In the sodium chloride structure, each ${\mathrm{Na}}^{+}$ ion i surrounded by six ${\mathrm{Cl}}^{-}$ ions nearest neighbours and .......... ${\mathrm{Na}}^{+}$ ions next nearest neighbour.

Each ${\mathrm{Na}}^{+}$ ion in the sodium chloride structure has the following neighbours: r is the distance between ${\mathrm{Na}}^{+}$ and Cl-, and there are six ${\mathrm{Cl}}^{-}$ at this distance. Eight ${\mathrm{Cl}}^{-}$ are located at a distance of $\sqrt{3} \mathrm{r}$ and are the third closest neighbours, followed by twelve ${\mathrm{Na}}^{+}$ at a distance of $\sqrt{2} \mathrm{r}$.