What process occurs when oxygen combines with another substance?

The process that occurs when oxygen combines with another substance is known as oxidation. In chemical terms, oxidation refers specifically to the loss of electrons by a substance as it reacts with oxygen or another agent, leading to the formation of oxides. This process is essential in various chemical reactions, including combustion, respiration, and corrosion.

During oxidation, the substance that donates electrons undergoes a change in its oxidation state. For example, when iron rusts, it reacts with oxygen in the presence of moisture, resulting in iron oxide, or rust. This transformation is a classic example of oxidation whereby iron (Fe) loses electrons to oxygen (O2), increasing its oxidation state.

In contrast, reduction is the opposite process, where a substance gains electrons, and neutralization involves the reaction between an acid and a base to form water and a salt. Corrosion typically refers to the degradation of materials, particularly metals, due to unwanted chemical reactions with environmental factors, which often involve oxidation but is not defined solely as the process of oxygen combining with another substance.