Ionization Enthelpy, Electron Gain Enthelpy and Electron Affinity

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Ionization Enthalpy is the energy needed to remove an electron from an atom, while Electron Gain Enthalpy is the energy required to add an electron. Electron Affinity is often described as the negative of Electron Gain Enthalpy, indicating that when an electron is added, energy can be released, resulting in a negative value. The discussion raises a question about why Electron Gain Enthalpy can have both negative and positive values, whereas Ionization Enthalpy consistently requires energy input. Understanding these concepts clarifies the thermodynamic principles governing electron interactions in atoms.
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Ionization Enthalpy is defined as the amount of energy required to remove an atom's electron (can be valence or consecutive) ... this definition doesn't sound so complex. The definition of Electron Gain Enthalpy - it is the amount of energy required to add an electron. But, what is Electron Affinity ? One book says it is the negative of electron gain enthalpy. Then, there is some thermodynamic rule saying negative value of electron gain enthalpy indicates that energy has to be supplied and positive value indicates energy is released. My question is how can electron gain enthalpy have both negative and positive values but ionisation enthalpy doesn't have. Also please explain what the differnece between affinity and gain enthalpy is.
Thanks in advance ...
 
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i.e. in the case of electron gain enthalpy energy is released and in ionization enthalpy energy is gained.
 

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