Ionic compounds generally have much higher melting points compared to molecular compounds. This difference in melting points can be attributed to the nature of the bonds that hold the atoms and molecules together.
Ionic compounds are made up of positively and negatively charged ions. The strong electrostatic forces of attraction between these oppositely charged ions create a robust ionic bond, resulting in a solid structure that requires a significant amount of energy to break apart when heated. As a result, ionic compounds typically melt at high temperatures, often above 300°C.
On the other hand, molecular compounds are composed of molecules held together by weaker intermolecular forces, such as Van der Waals forces or hydrogen bonds. These forces are significantly weaker than ionic bonds, so less energy is needed to overcome them. Consequently, molecular compounds tend to have lower melting points, with many melting at temperatures below 100°C.
In summary, the contrasting melting points of ionic and molecular compounds stem from the differences in the strength of the bonds that form their structures. Ionic compounds’ strong ionic bonds lead to high melting points, while the weaker intermolecular forces in molecular compounds result in lower melting points.