The reactant is iron (Fe) and the oxidizing agent is oxygen (O). This reaction results in the the formation of a compound known as iron oxide (Fe2O3), which is commonly referred to as rust. The reaction can be written as:
Fe + O2 --> Fe2O3
The oxidation process involves the loss of electrons from the Fe atoms, as oxygen gains electrons and is reduced. The electrons are transferred from the iron to the oxygen, resulting in the formation of iron oxide, which is an insoluble solid.