Think of forming an ionic compound as three steps (this is a simplification, as with all models):
(1) Removing an electron from the metal
(2) Adding an electron to the nonmetal
(3) Allowing the metal cation and non-metal anion to come together.
a. What is the sign of the energy change for each of these three processes?
b. In general, what is the sign of the sum of the first two processes? Use examples to support your answer.
c. What must be the sign of the sum of the three processes?
d. Given your answer to part c, why do ionic bonds occur?
e. Given your explanations to part d, why is NaCl stable but not Na2Cl2 and NaCl2? What about MgO compared to MgO2 and Mg2O?