AI Tutor
Table salt (NaClNaCl) melts at a blistering 801∘C801^\circ\text{C}, even though it is made of a metal soft enough to slice with a butter knife and a toxic green gas. What invisible force locks these atoms together so tightly?
The answer lies in electron transfer, where atoms trade valence electrons to achieve stable, full outer shells.
When a neutral sodium atom loses its single valence electron, it becomes a positively charged cation (Na+Na^+), while a chlorine atom gains that electron to become a negatively charged anion (Cl−Cl^-).
Once formed, these opposite charges attract each other through electrostatic forces, creating an ionic bond.
Do sodium and chloride ions simply float around in isolated pairs like tiny dumbbells?

The Crystal Lattice

Instead of isolated pairs, millions of ions snap together into a continuous, alternating 3D grid called a crystal lattice.
In this structure, every single cation is surrounded by multiple anions, maximizing attractions while minimizing like-charge repulsions.
How do chemists measure the sheer strength holding this entire 3D crystal together?

Lattice Energy and Coulomb's Law

Lattice energy is the energy released when separated gaseous ions pack together to form one mole of a solid ionic crystal.