amphiphilicity

Amphiphilicity refers to a molecule's ability to have both water-attracting (hydrophilic) and water-repelling (hydrophobic) parts. This dual nature enables such molecules to interact with different environments—for example, they can dissolve at the boundary between water and oil. A common example is soap, which has a hydrophilic head that binds with water and a hydrophobic tail that attaches to grease or oil. This property is essential in many biological processes, like forming cell membranes, where the molecules arrange themselves to create a barrier that separates the inside of the cell from its surroundings.