CO2 Lewis Structure

CO2 Lewis Structure
CO2 lewis structure

CO2 (carbon dioxide) has one carbon atom and two oxygen atoms.

In the lewis structure of CO2, there are two double bonds around the carbon atom, with two oxygen atoms attached to it, and on each oxygen atom, there are two lone pairs.


Here’s how you can draw the CO2 lewis structure step by step.

Step #1: draw sketch
Step #2: mark lone pairs
Step #3: mark charges
Step #4: minimize charges
Step #5: minimize charges again (if there are)

Let’s break down each step in detail.

#1 Draw Sketch

  • First, determine the total number of valence electrons
Periodic table

In the periodic table, carbon lies in group 14, and oxygen lies in group 16.

Hence, carbon has four valence electrons and oxygen has six valence electrons.

Since CO2 has one carbon atom and two oxygen atoms, so…

Valence electrons of one carbon atom = 4 × 1 = 4
Valence electrons of two oxygen atoms = 6 × 2 = 12

And the total valence electrons = 4 + 12 = 16

Learn how to find: Carbon Valence Electrons and Oxygen Valence Electrons

  • Second, find the total electron pairs

We have a total of 16 valence electrons. And when we divide this value by two, we get the value of total electron pairs.

Total electron pairs = total valence electrons ÷ 2

So the total electron pairs = 16 ÷ 2 = 8

  • Third, determine the central atom

We have to place the least electronegative atom at the center.

Since carbon is less electronegative than oxygen, assume that the central atom is carbon.

Therefore, place carbon in the center and oxygens on either side.

  • And finally, draw the rough sketch
Rough sketch of CO2 lewis structure

#2 Mark Lone Pairs

Here, we have a total of 8 electron pairs. And two C — O bonds are already marked. So we have to only mark the remaining six electron pairs as lone pairs on the sketch.

Also remember that both (carbon and oxygen) are the period 2 elements, so they can not keep more than 8 electrons in their last shell.

Always start to mark the lone pairs from outside atoms. Here, the outside atoms are oxygens.

So for each oxygen, there are three lone pairs, and for carbon, there is zero lone pair because all six electron pairs are over.

Mark the lone pairs on the sketch as follows:

Lone pairs marked on CO2 lewis structure

#3 Mark Charges

Use the following formula to calculate the formal charges on atoms:

Formal charge = valence electrons – nonbonding electrons – ½ bonding electrons

For carbon atom, formal charge = 4 – 0 – ½ (4) = +2

For each oxygen atom, formal charge = 6 – 6 – ½ (2) = -1

Here, both carbon and oxygen atoms have charges, so mark them on the sketch as follows:

Formal charges marked on CO2 lewis structure

The above structure is not a stable lewis structure because both carbon and oxygen atoms have charges. Therefore, reduce the charges (as below) by converting lone pairs to bonds.

#4 Minimize Charges

Convert a lone pair of the oxygen atom to make a new C — O bond with the carbon atom as follows:

Lone pair of left oxygen is converted, but still there are charges

#5 Minimize Charges Again

Since there are charges on carbon and oxygen atoms, again convert a lone pair of the oxygen atom to make a new C — O bond with the carbon atom as follows:

Lone pair of right oxygen is converted, and got the stable lewis structure of CO2

In the above structure, you can see that the central atom (carbon) forms an octet. And the outside atoms (oxygens) also form an octet. Hence, the octet rule is satisfied.

Also, the above structure is more stable than the previous structures. Therefore, this structure is the stable lewis structure of CO2.

Next: SO2 Lewis Structure


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