What is state of hybridisation of C in CO3^2 –
The Correct Answer and Explanation is:
The carbon atom in the carbonate ion (CO₃²⁻) is sp² hybridized.
Explanation:
The carbonate ion (CO₃²⁻) has a trigonal planar structure, meaning that all three oxygen atoms are symmetrically arranged around the central carbon atom. The carbon atom forms three sigma bonds with the three oxygen atoms, and since there is no lone pair of electrons on carbon, the electron cloud around the carbon is evenly distributed.
- Electron Domains: The carbon atom has three electron domains around it—one for each of the sigma bonds with oxygen atoms. In the idealized bonding model, the three domains are spread evenly around the carbon in a plane, forming a 120° angle between them.
- Bonding: The carbon-oxygen bonds in CO₃²⁻ are not purely single bonds, but rather have partial double bond character due to resonance. This means that the bond order between carbon and each oxygen is effectively 1⅓, which is an average of three equivalent bonds. This delocalization of electrons is possible because of the resonance structures, where the double bond is not fixed to one oxygen but rotates among all three oxygens.
- Hybridization: To accommodate the three bonding regions and the trigonal planar geometry, the carbon atom undergoes sp² hybridization. In this hybridization, one s orbital and two p orbitals mix to form three sp² hybrid orbitals. These hybrid orbitals form the sigma bonds with the oxygen atoms, while the remaining p orbital on carbon overlaps with the p orbitals on oxygen to form the delocalized pi bonds responsible for the resonance.
Conclusion:
Thus, the carbon atom in CO₃²⁻ is sp² hybridized because it forms three equivalent sigma bonds and participates in delocalized pi bonding, leading to a trigonal planar structure with 120° bond angles.
