Question

Examine the trends in lattice energy in Table 12.1. The value of the lattice energy becomes somewhat more negative on going from NaI to NaBr to NaCl, and all are in the range from -700 to -800 kJ/mol. What is one reason why that the lattice energy of NaF which is -926 kJ/mol is much more negative than those of the other sodium halides?

Table 12.1

Lattice Energies of Some Ionic Compounds

Compound	(kJ/mol)
LiF	-1037
LiCl	-852
LiBr	-815
LiI	-761
NaF	-926
NaCl	-786
NaBr	-752
NaI	-702
KF	-821
KCl	-717
KBr	-689
KI	-649