Electron affinities for the simplest ten elements are shown across the top of this page.

Note:
Electron affinities are harder to measure than ionization energies, and these values are only approximate.

Neon has no electron affinity, because it already has its full complement of eight outer electrons. Fluorine has the largest electron affinity, 83.5 kilocalories per mole; thus the F ion is formed easily. Oxygen has a smaller electron affinity because the net charge pulling on the outer electrons is +6 rather than +7. The affinities of other neutral atoms of the second-shell elements for extra electrons are weaker still.