Element 106 takes a seat at the table.

Seaborgium, the heavy element named after Glenn Seaborg, a winner of the 1951 Nobel Prize in Chemistry, has claimed its rightful place on the periodic table. Chemical experiments performed on a mere seven atoms of seaborgium place it firmly in the group that includes chromium, molybdenum, and tungsten.

On the basis of its atomic number, 106, that's exactly where seaborgium belongs. However, after previous experiments on elements 104 and 105--rutherfordium and hahnium (SN: 9/8/90, p. 150)--researchers weren't sure that seaborgium would fall into place so clearly. "In detail, we saw many differences in the behavior [of rutherfordium, and hahnium]," says Matthias Schadel of GSI, the heavy ion research center in Darmstadt, Germany. "This made us not so confident that the periodic table was a good ordering scheme for the heavy elements."

Schadel and an international team of scientists from Germany, Switzerland, Russia, and the United States synthesized seaborgium atoms in an accelerator, a painstakingly slow process that produced about one atom per hour, Schadel says. At temperatures of 300 [degrees] C and 400 [degrees] C, seaborgium formed the same kind of chemical compounds with thionyl chloride gas that molybdenum and tungsten would have under the same conditions.

The researchers also combined seaborgium with liquid acids, showing that the element remains neutral or forms negatively charged ions, as molybdenum and tungsten do, but not positively charged ions, as uranium does. The findings appear in the July 3 Nature.

Because researchers can't make bulk measurements of short-lived heavy elements, they must resort to "chemistry by analogy," says Ron Lougheed of the Lawrence Livermore (Calif.) National Laboratory. These first experiments on seaborgium are designed to reveal its gross chemical properties, he notes. Further experiments will reveal the details and any anomalies in its behavior.

So far, Schadel says, seaborgium "behaves as expected, which is nice to see, because then the architecture of the periodic table is still intact." The group is now analyzing data from a second experiment with seaborgium, and continuing its work on rutherfordium, and hahnium. "Maybe in a few years we will attack the next elements, 107 and 108, and see what we can do there," he says.