Question

Why is it that when something gains electrons, it is said to be reduced? What is being reduced?

Short answer

In a redox reaction, when something gains electrons, it is said to be reduced because its oxidation state has been decreased. The term "reduced" originates from early chemistry, where it was thought to mean the removal of oxygen. However, it now refers to the gain of electrons and the reduction of the oxidation state, making the atom more negative or less positive. The acronym OIL RIG (Oxidation Is Loss, Reduction Is Gain) can help remember this concept.

Step-by-step solution

1. Understanding Redox Reactions

Redox reactions, short for reduction-oxidation reactions, are chemical reactions in which the oxidation state (or number) of one or more elements changes. In these reactions, two key processes occur: reduction and oxidation. These two processes always happen simultaneously, with one substance being reduced while another is being oxidized.

2. Reduction and Oxidation

In a redox reaction, reduction refers to the process where a substance gains electrons, whereas oxidation is the process where a substance loses electrons. An easy way to remember this is by using the acronym OIL RIG: Oxidation Is Loss (of electrons), Reduction Is Gain (of electrons).

3. Origin of the Term "Reduced"

The term "reduced" in redox reactions has its origin in early chemistry, where reduction was thought to mean the removal of oxygen from a substance. As the understanding of chemistry developed, it was discovered that reduction actually involves a gain in electrons. However, the name "reduction" stuck because it still made sense in a different context: reduction of the oxidation state (or number).

4. What is Being Reduced?

When something gains electrons and we say it is "reduced," we are actually referring to its decrease in oxidation state. The oxidation state of an atom is a number assigned to the atom in a molecule that signifies the atom's apparent charge. By gaining electrons, the atom becomes more negative or less positive, which means its oxidation state has been reduced or decreased. In conclusion, when something gains electrons in a redox reaction, it is said to be reduced because its oxidation state has been decreased. The term "reduced" originates from the early understanding of the removal of oxygen from a substance but now refers to the gain of electrons and the decrease in an oxidation state.