# In ionic solids such as NaCl, do the cations fill interstital holes in the cation's cubic close pack structure? [duplicate]

Are binary ionic solids like $\ce{NaCl}$ comprised of a cubic close packed structure of the anions with the cations filling interstital holes or do the cations and the anions contribute to the cubic close packed structure equally? I am really struggling with solid state chemistry - any help would be gratefully received. Also any suggestions for good learning resources on this topic would be great. Thanks.

• This might be helpful. When we talk about close packed structures, we're really only describing the positions of atoms relative to one another, not their bonding and there are often multiple equivalent ways to think about them, though which ions are involved do of course influence which crystal structures are stable. – Michael DM Dryden Feb 3 '15 at 21:39