What is the geometric structure of acetone (CH3)2CO. Indicate the bond angles and specify if they are non-ideal.
The Correct Answer and Explanation is :
The geometric structure of acetone (CH₃)₂CO, also known as dimethyl ketone, consists of a central carbonyl group (C=O) attached to two methyl groups (CH₃). Acetone has a trigonal planar geometry around the central carbonyl carbon (C=O), with bond angles of approximately 120°.
Bond Angles and Geometry:
- Central Carbonyl Carbon (C=O): The carbonyl carbon is sp² hybridized, meaning it has three regions of electron density (one double bond with oxygen and two single bonds with two methyl groups). The geometry around this carbon is trigonal planar, with bond angles close to 120°. This ideal bond angle results from the sp² hybridization of the carbon atom.
- Methyl Groups (CH₃): Each methyl group (CH₃) is attached to the central carbon by a single bond, and the carbon in the methyl group is sp³ hybridized. The bond angles within each CH₃ group are approximately 109.5°, which is the ideal bond angle for sp³ hybridized carbon atoms.
Non-Ideal Bond Angles:
While the bond angles in the central C=O group are close to 120° due to the sp² hybridization of the carbon, there are slight deviations in acetone’s overall molecular geometry. These deviations occur because of the differences in hybridization between the central carbon (sp²) and the carbon in the methyl group (sp³). In reality, the bond angles around the central carbon may be slightly compressed or distorted due to the presence of the bulky methyl groups. The C-H bond angles within each methyl group could also be slightly altered due to the influence of the oxygen atom in the carbonyl group.
In summary, the geometry of acetone is primarily trigonal planar around the carbonyl carbon, with the ideal bond angle of 120°, but slight distortions can occur due to the non-ideal nature of the bonds between sp² and sp³ hybridized atoms.