By Drew Lichtenstein Updated Mar 24, 2022
A compound is a substance formed by combining two or more distinct atoms. When those atoms are held together by the electrostatic attraction between oppositely charged ions, the resulting material is an ionic compound.
Ionic compounds consist of at least one metal and one nonmetal. An ion is formed when an atom loses or gains electrons, acquiring a positive or negative charge. The ionic bond is a powerful attraction between these charged species.
Due to their strong ionic bonds, these materials are solid under ordinary conditions. They exhibit a rigid lattice structure, which accounts for their high melting and boiling points. A familiar example is table salt (NaCl), which crystallizes into a cubic lattice of Na⁺ and Cl⁻ ions. While ionic compounds are often soluble in water, solubility does not alter their solid state.
Many ionic solids display metal‑like properties: they reflect light (luster), have high densities, and conduct heat and electricity when molten or dissolved, though their solid-state conductivity is comparatively low.
The energy that holds ions together in the lattice is called lattice energy. This robust bond makes ionic compounds resistant to change, resulting in melting points that can reach several hundred degrees Celsius and boiling points far above those of covalent molecules.
Understanding these attributes—solid structure, metallic traits, and strong ionic bonding—provides insight into why ionic compounds behave the way they do in everyday chemistry.
