Chemistry - Thermochemistry Question with Solution | TestHub

When one mole of electrons is added to one mole of isolated gaseous atoms (X) to convert it into a negative ion, the enthalpy change accompanying the process is defined as the Electron Gain Enthalpy ($\Delta H_{EG}$). Electron gain enthalpy provides a measure of the ease with which an atom adds an electron to form an anion, as represented by:

$$X\left(g\right)+e^{-}\to X^{-}\left(g\right)$$