Which of the following statements correctly describes the Lewis dot structure of the BrF_2^- ion?

• A. Bromine is the central atom, surrounded by two fluorine atoms and one lone pair, with a total of 8 electrons around bromine.
• B. Bromine is the central atom, surrounded by two fluorine atoms and three lone pairs, with a total of 10 electrons around bromine.
• C. Bromine is the central atom, surrounded by two fluorine atoms and no lone pairs, with a total of 6 electrons around bromine.
• D. Bromine is the central atom, surrounded by three fluorine atoms and two lone pairs, with a total of 10 electrons around bromine.

Answer: (B)

Verified step by step guidance

1. Step 1: Determine the total number of valence electrons for the BrF_2^- ion. Bromine (Br) has 7 valence electrons, each fluorine (F) has 7 valence electrons, and the negative charge adds 1 extra electron. So, total electrons = 7 (Br) + 2 × 7 (F) + 1 (charge).
2. Step 2: Identify the central atom, which is typically the least electronegative atom. In this case, bromine is the central atom, with two fluorine atoms bonded to it.
3. Step 3: Draw single bonds between bromine and each fluorine atom. Each bond accounts for 2 electrons, so subtract these bonding electrons from the total valence electrons.
4. Step 4: Distribute the remaining electrons as lone pairs to satisfy the octet rule for the fluorine atoms first, since fluorine atoms typically have three lone pairs each to complete their octets.
5. Step 5: Assign any leftover electrons to the central bromine atom as lone pairs. Count the total electrons around bromine (bonding + lone pairs) to verify the correct number of electrons (10 electrons) around bromine, consistent with an expanded octet.