Final answer:
Van der Waals forces include dipole-dipole interactions, dipole-induced dipole interactions, and London dispersion forces. Dipole-dipole interactions occur between polar molecules, dipole-induced dipole interactions occur between a polar and a nonpolar molecule, and London dispersion forces occur between nonpolar molecules.
Step-by-step explanation:
Van der Waals forces are intermolecular forces that include dipole-dipole interactions, dipole-induced dipole interactions, and London dispersion forces.
Dipole-dipole interactions occur between polar molecules. These molecules have a permanent dipole moment due to the uneven distribution of electron density. The positive end of one molecule is attracted to the negative end of another molecule, creating an intermolecular force.
Dipole-induced dipole interactions occur between a polar molecule and a nonpolar molecule. The polar molecule induces a temporary dipole moment in the nonpolar molecule by repolarizing its electron cloud. This results in a weak intermolecular force.
Fluctuating dipoles, also known as London dispersion forces, occur between nonpolar molecules. These molecules have temporary, instantaneous dipole moments due to fluctuations in the distribution of electron density. These temporary dipoles induce dipole moments in neighboring molecules, resulting in weak attractive forces.