Which statement best describes Van der Waals interactions?

• A. They are stronger than ionic bonds
• B. They occur only within molecules
• C. They are physical bonds between all atoms and are the weakest
• D. They involve electron transfer

Answer: (C)

Van der Waals interactions are weak, non-covalent forces that arise from fluctuations in electron distribution. They come from temporary dipoles in one part of a molecule or on one molecule, which induce dipoles in neighboring parts or molecules, producing a tiny attraction. Because they are not chemical bonds, they don’t involve sharing or transferring electrons; they’re physical interactions that exist between all atoms and molecules, and they are the weakest of the common intermolecular forces.

This is why they’re described as the weakest, and why they’re not like ionic or covalent bonds. They can occur between molecules (and even between parts of large molecules), and their strength generally increases with molecular size and polarizability. The other statements either mischaracterize the nature (they’re not electron transfer) or the scope (not only within molecules, and not true bonds).