Molecules that do not interact with water are known as?

Molecules that do not interact with water are known as hydrophobic. Hydrophobic molecules are typically nonpolar, meaning they do not have a charge separation within the molecule that would allow them to form interactions with polar molecules like water. Because of their lack of affinity for water, hydrophobic substances tend to aggregate together in aqueous environments to minimize their exposure to water. This behavior is crucial in biological systems, especially in the formation of cell membranes, where hydrophobic tails of phospholipids face inward, away from water, while hydrophilic heads orient outward towards the aqueous environment.

In contrast, hydrophilic molecules have polar regions that allow them to interact and dissolve in water, making them quite different from hydrophobic substances. Amphipathic molecules possess both hydrophilic and hydrophobic regions, which enables them to interact with both water and nonpolar substances. Polar molecules have an uneven distribution of charge, leading them to interact favorably with water due to their ability to form hydrogen bonds. Understanding these distinctions is key to grasping how different types of molecules behave in biological systems and environments.