What is the lewis structure for CH3CO2

What is the lewis structure for CH3CO2- ? What is the electron and molecular geometry? Draw the molecular geometry. Is it polar or non- polar?

The Correct Answer and Explanation is:

The Lewis structure for the acetate ion CH3CO2−\text{CH}_3\text{CO}_2^-CH3​CO2−​ (or CH3COO−\text{CH}_3\text{COO}^-CH3​COO−) is as follows:

Step 1: Count the valence electrons.

• Carbon (C) has 4 valence electrons.
• Hydrogen (H) has 1 valence electron (each hydrogen atom).
• Oxygen (O) has 6 valence electrons (each oxygen atom).
• The ion has a negative charge (−1-1−1), which adds 1 more electron.

Total valence electrons:4 (C)+3×1 (H)+2×6 (O)+1 (negative charge)=12 electrons.4 \ (\text{C}) + 3 \times 1 \ (\text{H}) + 2 \times 6 \ (\text{O}) + 1 \ (\text{negative charge}) = 12 \ \text{electrons}.4 (C)+3×1 (H)+2×6 (O)+1 (negative charge)=12 electrons.

Step 2: Draw the skeleton structure.

• Place the carbon in the center, with two oxygens attached to it.
• One oxygen is double-bonded to the carbon, and the other oxygen is single-bonded to the carbon and carries a negative charge.

Step 3: Distribute the electrons.

• The double-bonded oxygen gets 4 electrons (2 for the bond, 2 for lone pairs).
• The single-bonded oxygen gets 2 electrons for the bond and 3 lone pairs (6 electrons total), plus 1 additional electron due to the negative charge.

Step 4: Check for octets and minimize charges.

• The carbon has 4 bonds, so it satisfies the octet rule.
• The double-bonded oxygen has 2 bonds and 2 lone pairs, fulfilling the octet rule.
• The single-bonded oxygen has 1 bond, 3 lone pairs, and 1 negative charge, also fulfilling the octet rule.

Thus, the structure is:CH3C=O−\text{CH}_3\text{C} = \text{O}^- CH3​C=O−      ∣\ \ \ \ \ \ |       ∣    O\ \ \ \ \text{O}    O

Electron Geometry:

The electron geometry around the central carbon is trigonal planar because the carbon is connected to three regions of electron density (one double bond and two single bonds).

Molecular Geometry:

The molecular geometry is trigonal planar as well because there are no lone pairs on the carbon, and all regions of electron density are bonds.

Polarity:

• The molecule is polar. The C–O bond has a dipole moment due to the difference in electronegativity between carbon and oxygen. While the acetate ion has symmetry, the negative charge on the single-bonded oxygen causes a net dipole moment. Therefore, the ion is polar.

Now, I’ll generate the molecular geometry diagram for the acetate ion.