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Difficulty: MediumCovalent and Dative (Coordinate) Bonding

Match each chemical species in Column A with its correct bonding description in Column B.

  • Hydronium ion (H3O+H_3O^+)Contains a coordinate bond formed by an oxygen atom donating a lone pair to a hydrogen ion (H+H^+)
  • Ammonium ion (NH4+NH_4^+)Contains a coordinate bond formed by a nitrogen atom donating a lone pair to an incoming H+H^+ ion
  • Aluminum chloride dimer (Al2Cl6Al_2Cl_6)Contains bridging chlorine atoms that donate lone pairs into vacant orbitals of electron-deficient aluminum atoms
  • Carbon monoxide (COCO)Contains a triple bond consisting of two covalent bonds and one coordinate bond directed from oxygen to carbon

Answer

The correct pairings are: Hydronium ion (H3O+H_3O^+) matches with oxygen donating a lone pair to a proton; Ammonium ion (NH4+NH_4^+) matches with nitrogen donating a lone pair to a proton; Aluminum chloride dimer (Al2Cl6Al_2Cl_6) matches with bridging chlorine atoms donating lone pairs to electron-deficient aluminum centers; Carbon monoxide (COCO) matches with a triple bond containing two covalent bonds and one coordinate bond from oxygen to carbon.
Each chemical species correctly corresponds to its specific electron pair donor-acceptor behavior: H3O+H_3O^+ relies on oxygen lone pair donation to H+H^+, NH4+NH_4^+ relies on nitrogen lone pair donation to H+H^+, Al2Cl6Al_2Cl_6 uses bridging chlorine lone pairs to complete aluminum octets, and COCO uses a dative bond from oxygen to carbon alongside two covalent bonds.

Step-by-Step Solution

1
Analyze the coordinate bonding in simple protonated ions (H3O+H_3O^+ and NH4+NH_4^+).
In H3O+H_3O^+, oxygen in H2OH_2O acts as the electron pair donor to H+H^+. In NH4+NH_4^+, nitrogen in NH3NH_3 acts as the electron pair donor to H+H^+.
Distinguishing between oxygen and nitrogen donor atoms correctly pairs the protonated species.
2
Examine the structure of the aluminum chloride dimer (Al2Cl6Al_2Cl_6).
Monomeric AlCl3AlCl_3 is electron-deficient (6 valence electrons around aluminum). Dimerization occurs when a lone pair from a chlorine atom on one AlCl3AlCl_3 molecule is donated to the aluminum atom of another AlCl3AlCl_3 molecule, creating two coordinate bridges.
This bridge satisfies the octet rule for both aluminum atoms in Al2Cl6Al_2Cl_6.
3
Determine the bonding in carbon monoxide (COCO).
Carbon has 4 valence electrons and oxygen has 6. To complete octets for both atoms, oxygen shares two pairs covalently and donates one lone pair to form a coordinate bond, creating a triple bond (C≡OC \equiv O).
This establishes that oxygen is the donor and carbon is the acceptor in the dative component of the triple bond.

Key Concept

Coordinate (Dative) Covalent Bonding and Electron Pair Donation
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Topics

Covalent and Dative (Coordinate) Bonding

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