What is the Difference Between Ionic and Molecular Solids?

Ionic and molecular solids are two different types of solid substances with distinct properties and characteristics. The main differences between them include:

1. Constituent particles: Ionic solids are composed of charged ions (cations and anions), while molecular solids consist of monoatomic or polyatomic molecules.
2. Bonding: Ionic solids have ionic bonds, where electrons are transferred between atoms, resulting in positive and negative ions held together by electrostatic forces. In contrast, molecular solids have mainly Van der Waals forces, and there can be hydrogen bonds or other weak chemical interactions between molecules.
3. Melting and boiling points: Ionic solids typically have high melting and boiling points due to the strong electrostatic forces holding the ions together. Molecular solids, on the other hand, have low melting and boiling points because of the weak intermolecular forces between the molecules.
4. Hardness and brittleness: Ionic solids are generally hard and brittle, while molecular solids are relatively soft.
5. Electrical conductivity: Ionic solids can conduct electricity when molten or dissolved in water due to the movement of ions. Molecular solids, however, are poor conductors of electricity.

Some examples of ionic solids include sodium chloride (NaCl) and calcium fluoride (CaF2), while examples of molecular solids include ice and benzoic acid.

Comparative Table: Ionic vs Molecular Solids

Here is a table summarizing the differences between ionic and molecular solids:

Ionic solids are composed of cations and anions held together by electrostatic attraction forces, while molecular solids are composed of neutral molecules held together by weak intermolecular forces. Ionic solids typically have high melting points and are solids at room temperature, whereas molecular solids can be gases, liquids, or solids and have lower melting points. Ionic solids are generally soluble in water and conduct electricity well when molten or in solution, while molecular solids have variable water solubility and poor electrical conductivity.