Ionization energy is defined as the minimum energy required to remove a single valence electron from an isolated gaseous atom.
Electron affinity is defined as the amount of energy released or absorbed when a single electron is added to the valence shell of an isolated gaseous atom.
The following reaction can be written as the sum of two reactions, one of which relates to ionization energy and one of which relates to electron affinity:
a. What is the reaction that corresponds to the first ionization energy of sodium, Na?
b. What is the reaction that corresponds to the electron affinity of chlorine, Cl?