Final answer:
In modern scientific terms, oxidation is defined as the loss of electrons during a chemical reaction resulting in an increase in the oxidized substance's charge. Oxidation is part of redox reactions, where one species is oxidized and another reduced, playing a critical role in processes like corrosion, photosynthesis, and digestion.
Step-by-step explanation:
In its modern scientific sense, oxidation refers to a chemical reaction in which a substance loses one or more electrons. When this electron loss occurs, the substance that loses electrons is said to be oxidized, which corresponds to an increase in its charge.
This is because electrons have a negative charge, so when a substance loses electrons, it ends up with a higher positive charge. The term redox, short for oxidation and reduction, represents two types of chemical reactions that occur simultaneously: one species is oxidized and another is reduced. Reduction is the opposite of oxidation, referring to the gain of electrons.
Corrosion and combustion are classic examples of oxidation in which substances react with oxygen. For instance, when iron rusts, it forms an iron oxide, and it is said to be oxidized because it has lost electrons to oxygen.
Similarly, aluminum forms a protective layer of aluminum oxide upon exposure to air because it transfers electrons to oxygen. In biological systems, most chemical processes, like photosynthesis and the digestion of food, are redox reactions. Therefore, oxidation is crucial in understanding the energy transactions in these processes.