A Levels Chemistry (9701)•9701/12/O/N/19
Explanation
Lewis Structure of CO Molecule Steps:
- Calculate total valence electrons: carbon (4) + oxygen (6) = 10 electrons.
- Form a triple bond between C and O, accounting for 6 shared electrons.
- Distribute remaining 4 electrons as one lone pair on C and one lone pair on O.
- Confirm structure: :C≡O: with two lone pairs total.
Why A is correct:
- The Lewis structure of CO shows exactly two lone pairs (one on each atom), satisfying the octet rule with 10 valence electrons.
Why the others are wrong:
- B: No coordinate bond from O to C in the primary Lewis structure; triple bond is covalent, though resonance forms exist.
- C: Triple bond has one σ bond and two π bonds, not two σ bonds from O to C.
- D: Option incomplete, provides no valid feature.
Final answer: A
Topic: Chemical bonding
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