What distinguishes hydrophobic molecules?

Hydrophobic molecules are characterized by their non-polar nature, which means they lack distinct positive and negative charges. This property prevents them from forming strong interactions with water molecules. As a result, hydrophobic molecules do not dissolve in water; instead, they tend to aggregate together to minimize their exposure to water. This behavior is crucial in biological systems, such as in the formation of cell membranes, where hydrophobic tails of phospholipids create a barrier that separates the interior of the cell from the aqueous environment.

In contrast, hydrophilic molecules, which readily dissolve in water, have polar or charged regions that can interact favorably with water molecules. The presence of ionic bonds typically indicates strong interactions with water, which doesn't align with the characteristics of hydrophobic molecules. Moreover, the ability to absorb water implies a compatibility with water that hydrophobic molecules lack. Thus, the defining feature of hydrophobic molecules is their non-polar composition and resulting inability to dissolve in water.