Which intermolecular force exists among noble gas atoms and nonpolar molecules due to instantaneous dipoles?

• A. Dipole-dipole
• B. Ionic
• C. London dispersion
• D. Hydrogen bonding

Answer: (C)

Instantaneous dipoles producing temporary attractions between particles are London dispersion forces. Even though noble gas atoms and nonpolar molecules don’t have permanent dipoles, the electrons are always moving. This movement can create a momentary uneven distribution of charge, an instantaneous dipole. That temporary dipole can induce a dipole in a neighboring particle, and the two attract each other briefly. That weak attraction is the London dispersion force, and it’s the only significant intermolecular force in noble gases and nonpolar species under many conditions. These forces are weaker than hydrogen bonds or ionic interactions, but they’re universal and become stronger as the atoms or molecules become larger or more polarizable. The other options don’t fit because dipole-dipole requires a permanent dipole, ionic involves full charge transfer, and hydrogen bonding needs a hydrogen attached to F, O, or N.