5. (20 pts) Upload a computer generated chart (not hand-drawn) for 5(a). For an ion pair X2+ -- Y1- , attractive and repulsive energies EA and ER, respectively, depend on the distance between the ions, a, according to ! = 3.72 " = 7.54 10#$ % For these expressions, energies are expressed in electron volts per ion pair, and a is the distance in nanometers. The net energy EN is just the sum of the preceding two expressions.

a. Superimpose on a single plot EN, ER, and EA for 0.15nm < a < 1.0 nm NOTE: This may be done in excel or other suitable program, use an appropriate increment step for a such that the critical features of the curves are clearly shown. Make sure that your chart is adequately labeled and completely legible.

b. On the basis of this plot, determine (3 pts). The equilibrium spacing r0 between the X2+ and Y1- ions. The magnitude of the bonding energy E0 between the two ions.

c. Using the data from part (b) along with the data in the table found at http://www.wiredchemist.com/chemistry/data/metallic-radii, determine which real compound from those listed in Table 2.3 from your text book (copied here) is represented by the X2+ - Y1- ionic pair. NOTE: your numbers are not likely to be exactly the same as those listed in these tables. Select the substance that is most likely for the information provided and your calculated values. Support your answer. (5 pts)