Question

What type of close-packing is possessed by a crystal of NaCl?

Answer 1

In the crystal structure of sodium chloride (NaCl), the chloride ions (Cl⁻) form a cubic close-packed (ccp) or face-centred cubic (fcc) arrangement. The sodium ions (Na⁺) occupy the octahedral voids created by the close-packed Cl⁻ ions. Both Na⁺ and Cl⁻ ions have a coordination number of 6, meaning each ion is surrounded by six oppositely charged ions.