# What is the structure of I_3^(-)?

Aug 7, 2017

Do you want ${I}_{2}^{-}$ or ${I}_{3}^{-}$?

#### Explanation:

${I}_{3}^{-}$ is a 22 valence electron system which gives 3 lone pairs around the central iodine atom...according to $\text{VSEPR}$ the formal hybridization is $\mathrm{ds} {p}^{3}$, which gives a trigonal bipyramidal structure with respect to the electron pairs.

However because we describe structure on the basis of bonding pairs of electrons, not non-bonding pairs, the structure is linear to a first approx., because the non-bonding pairs of electrons occupy the equatorial plane.......

And if we write Lewis structures of the ion we get.....

$I - \stackrel{-}{I} - I$ in which the CENTRAL iodine has 8 VALENCE electrons, and thus it is assigned the formal negative charge.

With ${I}_{2}^{-}$ I don't know what you want..........