noun
- An oxide containing the smallest proportion of oxygen relative to the metal or nonmetal element; the lowest oxide in a series of oxides of the same element.
Usage: chemistry; technical
Examples
- Copper protoxide, or cuprous oxide, contains less oxygen than cupric oxide.
- The protoxide of iron is formed when iron is oxidized under limited oxygen conditions.
- Chemists distinguish between the protoxide and higher oxides of the same element.
- Protoxide compounds were historically important in early chemical classification systems.