Ionic compounds have high melting points because they are held together by strong electrostatic forces between oppositely charged ions. Breaking these strong attractions requires a significant amount of energy, leading to the need for high temperatures to melt the compound.
Elaboration:
Strong Electrostatic Forces:
Ionic compounds are formed when metals transfer electrons to nonmetals, resulting in positively charged cations and negatively charged anions. These oppositely charged ions are strongly attracted to each other, forming a crystal lattice structure.
Energy to Break Bonds:
To melt an ionic compound, the energy must be sufficient to overcome these strong electrostatic attractions and break the bonds holding the ions together in the crystal lattice. This energy is manifested as heat, which is why ionic compounds require high temperatures to melt.
High Melting Points:
The strong ionic bonds require a lot of energy to break, resulting in high melting points compared to compounds with weaker intermolecular forces, such as covalent compounds.