# What is the electron affinity of oxygen?

Nov 8, 2015

Electron affinity is defined as the enthalpy change when 1 mol of atoms, accepts 1 mol of electrons to form 1 mol of anions. Both reactants and products are specified to be in the gas phase.

#### Explanation:

So, electron affinity measures enthalpy change for the following reaction:

$E \left(g\right) + {e}^{-} \rightarrow {E}^{-} \left(g\right)$. Where $E$ is the generic element.

I have no idea what it is for $O$. Because oxygen is towards the right of the Periodic Table I suspect it will be negative. Why can I make this assessment?