Why don’t oil and water mix?

Oil and water don't mix because they have different molecular properties. Water is a polar molecule, with an uneven distribution of charge that results in a positive and negative end. Oil, on the other hand, is a nonpolar molecule, with an even distribution of charge. Like dissolves like, and since water is polar while oil is nonpolar, they are immiscible.

When you try to mix them, water molecules attract and bond with other water molecules, forming a network of hydrogen bonds. Oil molecules, however, prefer to cluster together due to their nonpolar nature, creating a separate phase. This immiscibility results in the familiar separation of oil and water layers, which is a fundamental principle in chemistry and the reason why these two substances do not readily combine.