Draw a Lewis structure for NOBr
The correct answer and explanation is:
Correct Lewis Structure for NOBr (Nitrosyl Bromide):
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:Br:
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O=N–Br
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Explanation (300 words):
To draw the correct Lewis structure for NOBr (nitrosyl bromide), begin by calculating the total number of valence electrons. Nitrogen (N) has 5 valence electrons, oxygen (O) has 6, and bromine (Br) has 7. The total is 5 + 6 + 7 = 18 valence electrons.
Next, determine the central atom. Nitrogen is the least electronegative of the three and will serve as the central atom. Place oxygen and bromine on either side of nitrogen. Arrange the atoms as O–N–Br.
Distribute electrons starting with single bonds between N and O, and N and Br. That accounts for 4 electrons (2 per bond), leaving 14.
Complete the octets of the outer atoms first. Oxygen needs 6 more electrons to complete its octet, and bromine also needs 6 more. That uses 12 more electrons, leaving 2.
The remaining 2 electrons are placed as a lone pair on nitrogen. However, this structure gives nitrogen only 6 electrons (1 bond with O, 1 bond with Br, and 1 lone pair), so a double bond is formed between nitrogen and oxygen to satisfy the octet rule. This gives nitrogen 8 electrons: 1 single bond with Br (2), 1 double bond with O (4), and 1 lone pair (2).
Oxygen gets two lone pairs (4 electrons) and shares 4 electrons in the double bond, completing its octet. Bromine has three lone pairs (6 electrons) and one single bond with nitrogen, which also completes its octet.
The final structure has nitrogen in the center with a double bond to oxygen and a single bond to bromine. Formal charges are minimized in this configuration: oxygen gets a formal charge of 0, nitrogen gets a formal charge of 0, and bromine gets a formal charge of 0, indicating a stable structure.
This Lewis structure shows bonding and nonbonding electrons clearly and respects the octet rule.