In the carbon skeleton structure below, identify the carbon atom(s) with sp2 hybridization. 4th attempt Jd See Periodic Table See Hint TIP: Select each sp2 hybridized carbon: Selected atoms will be highlighted in green:
The Correct Answer and Explanation is:
To determine which carbon atoms in a carbon skeleton are sp² hybridized, it’s necessary to examine their bonding environment. sp² hybridization occurs when a carbon atom forms three sigma (σ) bonds and one pi (π) bond, typically seen in double bonds or in aromatic rings like benzene.
Correct Answer
The sp² hybridized carbon atoms in a structure include:
- Each carbon involved in a C=C double bond.
- Each carbon in a benzene ring or any conjugated planar ring structure.
These carbon atoms form three sigma bonds (including bonds to other carbon or hydrogen atoms) and have an unhybridized p orbital that overlaps to form a pi bond.
Explanation
Hybridization is a concept in valence bond theory that explains the shapes of molecules based on the mixing of atomic orbitals. For carbon, three major hybridization states are possible: sp³, sp², and sp.
The sp² hybridization involves one s orbital and two p orbitals combining to form three sp² hybrid orbitals. This configuration leads to a trigonal planar geometry with 120° bond angles. The remaining unhybridized p orbital participates in the formation of a pi bond, which is the defining feature of a double bond.
In carbon skeleton structures, sp² carbon atoms are easily recognized by their involvement in double bonds or aromatic rings. In double bonds, one bond is a sigma bond (from the overlap of sp² orbitals), and the other is a pi bond (from the side-to-side overlap of p orbitals). In aromatic systems, such as benzene, each carbon is bonded to two adjacent carbon atoms and one hydrogen, with a delocalized pi system spread across the ring.
By visually analyzing the carbon structure, carbon atoms participating in double bonds or aromatic rings should be identified. These atoms have precisely three regions of electron density—consistent with sp² hybridization.
Therefore, all carbon atoms in double bonds or aromatic rings must be selected, as they conform to the bonding pattern and geometry characteristic of sp² hybridization.
