What physical property determines the strength of intermolecular forces?

• A. Molecular mass
• B. Molecular polarity
• C. Atomic radius
• D. Electronegativity

Answer: (B)

The strength of intermolecular forces is primarily determined by molecular polarity. Polar molecules have a distribution of charge due to differences in electronegativity between the atoms involved, leading to partial positive and negative charges. This charge separation results in dipole interactions, which can significantly enhance attractive forces between molecules.

In polar molecules, the orientation of these dipoles can lead to stronger dipole-dipole interactions or hydrogen bonding, especially if hydrogen is bonded to highly electronegative atoms such as nitrogen, oxygen, or fluorine. These forces are much stronger than those found in nonpolar molecules, where the intermolecular forces are typically limited to London dispersion forces, which arise from temporary fluctuations in electron distribution.

While molecular mass, atomic radius, and electronegativity can all influence properties like boiling points and solubility, they are not the primary factors dictating the strength of intermolecular forces like molecular polarity does. Molecular mass can affect the strength of dispersion forces, but it is not directly related to the nature of the intermolecular forces in polar molecules. Atomic radius generally pertains to the size of the atoms involved and thus not directly to the intermolecular forces. Electronegativity is important for establishing polarity, but it’s the resulting polarity that mainly defines