Which intermolecular force arises when polar molecules align so that positive and negative ends are near each other?

Which intermolecular force arises when polar molecules align so that positive and negative ends are near each other?

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

Answer: (B)

Polar molecules have regions of partial positive and partial negative charges, so the interactions between them come from electrostatic attractions of those opposite ends. When two polar molecules orient so that the positive end of one is near the negative end of the other, they pull on each other through dipole-dipole interactions. This type of force is the common attraction between most polar liquids and solids, and it explains why polarity often leads to higher boiling points compared to nonpolar substances of similar size. Hydrogen bonding is a stronger, specific kind of dipole-dipole interaction that occurs only when hydrogen is bonded to highly electronegative atoms like nitrogen, oxygen, or fluorine and can interact with lone pairs on another molecule. London dispersion forces are present in all molecules, including nonpolar ones, but they are typically weaker than dipole-dipole interactions for polar species. Ionic forces involve full charges and belong to salts rather than neutral polar molecules.

Polar molecules have regions of partial positive and partial negative charges, so the interactions between them come from electrostatic attractions of those opposite ends. When two polar molecules orient so that the positive end of one is near the negative end of the other, they pull on each other through dipole-dipole interactions. This type of force is the common attraction between most polar liquids and solids, and it explains why polarity often leads to higher boiling points compared to nonpolar substances of similar size.

Hydrogen bonding is a stronger, specific kind of dipole-dipole interaction that occurs only when hydrogen is bonded to highly electronegative atoms like nitrogen, oxygen, or fluorine and can interact with lone pairs on another molecule. London dispersion forces are present in all molecules, including nonpolar ones, but they are typically weaker than dipole-dipole interactions for polar species. Ionic forces involve full charges and belong to salts rather than neutral polar molecules.