The combination of oxygen and copper produces the substance called copper oxide. The formation of copper oxide requires a specific formula; the creation of this element ultimately produces a gas that resides in the atmosphere.
Oxygen and copper are quite different in their physical and chemical compositions, but nevertheless combine readily when exposed to each other. In addition to forming copper oxide, oxygen can be combined with copper to determine the percentage of oxygen in the surrounding air. This is accomplished by using gas syringes, which are used to measure the decrease in air volume that occurs when oxygen and copper combine.