What is the formal charge on the central iodine atom in a molecule of ICl_3?

• A. -1
• B. +2
• C. 0
• D. +1

Answer: (C)

Verified step by step guidance

1. Identify the number of valence electrons for the central iodine atom. Iodine is in group 17, so it has 7 valence electrons.
2. Determine the number of bonds iodine forms with chlorine atoms. In ICl_3, iodine forms 3 single bonds with chlorine atoms.
3. Count the number of lone pair electrons on iodine. Since iodine can expand its octet, consider the total electrons around iodine and subtract bonding electrons to find lone pairs.
4. Use the formal charge formula: \(\text{Formal Charge} = \text{Valence electrons} - \text{Nonbonding electrons} - \frac{1}{2} \times \text{Bonding electrons}\).
5. Plug in the values for iodine: valence electrons (7), nonbonding electrons (from lone pairs), and bonding electrons (from 3 bonds), then calculate the formal charge to verify it is zero.