The sigma bond between the carbon and oxygen in CO2 is formed from which two orbitals
The correct answer and explanation is:
Correct Answer:
The sigma (σ) bond between the carbon and oxygen atoms in carbon dioxide (CO₂) is formed from the sp hybrid orbital of carbon and the sp² hybrid orbital of oxygen.
Explanation (Approx. 300 words):
Carbon dioxide (CO₂) is a linear molecule with the structure O=C=O. It consists of one carbon atom double bonded to each of two oxygen atoms. Each of these double bonds is composed of one sigma (σ) bond and one pi (π) bond.
Hybridization of Carbon in CO₂:
Carbon has the ground-state electron configuration of 1s² 2s² 2p². To form bonds, carbon undergoes sp hybridization in CO₂. In this hybridization, one 2s orbital and one 2p orbital mix to form two sp hybrid orbitals that align linearly at 180° angles. These sp orbitals form the sigma bonds with oxygen atoms, and the unhybridized p orbitals are used for the pi bonds.
Hybridization of Oxygen in CO₂:
Oxygen, with a ground-state configuration of 1s² 2s² 2p⁴, typically undergoes sp² hybridization in CO₂. Each oxygen atom uses one of its sp² hybrid orbitals to form a sigma bond with carbon. The remaining sp² orbitals hold lone pairs, while the unhybridized p orbital participates in the pi bond.
Sigma Bond Formation:
The sigma bond is the first bond formed between two atoms and involves end-to-end (axial) overlap of orbitals. In CO₂:
- The carbon atom uses an sp hybrid orbital.
- The oxygen atom uses an sp² hybrid orbital.
These orbitals overlap head-on to form a strong sigma bond along the internuclear axis.
Pi Bond Formation:
The remaining unhybridized p orbitals on carbon and oxygen overlap sideways to form pi bonds, completing the double bonds.
In conclusion, the sigma bond in each C=O bond in CO₂ arises from the overlap of a carbon sp hybrid orbital with an oxygen sp² hybrid orbital.