Ionic compounds are characterized by a crystalline structure composed of positively and negatively charged ions held together by strong electrostatic forces. These compounds form through the transfer of electrons from metal atoms (cation) to non-metal atoms (anion), resulting in the creation of oppositely charged ions. The ionic bonds between these ions create a stable lattice structure with high melting and boiling points. Ionic compounds are typically solid at room temperature, have good electrical conductivity when molten or dissolved in water, and exhibit brittle behavior due to the arrangement of ions in a rigid lattice. They often display high solubility in water.