posted by Cathy .
I need help with getting started:
1.The crystal structure of an ionic compound consists of alternating cations and anions lying next to each other in three dimensions. If the cation radius is 55.1% of the anion radius and the distance between the cation nuclei is 587 pm, what are the radii of the two ions? (Note: This ionic compound is a three dimensional array. The cation to cation, center-to-center distance specified is through the center of the anion.)