Ionic Dissociation of Gaseous Molecules

An isolated gaseous molecule XY dissociates into gaseous ions and Y as written in Eqn. 3—1  

Assuming that an isolated gaseous ion X is at the reference zero energy level as shown in Fig. 3-1, we define the occupied energy level of X ion (the unitary X ion donor level, molecule XY by the negative ionic dissociation 

The dissociation reaction given in Eqn. 3-1 is composed of the following steps  

The energy balance in the foregoing reaction cycle yields Eqn. 3-3  

The energy equation 3-3 may be used to define the ion energy level of ionic compound molecules. Fmthermore, this energy equation may also be used to define the ion energy level in covalently bonded compoimd molecules, though the physical meaning of the ion level in covalent compounds is a matter of discussion. 

---