Which of the following statements correctly describes the Lewis dot structure of the AsBr_5 molecule?

• A. Arsenic (As) is the central atom, surrounded by five bromine (Br) atoms, each bonded by a single bond, and As has two lone pairs.
• B. Arsenic (As) is the central atom, surrounded by five bromine (Br) atoms, each bonded by a double bond, and As has one lone pair.
• C. Arsenic (As) is the central atom, surrounded by five bromine (Br) atoms, each bonded by a single bond, and As has no lone pairs.
• D. Bromine (Br) is the central atom, surrounded by five arsenic (As) atoms, each bonded by a single bond, and Br has two lone pairs.

Answer: (C)

Verified step by step guidance

1. Identify the central atom in the molecule AsBr_5. Typically, the less electronegative atom or the atom that can form more bonds is the central atom. Here, arsenic (As) is less electronegative than bromine (Br), so As is the central atom.
2. Determine the total number of valence electrons available. Arsenic (As) has 5 valence electrons, and each bromine (Br) has 7 valence electrons. Since there are 5 bromine atoms, total valence electrons = 5 (from As) + 5 × 7 (from Br) = 5 + 35 = 40 electrons.
3. Draw single bonds between the central arsenic atom and each of the five bromine atoms. Each single bond uses 2 electrons, so 5 bonds use 10 electrons, leaving 30 electrons to be distributed as lone pairs.
4. Distribute the remaining electrons as lone pairs to satisfy the octet rule for the bromine atoms first. Each bromine needs 6 more electrons (3 lone pairs) to complete its octet, so 5 bromines × 6 electrons = 30 electrons, which matches the leftover electrons.
5. Check the central arsenic atom's electron count. It has 5 single bonds (10 electrons) and no lone pairs, which means arsenic has an expanded octet (10 electrons), which is allowed for elements in period 4 or higher. Therefore, arsenic has no lone pairs in AsBr_5.