To determine the bond order of the acetate ion (CH₃COO⁻), we need to analyze its structure.
The acetate ion has the following Lewis structure:
- It consists of a methyl group (CH₃) and a carboxylate group (COO⁻).
- The carboxylate group has one carbon atom bonded to two oxygen atoms. One of these oxygen atoms has a double bond with the carbon, while the other has a single bond and carries a negative charge.
The Lewis structure can be represented as:
O
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CH3-C-O⁻
In the carboxylate portion (COO⁻), the carbon atom is bonded to two oxygen atoms:
- One oxygen atom has a double bond to the carbon (C=O).
- The other oxygen atom has a single bond to the carbon (C-O) and carries a negative charge.
To calculate the bond order:
- The bond order of a bond is defined as the number of bonding pairs of electrons divided by the number of bonds between the atoms.
- For the carbon-oxygen double bond (C=O), the bond order is 2.
- For the carbon-oxygen single bond (C-O), the bond order is 1.
In the acetate ion, the carbon atom is effectively acting as bonded within a resonance structure system, where the single and double bonds can interchange. Therefore, the average bond order can be estimated as follows:
- The carbon-oxygen single bond contributes a bond order of 1.
- The carbon-oxygen double bond contributes a bond order of 2.
To calculate the average bond order between carbon and the two oxygen atoms in COO⁻:
Total bond order = \( \frac{(1 + 2)}{2} = \frac{3}{2} = 1.5 \).
Thus, the bond order for the C-O bonds in CH₃COO⁻ is 1.5.