Why do ionic compounds tend to have high melting points?
Ionic compounds are formed by ions: cations and anions. A cation is formed when an atom loses an electron/s and an anion is formed when an atom gains one or more electron/s. An example of an ionic compound is sodium chloride, which is formed between a sodium cation (Na+) and chloride anion (Cl-).
Compounds formed through an exchange of electrons (between ions) have stronger bonds as compared to covalent compounds. The ionic compounds are held together by electrostatic forces which are very strong. In the case of covalent compounds, atoms are held together by weak intermolecular forces. The stronger the bond, the higher the energy needed to break them. Thus, the ionic compounds have higher melting and boiling points as compared to covalent compounds.
The strong intermolecular attraction is also the reason ionic compounds are mostly solid at room temperature. This is directly correlated to their high melting points.
Hope this helps.