Oxygen primarily forms covalent bonds rather than ionic bonds. This is largely due to its high electronegativity and the nature of its interactions with other elements.
In a covalent bond, atoms share electrons to achieve a full outer shell, which stabilizes them. Oxygen has six electrons in its outer shell and needs two more to complete it. When it bonds with nonmetals like hydrogen or carbon, it shares its electrons, resulting in molecules such as water (H2O) or carbon dioxide (CO2).
On the other hand, an ionic bond typically occurs between metals and nonmetals, where one atom loses electrons and another gains them, resulting in the formation of charged ions. Oxygen can participate in ionic bonding, but this is more common with metals, such as in the formation of metal oxides (e.g., magnesium oxide, MgO). In these cases, oxygen acts as an anion (O2-), but these reactions are primarily in the presence of metals and do not represent the more common bonding behavior of oxygen.
In summary, while oxygen can form ionic bonds under certain conditions, it predominantly forms covalent bonds with other nonmetals in most real-world scenarios.