Q.51:- Define electron gain enthalpy. What are its units?
The energy which is released by an atom in gaining an electron from outside atom or ion to form negative ion (or anion) is called electron gain enthalpy (∆egH).
Unit of electron gain enthalpy is kJ/ mol.
In some cases, like in noble gas, atoms do not have any attraction to gain an electron. In that case energy has to be supplied.
Ne (g) + e– —> Ne– (g)
∆egH = + 116 kJ mol -1