Final answer:
Dispersion forces are temporary electrostatic attractions that arise from the random electronic motion within all substances, causing a temporary dipole that can induce a dipole in a neighboring atom or molecule, resulting in a brief attraction.
Step-by-step explanation:
Dispersion forces are temporary electrostatic attractions that occur due to the random electronic motion within all substances, including those that are nonpolar. When the electrons within a molecule or atom are distributed asymmetrically about the nucleus, that molecule or atom will adopt a temporary, instantaneous dipole. The presence of this dipole can then distort the electrons of a neighboring atom or molecule, producing an induced dipole. These two rapidly fluctuating dipoles thus result in a brief electrostatic attraction between the two species. These forces are stronger in larger atoms and molecules. For example, dispersion forces between iodine molecules will be stronger than dispersion forces between fluorine molecules because iodine has more electrons, leading to stronger interactions.