Intermolecular Forces and Physical Properties

Electrostatic interactions that exist between molecules are called intermolecular forces. These attractive forces influence various physical properties, such as melting point, boiling point, and solubility.

The three major types of intermolecular forces include strong ion–dipole interactions between ions and polar molecules, dipole–dipole interactions between polar molecules, and finally, the weakest of all — dispersion forces — present in all molecules, polar and nonpolar.

Ion–dipole interactions are common to solutions. When an ionic compound like sodium chloride is dissolved in a polar solvent like water, the ions align with the oppositely charged ends of the water molecules, allowing maximum electrostatic attraction.

Alternatively, dipole–dipole interactions are exhibited by polar molecules with permanent dipoles, where the positive end of one molecule interacts electrostatically with the negative end of the neighboring molecule.

When a hydrogen atom bonded to either oxygen, nitrogen, or fluorine is attracted to the electronegative atom of a neighboring molecule, a hydrogen bond — a special type of dipole–dipole interaction — is formed. Notably, compounds capable of hydrogen bo