In redox (oxidation–reduction) chemistry, the process of gaining electrons is known as what?

Introduction / Context:
This question targets a very basic but fundamental idea in redox chemistry. Oxidation and reduction can be defined in several ways, including gain or loss of oxygen, gain or loss of hydrogen, and most generally loss or gain of electrons. You are asked to identify the correct term for the process in which a species gains electrons. This concept is essential in understanding electrochemistry, corrosion, metabolism and many industrial chemical processes.

Given Data / Assumptions:
Oxidation is commonly associated with loss of electrons, gain of oxygen or loss of hydrogen.
Reduction is commonly associated with gain of electrons, loss of oxygen or gain of hydrogen.
Radiation in this context refers to emission of energy as electromagnetic waves or particles and is not a synonym for an electron transfer process.
The options include a combination that suggests both oxidation and reduction, which must be evaluated carefully.

Concept / Approach:
The most general and robust definition of oxidation and reduction is in terms of electron transfer. Oxidation is defined as the loss of electrons by a species, increasing its oxidation number. Reduction is defined as the gain of electrons, decreasing its oxidation number. These definitions apply consistently across a wide variety of reactions, including those where no oxygen or hydrogen is involved. Therefore, when the question simply asks about the process of gaining electrons, it is pointing directly at the definition of reduction.

Step-by-Step Solution:
Step 1: Recall the mnemonic that oxidation is loss of electrons and reduction is gain of electrons. Many students remember this as the phrase oil rig, meaning oxidation is loss, reduction is gain. Step 2: Check the option oxidation. By definition, oxidation involves the loss of electrons, not the gain, so this cannot be correct. Step 3: Check the option reduction. Reduction is defined as the gain of electrons by an atom, ion or molecule, which matches the process described in the question. Step 4: Evaluate the option radiation. Radiation refers to emission of energy and is not used as a term for electron gain in standard redox terminology. Step 5: The option both oxidation and reduction is incorrect because oxidation and reduction are opposite processes in terms of electron transfer, although they always occur together in a redox reaction. The gain of electrons alone cannot be called both at the same time.

Verification / Alternative check:
Consider the half reaction Cu2+ + 2e minus gives Cu. In this process, cupric ion Cu2 plus gains two electrons to become metallic copper Cu. The oxidation number decreases from +2 to 0, and this half reaction is labelled a reduction half reaction. Similarly, in the reaction Fe3 plus + e minus gives Fe2 plus, the iron ion gains an electron and its oxidation number decreases, which is again defined as reduction. These standard examples confirm that gaining electrons corresponds to reduction, in agreement with the general definition used in electrochemistry and redox theory.

Why Other Options Are Wrong:
Oxidation is wrong because it refers to loss of electrons, often accompanied by an increase in oxidation number, the opposite of what is described in the question.
Radiation is wrong because it does not describe an electron transfer process; instead, it refers to energy emitted as waves or particles, such as in radioactive decay or electromagnetic radiation.
The option both oxidation and reduction is wrong because while oxidation and reduction always occur together in a full redox reaction, the specific act of gaining electrons is defined only as reduction, not as both processes simultaneously.

Common Pitfalls:
A common pitfall is to rely only on the older definition of oxidation as combination with oxygen and reduction as removal of oxygen, which can create confusion in reactions that do not involve oxygen at all. Another error is to mix up the directions of electron flow and words like loss and gain. Using a clear mnemonic and practising with half reactions where electrons are explicitly written on one side of the equation helps to fix the definition that reduction is gain of electrons and oxidation is loss of electrons.

Final Answer:
The process of gaining electrons in a redox reaction is called Reduction.