Dispersion forces arise due to what?

Dispersion forces arise due to what?

• A. Permanent dipole alignment
• B. Momentary partial charges from moving electrons
• C. Ionic bonding
• D. Hydrogen bonding

Answer: (B)

Momentary partial charges from moving electrons drive dispersion forces. As electrons continually swirl around nuclei, the electron density in a molecule fluctuates, creating an instantaneous dipole. That temporary dipole can induce a dipole in a neighboring molecule, and the resulting attraction between these induced dipoles is the London dispersion force. The strength grows with the number of electrons and the molecule’s ease of polarizability, so larger or more electron-rich species exhibit stronger dispersion interactions. Permanent dipoles and their interactions arise from fixed charges, which is a different kind of attraction, while ionic bonding and hydrogen bonding are separate types of intermolecular forces.

Momentary partial charges from moving electrons drive dispersion forces. As electrons continually swirl around nuclei, the electron density in a molecule fluctuates, creating an instantaneous dipole. That temporary dipole can induce a dipole in a neighboring molecule, and the resulting attraction between these induced dipoles is the London dispersion force. The strength grows with the number of electrons and the molecule’s ease of polarizability, so larger or more electron-rich species exhibit stronger dispersion interactions. Permanent dipoles and their interactions arise from fixed charges, which is a different kind of attraction, while ionic bonding and hydrogen bonding are separate types of intermolecular forces.