NaCl crystal structure can be thought of in the following way:

  •   The chlorine anions (green) form a face centered cubic close-packing structure

  •   The sodium cations (blue) fit into the octahedral spaces formed by the chlorine.

  • Note that there are 6 atoms (green) around every hole (blue) but also 6 holes around every atom. So, the ration atoms : holes = 1 : 1.

  • the cube itself is highlighted by 8 interconnected small silver balls (inside the green atoms).

 

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