IIA $2.$ Calculate the net number of $N{a}^{1+}$ and $C{l}^{1-}$ ions belonging to this cell.

$N{a}^{1+}$

$C{l}^1$

SHOW WORK:

$3.$ What is the ratio of positive to negative ions in a unit cell of NaCl $?$

Is this expected? Explain.

$4.$ What are the coordination numbers of the $N{a}^{1+}$ and $C{l}^{1-}$ ions? $($How many $N{a}^{1+}$ ions are around each $C{l}^{+}$ion, and vice versa?$)$

$N{a}^{14}$

$C{l}^{1-}$

Calculate the shortest distance between two $N{a}^{1+}$ ions and the shortest distance between two $C{l}^{1-}$ ions in terms of the unit cell edge length $(a_0).$

$N{a}^{1-1}$

$C{l}^{1-}$

Now build the NaCl unit cell by placing the sodium ions at the positions of the face$-$centered cubic unit structure, and the chloride ions in the "holes". $($Essentially$,$ this switches the positions of the $N{a}^{1+}$ and $C{l}^{1-}$ ions.$)$ What translation along the body diagonal $(d_b)$ of this cell would interchange the positions of the $N{a}^{1+}$ and $C{l}^{1-}$ ions?