Chemistry at periodic table's edge.

Chemistry at periodic table's edge

Element 105 (dubbed hahnium by U.S. researchers and nielsbohrium by the Soviets,) at the outer reaches of the periodic table, is one of the more reluctant elements when it comes to revealing its chemical properties. For one thing, its half-life is a fleeting 35 seconds; for another, it's extremely hard to produce. When Darleane Hoffman and her colleagues at Lawrence Berkeley (Calif.) Laboratory recently produced it by bombarding berkelium-249 with oxygen-18 ions, they created only 47 hahnium-262 isotopes in 800 experiments.

The researchers, who used a rapid chemical separation technique, now report they have made the first observations of hahnium's chemical properties in solution. The technique involves collecting the berkelium reaction products on a microscope over slip and adding nitric acid. This turns hahnium into an insoluble complex that sticks to the glass surface while the other products are washed away. "The beauty of this separation method is that you can do it very rapidly [in 50 seconds] because it's quite simple,' says Hoffman.

The fact that hahnium in solution adheres to glass shows that it behaves like niobium and tantalum--hahnium's lighter-weight Group V cousins. It also suggests that hahnium, like the Group V elements, has a 5 oxidation state, which would confirm an earlier prediction that elements 89 to 103 to the left of hahnium on the periodic table exhibit very different chemical properties from elements 104 and 105.