# Iodine is an element in Group 7A of the periodic table. Which type of ion does iodine form?

Dec 30, 2016

Iodine has a high nuclear charge..........that is not terribly well shielded by its incomplete valence shell of electrons.

#### Explanation:

..........Iodine thus tends to attract electron density, and the addition of a single electron will provide a full valence shell. Thus it is reduced and forms an $\text{iodide ion}$, ${I}^{-}$. All the halogens form this ion upon reduction:

$\frac{1}{2} {X}_{2} + {e}^{-} \rightarrow {X}^{-}$