What characteristic makes a solution different from a colloid?

A solution is distinguished from a colloid primarily by particle size. In a solution, the solute particles are completely dissolved in the solvent and exist at a molecular or ionic level, typically with diameters less than 1 nanometer. This small size allows the particles to remain evenly distributed throughout the solvent, resulting in a clear and transparent appearance.

On the other hand, in a colloid, the particles are larger, typically in the range of 1 nanometer to 1 micrometer. These larger particles do not settle out over time and can scatter light, which is why colloids often appear cloudy or opaque. The difference in particle size is the key factor that differentiates these two types of mixtures, influencing their physical properties and behavior in various environments.

Understanding the nature of particle size helps in analyzing how substances interact in different scenarios, such as in biological systems or industrial applications, where the properties of solutions and colloids can lead to varying outcomes based on their characteristics.