Distinctive Characteristics of Al7Li: A Superatom Counterpart of Group IVA Elements.

A new superatom of dual valence states, namely Al7Li, has been proposed to further enrich the "three-dimensional periodic table". It bears great resemblance to group IVA elements in many aspects. Chief among them is that Al7Li favors both +2 and +4 oxidation states, which makes it analogous to the heavier carbon-group elements. Al7Li is capable of forming stable ionic compounds with carbon, oxygen, and fluorine and forming covalent tetrahydride with hydrogen, just as how germanium, tin, and lead atoms combine with these elements to form stable molecules. The nearest atomic counterpart of Al7Li in group IV is probably Sn or Pb since their oxides and tetrahydrides share like characteristics.