# What is the sign of the enthalpy term in an ionization reaction?

Jul 2, 2017

Given the current conventions, they should be POSITIVE........

#### Explanation:

Consider the ionization reaction......

$\text{Atom(g)}$$\rightarrow$${\text{Atom(g)}}^{+} + {e}^{-}$

We separate an electron from a positively nucleus. Reasonably, energy should be required to do this. And so we could rewrite the reaction to reflect this, i.e.......

${\text{Atom(g)"+Deltararr"Atom(g)}}^{+} + {e}^{-}$

So given that this is an endothermic reaction, $\Delta$ should be POSITIVE........