Atom breaks limit of lost electrons

Blasted with a laser, iridium sets record for highest oxidation state: +9

For atoms, bonding involves a give, take and sharing of electrons. For more than 100 years, scientists thought that eight electrons was the limit of a single atom’s generosity. But now it’s nine.

By blasting an iridium oxide compound with a laser, researchers detected the first atom, iridium, to give up nine of its electrons. Scientists had speculated that such a situation, called an oxidation state of plus nine, was possible. But researchers had previously been able to peel away only eight electrons or fewer from any atom. Because iridium has nine electrons in its outer layers, it was an excellent candidate for setting the new record.

The upped oxidation state allows the iridium to be a powerful oxidizer, capable of snatching electrons from other atoms. The finding opens new possibilities for myriad industrial chemical reactions as well as rewriting the rules of bonding, says inorganic chemist Gregory Girolami of the University of Illinois at Urbana-Champaign. “It changes all the textbooks,” he says.

The finding by Chinese, German and Canadian scientists appears in the Oct. 23 Nature.

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