Electron affinity

The electron affinity (Eea) of an atom or molecule is defined as the amount of energy released when an electron attaches to a neutral atom or molecule in the gaseous state to form an anion.

X(g) + e− → X−(g) + energy

This differs by sign from the energy change of electron capture ionization.[1] The electron affinity is positive when energy is released on electron capture.

In solid state physics, the electron affinity for a surface is defined somewhat differently (see below).

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