Sorting Lattice Energies: KF, MgS, RbI

[cdoss]

Homework Statement

Place the following in order of decreasing magnitude of lattice energy.

KF, MgS, RbI

I'm not really sure how to do this without looking up the lattice energy values with each. And I don't think that is what our teacher wants us to do

 

[Borek]

Think just in terms of charges and radii of the ions. This is about simple Coulomb forces.