Question

what is the hybridization of the central atom in the triiodide (i₃⁻) anion?

Explanation:

Step1: Determine the Lewis structure

The $I_3^-$ ion has a central iodine atom bonded to two other iodine atoms and has 3 lone - pairs on the central iodine. The total number of electron - groups (bonding + non - bonding) around the central iodine is 5 (2 bonds and 3 lone pairs).

Step2: Use the VSEPR theory for hybridization

According to VSEPR theory, when the number of electron - groups around a central atom is 5, the hybridization is $sp^3d$.

Answer:

$sp^3d$