According to this ChemistryLibretexts website and this StackExchange answer, 1st electron affinites are negative and 2nd electron affinities are positive.
However, according to this Study.com website, 1st electron affinity (energy released) is positive.
Both contradicting websites address the point that when electrons are added to a neutral atom, energy is released. But the only problem is that one website says that when this exothermic reaction occurs, the 1st electron affinity is negative, while the other states that the 1st electron affinity is positive. Which one is right?
Answer
Well, the first electron that is taken up any atom other than a noble gas atoms or light atoms with half filled or full filled orbitals, is taken up with a release of energy, so ∆E should be negative. For the other atoms, they are already in the preferred electronic configuration, so they reluctantly take up electrons, tHus having a positive ∆E. In case of the second electron acceptance, there is repulsion of the electron by the negative charge gained by the atom, so it depends upon the situation. If the second electron acceptance leads to a stabler electronic configuration, like a noble gas, then the second ∆E may also be negative.
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