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Difficulty: HardCovalent and Dative (Coordinate) Bonding

In the carbon monoxide molecule (COCO), a triple covalent linkage holds the carbon and oxygen atoms together. Which statement correctly describes the nature of the bonding pairs between the two atoms and identifies the electron pair donor for the dative (coordinate) bond?

  1. There are three shared electron pairs in total, with oxygen donating the lone pair required for the coordinate bond.Answer
  2. B
    There are three shared electron pairs in total, with carbon donating the lone pair required for the coordinate bond.
  3. C
    There are two shared electron pairs in total, with oxygen donating the lone pair required for the coordinate bond.
  4. D
    There are four shared electron pairs in total, with both atoms contributing one lone pair each.

Answer

The carbon monoxide molecule features three shared pairs of electrons forming a triple bond, where oxygen serves as the donor atom contributing the lone pair for the coordinate covalent bond.
In carbon monoxide (COCO), carbon contributes 2 electrons and oxygen contributes 2 electrons to form two standard single covalent bonds. To allow carbon to attain a stable octet (8 valence electrons), oxygen donates both electrons from one of its lone pairs to form a third bond (dative/coordinate bond). Thus, there are 3 shared electron pairs (a triple bond), and oxygen is the donor.

Step-by-Step Solution

1
Determine valence electron counts for Carbon and Oxygen
Carbon (Group 14) has 4 valence electrons; Oxygen (Group 16) has 6 valence electrons.
Establishing valence electrons determines how many electrons are shared to complete octets.
2
Analyze standard covalent sharing between Carbon and Oxygen
Sharing 2 electrons from Carbon and 2 electrons from Oxygen forms 2 ordinary covalent bonds. This gives Oxygen 8 valence electrons, but leaves Carbon with only 6 valence electrons.
Two standard covalent bonds are insufficient to fulfill the octet rule for Carbon.
3
Identify the dative (coordinate) bond formation
Oxygen donates one of its remaining lone pairs into Carbon's vacant orbital to form a 3rd shared bond (coordinate bond), completing Carbon's octet.
This establishes a total of 3 shared pairs (a triple bond) with Oxygen acting as the donor atom.

Key Concept

Covalent and Dative (Coordinate) Bonding in Carbon Monoxide
Estimated Time:1m 30s
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Topics

Covalent and Dative (Coordinate) Bonding

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