The diagram that follows represents a molecular view of a process occurring at an electrode in a voltaic cell.

(c) Why are the atoms in the electrode represented by larger spheres than those in the solution? [Section 20.3]

Verified step by step guidance

1. Step 1: Identify the components in the diagram. The larger spheres represent atoms in the electrode, while the smaller spheres represent ions in the solution.
2. Step 2: Understand the context of a voltaic cell. In a voltaic cell, oxidation and reduction reactions occur at the electrodes, leading to the transfer of electrons and ions.
3. Step 3: Recognize that the larger spheres in the electrode are atoms in their metallic form, which are typically larger due to the presence of a full set of electrons and a neutral charge.
4. Step 4: Note that the smaller spheres in the solution are ions, which are smaller because they have lost or gained electrons, resulting in a change in size due to the ionic charge and the loss of electron cloud.
5. Step 5: Conclude that the difference in size between the atoms in the electrode and the ions in the solution is due to the difference in their physical states and charges, with neutral atoms being larger and charged ions being smaller.

Key Concepts

Atomic Size and Representation

In molecular diagrams, the size of spheres often represents the relative size of atoms or ions. Larger spheres typically indicate atoms that are part of a solid structure, such as those in an electrode, while smaller spheres represent ions in solution. This visual distinction helps convey the difference in density and arrangement between solid and liquid phases.

Electrode Function in Voltaic Cells

In a voltaic cell, electrodes serve as sites for oxidation and reduction reactions. The electrode is where electrons are transferred, and the larger spheres represent the solid metal atoms that facilitate this process. Understanding the role of electrodes is crucial for grasping how voltaic cells generate electrical energy through chemical reactions.

Phase Differences in Matter

The concept of phases in matter—solid, liquid, and gas—explains the differences in atomic arrangement and behavior. In solids, atoms are closely packed in a fixed structure, while in liquids, they are more dispersed and mobile. This distinction is essential for understanding why the electrode atoms appear larger and more organized compared to the smaller, more dynamic ions in solution.