Taking into account the definition of electron affinity, negative electron affinity means that the anion of the element is more stable than the neutral atom.
Electron affinity is the energy exchanged when a neutral, gaseous atom, and in its ground state, captures an electron to form the anion.
In other words, electronon Affinity is the energy that is given off when a neutral atom in the gaseous state captures an electron to become a negative ion.
The value can be positive or negative. A negative electron affinity means energy must enter in order to bind an electron to the ion, being an endothermic process. If electron affinity is positive, the process is exothermic and occurs spontaneously.
Then, the negative electron affinity (energy is released) occurs when the atoms acquire a more stable configuration when capturing an electron, so the attractive force will predominate. Positive electron affinity (energy is absorbed): occurs when you have to provide energy to the atom to capture the ion.
In summary, negative electron affinity means that the anion of the element is more stable than the neutral atom.
Learn more:
