I was wondering what the difference between a positive electron affinity and negative electron affinity is. From what I've read, it seems like they both release energy. Also, can you guys give some examples?
"All elements have a positive electron affinity, but older texts mistakenly report that some elements such as inert gases have negative Eea, meaning they would repel electrons. This is not recognized by modern chemists."
"Eea is not limited to the elements but also applies to molecules. For instance the electron affinity for benzene is negative, as is that of naphthalene, while those of anthracene,phenanthrene and pyrene are positive."
Those are quotes from Wikipedia
I don't know how those electron affinities are derived though.