What is the coordination number of Na^ + and Cl^ - ions in NaCl...

In the NaCl (sodium chloride) crystal lattice, each sodium ion $\left(\mathrm{Na}^{+}\right)$is surrounded by 6 chloride ions ( $\mathrm{Cl}^{-}$), and each chloride ion is surrounded by 6 sodium ions. This arrangement is known as a face-centered cubic (FCC) structure, where each ion is in contact with 6 nearest neighbours in all directions. This high coordination number of 6 ensures strong electrostatic interactions between ions, contributing to the stability of the crystal lattice and the characteristic properties of NaCl .