Draw Lewis structure(s) for the carbon dioxide molecule (CO2)

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Draw Lewis structure(s) for the carbon dioxide molecule (CO2).

If there are equivalent resonance structures, draw all of them. Draw one structure per sketcher box, and separate added sketcher boxes with the ? symbol. Do not include overall ion charges or formal charges in your drawing. Do not draw double bonds to oxygen unless they are needed in order for the central atom to obey the octet rule.

What is the bond order of the C–O bonds in the carbonate ion ?(enter a decimal number)

The Correct Answer and Explanation is :

Lewis Structures for Carbon Dioxide (CO₂)

The Lewis structure of CO₂ consists of a carbon atom (C) in the center, bonded to two oxygen atoms (O) with double bonds. Each oxygen atom also has two lone pairs of electrons. Here’s the structure:

O = C = O

There are no resonance structures for CO₂ because its structure with double bonds satisfies the octet rule for all atoms and minimizes formal charges.

Bond Order in Carbonate Ion (CO₃²⁻)

The carbonate ion (CO₃²⁻) has three resonance structures where the double bond shifts among the three oxygen atoms. The Lewis structures for the carbonate ion are:

  1. Double bond between C and one O, single bonds with the other two O atoms. Each single-bonded oxygen has three lone pairs.
  2. The double bond shifts to the second O.
  3. The double bond shifts to the third O.

The resonance structures look like this:

 O      O      O
 ||     |      |
 C  -   C  -   C
/ \    / \    / \
O  O   O  O   O  O

Bond Order Explanation

The bond order is the average of the bond types across all equivalent resonance structures. In carbonate:

  1. There are three C-O bonds, shared among one double bond and two single bonds in each structure.
  2. The double bond rotates between the oxygen atoms in resonance.
  3. The bond order is calculated as: Bond Order=Total Bonding PairsNumber of Bonds\text{Bond Order} = \frac{\text{Total Bonding Pairs}}{\text{Number of Bonds}} There are 4 bonding pairs (1 double bond + 2 single bonds in each resonance structure) shared over 3 bonds.

Bond Order=43=1.33\text{Bond Order} = \frac{4}{3} = 1.33

Final Answer

The bond order of the C-O bonds in the carbonate ion is 1.33.

This fractional bond order arises because of the delocalized electrons shared across the resonance structures, giving the bonds partial double-bond character. This delocalization contributes to the stability of the carbonate ion.

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