For atoms, the first electron affinity value is almost always negative. This means that an electron addition can lead to a positive change in energy.
Because the second value is almost always positive, you must consider electron repulsion taking place. There will be an increase of the repulsion of the negative charge within the atom as more electrons are added to the system without any change in the number or protons. This causes the atom to attain a higher energy state, which results in a positive EA value when 2+ electrons are added.
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