# Define Ionization energy. ?

Apr 23, 2018

Energy required to ionize 1 mol of gaseous atoms.

#### Explanation:

Ionization energy is the energy required to remove the outermost electrons from 1 mol atoms in gaseous state.

Alkali metals have the least Ionization energy and Noble gases have the highest.

$E \left(g\right)$ $\rightarrow$ ${E}^{+} \left(g\right)$ $+$ ${e}^{-}$ : $\Delta H =$Ionization energy

Here $E$ is any element.