Ionic compounds are held together by strong electrostatic forces between positively and negatively charged ions. These forces are stronger than the Van der Waals forces that hold together molecules in covalent compounds. Therefore, ionic compounds have higher melting points than covalent compounds.

The melting point of an ionic compound is the temperature at which the solid phase changes to the liquid phase. At this temperature, the kinetic energy of the ions is great enough to overcome the attractive forces between them and they can move past each other. The higher the melting point, the stronger the attractive forces between the ions.

The melting point of an ionic compound depends on a number of factors, including the charge of the ions, the size of the ions, and the lattice energy. The charge of the ions is the most important factor. The greater the charge of the ions, the stronger the attractive forces between them and the higher the melting point. The size of the ions also plays a role. The smaller the ions, the closer they can pack together and the stronger the attractive forces between them. This is why ionic compounds with small ions have higher melting points than ionic compounds with large ions. Finally, the lattice energy is also a factor. The lattice energy is the energy required to separate all the ions in a crystal lattice. The higher the lattice energy, the stronger the attractive forces between the ions and the higher the melting point.