Yes, van der Waals forces can occur in polar molecules. Van der Waals forces are a type of intermolecular force that arises due to temporary fluctuations in electron distribution within molecules. They are responsible for the attractions and repulsions between molecules.
Van der Waals forces can be divided into three types: dipole-dipole interactions, London dispersion forces, and hydrogen bonding.
Dipole-dipole interactions occur between polar molecules that have a permanent dipole moment. A dipole moment arises when there is an electronegativity difference between atoms within a molecule, causing an uneven distribution of electron density. The positive end of one molecule is attracted to the negative end of another, resulting in dipole-dipole interactions.
London dispersion forces, on the other hand, occur between all molecules, regardless of polarity. They arise due to temporary fluctuations in electron distribution, creating temporary dipoles within nonpolar molecules. These temporary dipoles induce dipoles in neighboring molecules, resulting in attractive forces.
Hydrogen bonding is a special type of dipole-dipole interaction that occurs specifically when hydrogen is bonded to a highly electronegative atom such as oxygen, nitrogen, or fluorine. The hydrogen atom in one molecule forms a weak bond with the electronegative atom in another molecule, leading to stronger intermolecular forces.
So, while van der Waals forces are particularly important in nonpolar molecules due to London dispersion forces, they can also occur in polar molecules through dipole-dipole interactions and hydrogen bonding.