* Definition: A solute is the substance that dissolves in a solvent to form a solution. The solvent is the substance that does the dissolving.

* Dissolving: The process of dissolving involves the solute particles being surrounded and separated by the solvent particles. For this to happen effectively, the solvent molecules need to be able to interact with the solute molecules.

* Size Matters: If the solute molecules are significantly larger than the solvent molecules, the solvent molecules won't be able to effectively surround and separate the solute. This would make it difficult for the solute to dissolve.

Example: Imagine trying to dissolve a large rock in a small cup of water. The rock particles are much larger than the water molecules, and the water molecules won't be able to break down the rock into smaller pieces.

Key Point: While the solute can be present in a smaller *quantity* than the solvent, its individual molecules cannot be larger than the individual molecules of the solvent.