Problem 9 - Biology: The Unity and Diversity of Life

Question

A molecule that donates electrons becomes _____ and the one that accepts electrons becomes ____. a. reduced; oxidized b. ionic; electrified c. oxidized; reduced d. electrified; ionic

Step-by-Step Solution

Answer

c. oxidized; reduced

Step 1: Understand the Basic Concept

In a chemical context, oxidation and reduction are key processes. Oxidation refers to the loss of electrons, while reduction refers to the gain of electrons. This is often remembered by the acronym 'OIL RIG' (Oxidation Is Loss, Reduction Is Gain).

Step 2: Identify the Process for Electron Donor

A molecule that donates electrons is undergoing oxidation because it is losing electrons in the process. It is referred to as 'oxidized.'

Step 3: Identify the Process for Electron Acceptor

A molecule that accepts electrons undergoes reduction because it is gaining electrons. It is referred to as 'reduced.'

Step 4: Match Definitions with Options

Given the possible answers, we need to identify oxidation and reduction as described. The correct phrase to fill the blanks is 'oxidized' for the electron donor and 'reduced' for the electron acceptor.

Key Concepts

Electron Donor

In chemical reactions, certain molecules play the role of donating electrons. When a molecule donates electrons, it is called an "electron donor." This process involves the transfer of electrons from the donor molecule to another molecule. When an electron donor releases its electrons, it undergoes a transformation known as oxidation.

• **Oxidation**: The electron donor loses electrons. This makes the donor "oxidized."
• **Positive Charge**: As electrons leave, the donor might have a more positive charge or less negative charge than before.

A simple way to remember what happens to electron donors is by using the acronym "OIL RIG," which stands for "Oxidation Is Loss" (of electrons). This helps in memorizing that losing electrons is the oxidation process.

Electron Acceptor

In the context of electron transfer, the "electron acceptor" is the counterpart to the donor. An electron acceptor is a molecule that receives electrons from another molecule, the electron donor. When an electron acceptor gains electrons, it undergoes a process called reduction.

• **Reduction**: The electron acceptor gains electrons, becoming "reduced."
• **Negative Charge**: By gaining electrons, the electron acceptor becomes more negatively charged or less positive.

This can be remembered easily using the same mnemonic device: "OIL RIG." Here, "Reduction Is Gain" of electrons. Electron acceptors are essential for balancing the charge and completing the reaction processes.

Oxidized and Reduced

The terms "oxidized" and "reduced" describe the state of molecules after electron transfer has occurred. These transformations involve the movement of electrons from one molecule to another.

• **Oxidized State**: When a molecule loses electrons, it is said to be "oxidized." This means it has less negative or more positive charge.
• **Reduced State**: Conversely, when a molecule gains electrons, it is "reduced," resulting in a higher negative charge or less positive charge.

Oxidation and reduction are linked processes; one cannot happen without the other. As a molecule becomes oxidized, another must be reduced. Understanding these states is crucial for mastering concepts related to chemical reactions and electron transfers.