[pnicogen1]

I a CsCl lattice, the atoms usually touch along the diagonal from corner through the center of the cell to the opposite corners. If the ionic radii are R+ and R-, calculated the length of each side of the unit cell.

I don't know how to solve this because on the sides of a CsCl the anions are touching...so how do I calculate the side length?

[UG]

This question requires a bit of trigonometry, since the atoms are touching along the diagonals, what is the length of the diagonal? How can you relate the length of the diagonal with the length of the side?

[pnicogen1]

Ahh, so I figured it out. So the diagonal of the CsCl structure is where the anion and cation touch. I just gave the edge length a variable, x. The diagonal on the plane of the unit cell is sqrt(2)x; I just used pythagorean theorem x^2+(sqrt(2)x)^2= (2radiusanionic+2radiuscationic)^2 and came up with my answer:

edge length (x)= 1.15(radius anionic + radius cationic)

[UG]

Yup I got that answer too.

[pnicogen1]

Thanks a lot!