Multiple Choice
Which of the following interhalogen compounds has a Lewis structure that violates the octet rule by having more than eight electrons around the central atom?
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11. Bonding & Molecular Structure
Lewis Dot Structures: Exceptions
Multiple Choice
Which of the following is a common error found in invalid Lewis dot structures that are exceptions to the octet rule?
A
Using double bonds for noble gases
B
Placing fewer than eight electrons around a third-period element
C
Assigning a formal charge of zero to all atoms
D
Assigning more than eight electrons to a second-period element
Verified step by step guidance1
Understand the octet rule: it states that atoms tend to form bonds until they are surrounded by eight electrons in their valence shell, which is especially true for second-period elements (like C, N, O, F).
Recognize that second-period elements cannot have expanded octets because they lack available d orbitals, so placing more than eight electrons around them is an error in Lewis structures.
Note that third-period elements and beyond can have expanded octets due to available d orbitals, so placing fewer than eight electrons around them is not necessarily an error.
Realize that noble gases typically do not form bonds, so using double bonds for noble gases is uncommon and generally incorrect in Lewis structures.
Understand that assigning a formal charge of zero to all atoms is not always possible or correct; formal charges help identify the most stable Lewis structure, so ignoring them can lead to invalid structures.
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