Final answer:
NaCl is expected to have a higher melting point than CsCl because of its stronger Coulombic interactions and the stronger ionic bonds due to the smaller size and higher charge of the Na+ ions.
Step-by-step explanation:
Between sodium chloride (NaCl) and cesium chloride (CsCl), NaCl is expected to have a higher melting point due to its stronger Coulombic interactions. The ions within NaCl (with a lattice energy of 876 kJ/mol) have a higher charge density compared to those in CsCl, because the Na+ ions are smaller and have a greater ability to polarize the electron cloud of the Cl- ions. This results in stronger ionic bonds and thus a higher melting point for NaCl. Additionally, NaCl forms a different crystal lattice structure compared to CsCl due to size differences of the cations, which also influences the melting points.
The melting points are influenced by the strength of the intermolecular forces holding the ions in place. Ionic solids like NaCl and CsCl are held together by ionic bonds, which are significantly stronger than the other types of intermolecular forces like hydrogen bonds or Van der Waals forces present in molecular compounds. Since the melting point is dependent on the strength of these attractive forces, and since NaCl has stronger ionic bonding due to the smaller size and higher charge of Na+ compared to Cs+, NaCl has a higher melting point than CsCl.