Ion-dipole forces are inter-molecular forces that occur between an ion and a polar molecule. An ion is an atom or group of atoms that holds an electrical charge, while a dipole refers to a molecule that possesses a delocalized positive and negative charge. Ion-dipole forces, therefore, are the electrostatic interactions between the fixed dipole in one molecule and an ion.
An ion-dipole force is a type of intermolecular force in which forces of attraction or repulsion occur between neighboring ions, molecules or atoms. The ion-dipole force results from the attraction of an ion of negative or positive charge and the oppositely charged end of the dipole molecule.
In addition to ion-dipole forces, there are three other types of attractive intermolecular forces: dipole-dipole forces; dipole-induced dipole forces; and instantaneous dipole-induced dipole forces. Ion-dipole forces operate much like induced-dipole and dipole-dipole interactions. However, ion-dipole forces possess ions instead of non-polar or polar molecules. An ion has a far greater charge than a dipole, which explains why ion-dipole forces are much stronger than dipole interactions.
Ion-dipole forces involve the interaction between an ion and a polar molecule. The molecules align so that the positive and negative forces are side by side allowing for maximum bonding.