Suboxides are a class of oxides wherein the electropositive element is in excess relative to the “normal” oxides. When the electropositive element is a metal, the compounds are sometimes referred to as “metal-rich”. Thus the normal oxide of caesium is Cs₂O, which is described as a Cs salt of O. A suboxide of caesium is Cs₁₁O₃, where the charge on Cs is clearly less than 1+, but the oxide is still described as O. Suboxides typically feature extensive bonding between the electropositive element, often leading to clusters.