Question #49b16

1 Answer
Jun 26, 2017


Here's my explanation.


#"NaCl"# has a cubic unit cell.

You can think of it as a face-centered cubic array of chloride ions with an interpenetrating sodium ion lattice.

(Adapted from

In the above diagram, there is a chloride atom at each corner and a sodium on in the centre of each edge.

The distance from the centre of a #"Cl"^"-"# ion to the centre of an #"Na"^"+"# ion takes us to the centre of an edge.

Thus, if the distance between the ions is X pm, the edge length is 2X pm.