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Oxidation-reduction reactions, commonly known as redox reactions, are fundamental chemical processes where electrons are transferred between two substances. It may be easy to remember if we frame it this way: in these reactions, one species is 'reducing' the other while also becoming 'oxidized' itself.

During a redox reaction, the substance that donates electrons is known as the reducing agent or reductant. Conversely, the substance that gains electrons is referred to as the oxidizing agent or oxidant. It's vital to note that the process of reduction denotes the gain of electrons, whereas oxidation indicates the loss of electrons.

For example, when iron rusts, iron atoms lose electrons and become iron ions, demonstrating oxidation, while oxygen molecules gain those electrons, showcasing reduction. This is a practical implication of redox reactions occurring in everyday life.

Electron transfer is the key component of oxidation-reduction reactions. To visualize this concept, imagine electrons as currency in a transaction between two chemicals in a reaction. The reducing agent 'pays' with electrons, whereas the oxidizing agent 'receives' the electrons.

But why are electrons transferred? Electrons are transferred because atoms seek to reach a more stable or lower-energy state which is often achieved by having a complete outer electron shell. This stability can be gained by losing, gaining, or sharing electrons with other atoms. In a redox reaction, the reducing agent provides this opportunity by transferring its electrons to another atom or molecule.

It's important to note that the transfer of electrons is not always a simple handover from one atom to another. At times, it involves complex electron-sharing arrangements, particularly in the case of covalent bonds. Nevertheless, the essence remains that electron transfer fundamentally changes the oxidation states of the involved substances.

A chemical change, quite distinct from a physical change, alters the chemical identity of a substance. In the context of a reducing agent in a redox reaction, chemical change is signaled by a transformation that involves a rearrangement of electrons within the substances involved.

When a reducing agent undergoes oxidation, it not only loses electrons but also experiences a change in its oxidation state, which is a significant aspect of its identity in a chemical reaction. This adjustment in the oxidation state generally leads to a new set of properties for the substance, marking a true chemical change. For instance, a metal that acts as a reducing agent might lose its metallic luster and become an ion in a compound.

Understanding chemical changes requires scrutinizing the electron configurations before and after reactions, predicting the behavior of substances based on their electron affinity, and acknowledging the alterability of their oxidation states. These transformations are pervasive in chemistry and vital for the function of batteries, biological systems, and even in the manufacturing of various materials.