Intermolecular Forces

Intermolecular forces, which exist between molecules, originate from electrostatic interactions between charges, partial charges, and temporary charges.

All molecules produce temporary charges. Due to the varying distribution of electrons, a higher electron density in one region of the electron cloud results in an instantaneous dipole, or a temporary dipole.

This subsequently induces another instantaneous dipole in the neighboring molecule. The domino effect of dipoles gives rise to weak intermolecular attractive forces called dispersion forces, which exist between all molecules, whether polar or nonpolar.

Some covalent compounds, like water, for example, exhibit electron-rich and electron-poor regions caused by the atoms’ differences in electronegativity.

The uneven distribution of shared electrons and the molecular shape of the compound create permanent partial charges, resulting in a permanent dipole in the otherwise neutral compound — making it polar.

Molecules with permanent dipoles — also called polar compounds — align themselves through dipole–dipole forces, where the positive end of one molecule interacts electrostatically with the negative end of the neighboring molecule.