Element Ununseptium to fill Periodic Table “GAP”

Welcome, ununseptium. With 117 protons , it is the latest super-heavy element, a discovery that fills a gap in the current periodic table of elements, and bolsters the idea that we may yet find an “island of stability” among heavyweight atoms
Uranium, which contains 92 protons, is the heaviest element that is stable in nature. But researchers have synthesised a number of even heftier elements.

This effort has created a host of new atoms, containing as many as 118 protons . But there has been a gap in the periodic table where element 117 might be.

Now a team of US and Russian researchers, led by Yuri Oganessian of the Joint Institute for Nuclear Research in Dubna, Russia, has filled it by firing calcium atoms into a target of berkelium atoms. They report the discovery in a paper to be published in Physical Review Letters.

Finding ununseptium was a lengthy process. Two collision runs each lasting 70 days turned up just six atoms of the new element, the New York Times and Science News report.

The raw stuff needed to produce the atoms was also hard to come by. To produce the berkelium – an element containing 97 protons – the researchers irradiated other targets, using a nuclear reactor at Oak Ridge National Laboratory in Tennessee. After some 250 days, they had made just 22 milligrams of the stuff.

Like its super-heavy mates, element 117 is quite short-lived, lasting just a fraction of a second. But the new atoms and the atoms they decay into continue an upward trend in the lifetime of super-heavy elements packed with more and more neutrons.

This pattern adds support to the idea that we could one day reach a long-suspected region called the “island of stability” , inhabited by super-heavy atoms with lifetimes of years or even longer. Some theories predict this island could be reached by atoms containing 184 neutrons and either 120 or 126 protons, the Times reports .

Until element 117 is confirmed, it has been given the placeholder name “ununseptium”. Getting an official name – a process that is handled by the International Union for Pure and Applied Chemistry – may take a while.

Copernicium, which contains 112 protons, was the last element to be named. It received its chemical symbol earlier this year , more than a decade after its initial discovery.


About Amod Agrawal

CS @ Illinois. Grad student.

Posted on 07/04/2010, in Chemistry. Bookmark the permalink. Leave a comment.

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