# Sodium ions bond with chlorine ions to form table salt, NaCl. Why does one sodium ion bond with one chlorine ion?

And of course, in an ionic solid (say $\text{sodium chloride}$), an isolated cation, a sodium ion, is BOUND ELECTROSTATICALLY to EVERY OTHER CHLORIDE ANION in the lattice. The attraction/repulsion follows $\text{Coulomb's Law}$, and is thus strongest between a close-packed ion, and (typically) its six nearest $C {l}^{-}$ neighbours. Such ionic bonding is believed to be responsible for the properties of many ionic solids: high melting point; crystallinity, hardness, and brittleness; lack of electrical conductivity in the SOLID state (but not in the liquid state or in solution).