The most common ion that oxygen can form is the oxide ion. In this form, a single oxygen atom gains an electrical charge of negative 2 and can readily bond with most other elements to form an oxidized compound.
Water is an abundant oxide which forms when two hydrogen atoms bond with an oxide ion. Another oxide ion compound that forms readily is ferric oxide, formed when 3 oxide ions bond with 2 iron (III) ions. This compound, in the presence of water, creates rust. Carbon can oxidize with one or two oxide ions forming carbon monoxide and carbon dioxide.