In a CsCl-type crystal the radii of the cation and anion are $169 pm$ and $181 pm$ , and ions touch along the body diagonal. With $3 = 1.732$ , calculate the unit cell edge in pm (nearest integer).

Numerical answer type, answer in pm, tolerance 1.

Answer: 404 pm

Body diagonal

= 3 a = 2 (r_{+} + r_{-}) = 700 pm

a = \frac{700}{1.732} = 404.16 pm \approx 404 pm