# Why do atoms have electron Affinity? [duplicate]

Atoms are stable so how can they pull electrons i.e how do they have any electron affinity at all?

• Which is more stable in the gas phase, F or F-? Another way to think about this is, why do we have anions and cations? – LordStryker Jun 25 '18 at 12:28

The electron affinity is the energy released when an electron is added to an atom $\ce{X(g) + e^- \to X^-(g)}$ and this energy released is, confusingly, by convention also a positive value. Thus for fluorine the electron affinity $\ce{F(g) + e^- \to F^-(g)} = 333$ kJ/mol) so this much energy is released, but is $-31$ for N atoms in which adding an electron is unfavourable (energy absorbing).