What is the hybridization of the central iodine atom in the ion I_3^-?

• A. sp^2
• B. sp^3
• C. sp
• D. dsp^3

Answer: (C)

Verified step by step guidance

1. Identify the central atom and its bonding environment. In the ion I_3^-, the central atom is iodine (I), bonded to two other iodine atoms and carrying extra electrons due to the negative charge.
2. Determine the total number of valence electrons around the central iodine atom. Iodine has 7 valence electrons, and the ion has an extra electron due to the negative charge, so count all electrons from the central iodine and the bonding pairs.
3. Draw the Lewis structure of I_3^-. Place the two iodine atoms bonded to the central iodine atom, and distribute the remaining electrons as lone pairs to satisfy the octet rule for each atom.
4. Use the VSEPR theory to determine the electron pair geometry around the central iodine atom. Count both bonding pairs and lone pairs to find the steric number, which will help identify the hybridization.
5. Assign the hybridization based on the steric number: 2 regions of electron density correspond to sp, 3 to sp^2, 4 to sp^3, and 5 to dsp^3. For I_3^-, the steric number is 2, so the hybridization is sp.