Which force is a hydrogen-bonding interaction that occurs when a hydrogen atom is bonded to a highly electronegative atom?

• A. London dispersion forces
• B. Dipole
• C. Solvent
• D. Hydrogen bonding

Answer: (D)

Hydrogen bonding is a strong kind of dipole-dipole interaction that occurs when hydrogen is covalently bonded to a highly electronegative atom such as nitrogen, oxygen, or fluorine. That electronegative atom pulls electron density away from the hydrogen, giving the hydrogen a noticeable partial positive charge. Because of this positive hydrogen, it is attracted to lone pairs on a nearby electronegative atom in another molecule (or a different part of the same molecule), forming a hydrogen bond. This type of interaction is stronger than typical dipole-dipole forces and much stronger than London dispersion forces, yet it remains distinct from a covalent bond. For example, in water, the H from one molecule forms hydrogen bonds with the O lone pairs of neighboring water molecules, which helps explain water’s high boiling point and many of its unusual properties. Solvent describes a medium, not a specific attractive force, and London dispersion forces or a general dipole refer to weaker or more generic interactions, respectively.