temporary name Ununtrium (abbreviated Uut for the periodic
table), and element 115 will be designated Ununpentium (Uup).
Loveland said he agreed that the new elements would require independent
confirmation before receiving acceptance. And he conceded that the find was
likely to receive more than the usual amount of scrutiny: Two years ago, the
reported discovery of Element 118 was retracted after a scientist at
Lawrence Berkeley National Laboratory was found to have fabricated evidence.
Bubba Do Wah Ditty
"Rarely is the question asked: Is our children learning?"
- Bushisms, 2000