Which of the following intermolecular forces is the weakest?

• A. Ion-dipole interactions
• B. Hydrogen bonding
• C. Dipole-dipole interactions
• D. London dispersion forces

Answer: (D)

Verified step by step guidance

1. Understand the types of intermolecular forces: Ion-dipole interactions occur between an ion and a polar molecule, hydrogen bonding is a strong type of dipole-dipole interaction involving hydrogen and electronegative atoms like oxygen, nitrogen, or fluorine, dipole-dipole interactions occur between polar molecules, and London dispersion forces are weak forces present in all molecules, especially nonpolar ones.
2. Recognize that London dispersion forces arise due to temporary fluctuations in electron density, leading to temporary dipoles that induce dipoles in neighboring molecules.
3. Compare the relative strengths of these forces: Ion-dipole interactions are generally the strongest due to the full charge of ions interacting with dipoles. Hydrogen bonds are strong due to the specific interaction between hydrogen and electronegative atoms. Dipole-dipole interactions are weaker than hydrogen bonds but stronger than London dispersion forces.
4. Identify that London dispersion forces are the weakest because they are temporary and arise from momentary dipoles, whereas the other forces involve permanent dipoles or specific interactions.
5. Conclude that among the given options, London dispersion forces are the weakest intermolecular forces.