Intermolecular forces in NaCl involve strong electrostatic interactions between the positively charged sodium ions (Na+) and negatively charged chloride ions (Cl-), resulting in ionic bonding. These forces are non-directional and long-range, creating a crystalline lattice structure with a face-centered cubic arrangement. The high melting and boiling points, crystalline structure, and brittleness of NaCl demonstrate the strength of these intermolecular forces.