Expanding the periodic table?

Whole new classes of compounds can be created from small clusters of atoms acting like single atoms of another element, researchers demonstrate for the first time in work reported in this week's Science. Clusters of 13 aluminum atoms behave like halogens and can combine with them to form halogen compounds with novel properties, the researchers write. And clusters of 14 aluminum atoms act like single alkaline earth atoms capable of forming ionic compounds that are in effect new types of salt.

This provides a compelling argument for redefining the periodic table of elements, according to Shiv Khanna, professor of physics at Virginia Commonwealth University and co-leader of the study. "We call these superatoms because I would classify [the 13-atom aluminum clusters] in the same position as iodine," Khanna told The Scientist. "Since the iodine position is already taken, I add a third dimension where [a 13-atom aluminum...