Triiodide in the context of Hypervalent molecules

In chemistry, a hypervalent molecule (the phenomenon is sometimes colloquially known as expanded octet) is a molecule that contains one or more main group elements apparently bearing more than eight electrons in their valence shells. Phosphorus pentachloride (PCl₅), sulfur hexafluoride (SF₆), chlorine trifluoride (ClF₃), the chlorite (ClO−2) ion in chlorous acid and the triiodide (I−3) ion are examples of hypervalent molecules.