In the ionic compounds LiF,NaCl, KBr, and RbI, the measured cation-anion distances are 2.01 Å (Li-F), 2.82 Å (Na-Cl), 3.30 Å (K-Br), and 3.67 Å (Rb-I), respectively.
(a) Predict the cation-anion distance using the values of ionic radii given in Figure.
(b) Calculate the difference between the experimentally measured ion-ion distances and the ones predicted from Figure. Assuming we have an accuracy of 0.04 Å in the measurement, would you say that the two sets of ion-ion distances are the same or not?
(c) What estimates of the cation-anion distance would you obtain for these four compounds using bonding atomic radii? Are these estimates as accurate as the estimates using ionic radii?
