Oxygen is colorless, odorless and tasteless. Animals take up oxygen and convert it to carbon dioxide, while plants use carbon dioxide as a carbon source and release oxygen back into the atmosphere.
Oxygen is in group 16 of the periodic table. Because of its six valence electrons, this element is highly reactive and known to form compounds with nearly all other elements, either by direct reactions or displacement of elements from combinations that had already been formed. Many of these processes involve combustion, and others involve rust. Many ores of metal are oxides, such as iron oxide and mercury oxide.