Tuesday, July 28, 2009

Guest feature: Element 112

By Larry Ferren

Some things never change. What may be a surprise to some is that the periodic table is not one of those things.

On Wednesday, June 10th, element 112, Ununbium was officially added to the periodic table, when scientists in Darmstadt, Germany, announced they had received official approval from an international body of chemists.

However, the discovery of the new element was not news to anyone in the scientific community. It had been discovered and announced back in 1996 when two atoms of it had been created in a 400-foot particle accelerator. It took 13 years to get their colleagues around the world to believe that they had created the element.

In years past, new elements were isolated by sifting through exotic minerals and isolating visible, earthy samples of new elements.

By 1940 new elements were created by colliding elements in particle accelerators and observing how the new elements decayed into daughter products, looking for the novel radioactive signatures in their data. This method worked up to elements of atomic number 107 or 108.

But elements even heavier than that fall apart too quickly to allow the chemists to do their work. When you're only dealing with one or two atoms of the new element, and when each was created months or even years apart during messy shoot-and-scatter experiments, it's almost impossible to separate the signal from the noise using traditional methods.

The evidence for Ununbium consists of a couple of computer blips stored on several hard drives in several competing labs around the word. A good share of the delay has been concerned with judging the authenticity of the data and which lab should get credit for the discovery.

Complicating this process are competing claims from Darmstadt Germany, Russia, Israel, and Japan, a claim of the Israeli team making premature discoveries, a claim of forged data from one of the Darmstadt team members, a withdrawal of one of the two atoms by the Darmstadt team, and repetition of the work by the Darmstadt team and the rediscovery of anther atom of Ununbium by that team in 2002. In the end, the Darmstadt team’s claim held, and it was awarded the discovery rights and naming rights.

With two atoms of Ununbium in existence for a brief fraction of a second it is impossible to predict or list any properties of this element. One can describe the decay chain that it underwent as it decayed once it formed. It emitted an alpha particle to produce element 110 which was Darmstadtium.

That element in turn emitted another alpha particle to produce element 108 which was Hassium. The name, Ununbium, is only temporary. This name is the Latin word for 112 and is assigned until the Darmstadt group gives the element its proper name this fall.

While Ununbium is the last element added to the periodic table, evidence for elements 113- 118 have been submitted to the same international body of chemists that ruled on Ununbium, so more elements are coming.

Larry Ferren is the chair of the Department of Chemistry at Olivet.

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