"Oxide" is not an element, but rather a compound containing oxygen. It's like asking for the atomic number of "salt" - salt is made of sodium and chlorine.

The atomic number of oxygen is 8. This means that each oxygen atom has 8 protons in its nucleus.

If you're interested in a specific oxide, like iron oxide (FeO) or carbon dioxide (CO2), you'd need to look at the atomic numbers of the individual elements in that compound.