During column chromatography, what factor primarily affects the separation of compounds?

In column chromatography, the primary factor that affects the separation of compounds is the polarity of the compounds. This technique relies on the different affinities of compounds for the stationary phase (usually a polar substance like silica gel) versus the mobile phase (a solvent that can vary in polarity).

When a mixture is passed through the column, more polar compounds tend to interact more strongly with the stationary phase and thus move more slowly through the column. In contrast, less polar compounds have a weaker interaction with the stationary phase and travel faster through the column. This differential interaction based on polarity allows for the effective separation of compounds as they elute at different times.

While boiling point, size, and shape of compounds can influence aspects of chromatography, such as their solubility or how they interact with solvents, the primary mechanism that dictates separation in column chromatography is the difference in polarity between the compounds being separated.