Scientists say they’ve created two new chemical elements, but it’s too soon to say they’ll be added to the “periodic tables” of high school chemistry textbooks.
“We have just had the first and only experiment. A single result doesn’t make a discovery,” said Yuri Oganessian, the leading Russian physicist whose group reported discovering elements 113 and 115.
“We must conduct a whole series of further experiments.”
The scientists said the two new “superheavy elements” existed briefly after being created in a particle accelerator at the Joint Institute of Nuclear Research in Dubna near Moscow. They collaborated with American scientists from Lawrence Livermore National Laboratory in California.
The elements represent unusual forms of matter with properties that go well beyond those of the 92 elements that occur naturally on Earth. Superheavies may be abundantly generated by supernova explosions in stars. Or perhaps they were fused during the fiery moments that signaled the dawn of the universe.
Here on the ground, such elements formed in atom smashers probably will never find an everyday use. Yet their “birth” adds details to a broader — and very competitive — scientific inquiry to establish a single, unified theory that would explain the physical forces that govern the behavior of all matter.
The report on the new elements appears in the February issue of the journal Physical Review C, a publication of the American Physical Society that specializes in nuclear structure.
The discoveries will not be fully accepted and added to textbooks until other labs create the elements, a process that could take months or even years.
Oganessian said he hoped other labs will repeat the experiment and take the research further.
“As of today,” he said, “this is just a single fact which needs to be confirmed.”
Confidence in nuclear structure experiments was shaken when the purported 1999 discovery of two elements was found to be false. But researchers familiar with the newly reported work said they were confident in the latest results.
“The paper is solid,” said Richard Casten, a Yale physicist and an editor for the journal publishing the work.
He described the techniques as “very tricky,” but he and others expressed confidence in the results and the scientists involved.
“I’m confident that the process was good,” Casten said. “Yuri is a very well-respected and careful guy.”
Calcium and americium fused
In the experiments, researchers fired a rare isotope of calcium at a target made from americium. The new element 115 was created on occasions when the nuclei of the calcium and americium fused.
In the artificial environs of the cyclotron, atoms of element 115, now labeled ununpentium, apparently lasted less than one-tenth of a second before it decayed into element 113. The atoms of element 113, known as ununtrium, persisted for more than a second.
The 115 and 113 are the new elements’ atomic numbers, which refer to the number of protons in their nuclei.
In nature, scientists theorize, they would belong to a special class of superheavy elements that have a much longer life because the shell-like structures of their nuclei contain the highest numbers of precisely arranged protons and neutrons.
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