1. The problem statement, all variables and given/known data Calculate the Madelung constant for an octahedral arrangement of doubly charged anions about a doubly charged cation. Use r0 for the anion−cation distance. (Hint: Remember that the Madelung constant considers the sum of Coulomb interactions over all atom/ion pairs). 2. Relevant equations Possibly helpful Equations EA=-(Mke2)/r0 α=2M/((n1+n2)|Z1Z2|) EA=-(ke2α(n1+n2(|Z1Z2)/2r0 3. The attempt at a solution So we have a theoretical bond pair X+2Y-2 with a coordination number of 6. I believe the next step should be to calculate EA, but I fail to see how to do that with out α.