Carbon monoxide (CO) Molecule Lewis Structure

Carbon monoxide (CO) is a diatomic molecule and contains carbon and oxygen atoms. Lewis structure of CO molecule contains a triple bond. Both Carbon and Oxygen atoms have one lone pair in their valence shells.


CO lewis structure

CO carbon monoxide lewis structure

In the lewis structure of carbon monoxide, both atoms have eight electrons in their valence shells. However, oxygen atoms has a +1 charge and carbon atom has a +1 charge. In next sections, we will draw CO lewis structure step by step.



Carbon monoxide

Carbon monoxide is a very toxic gaseous molecule at room temperature and formed due to incomplete combustion of products (Due to lack of oxygen gas). You should never try to expose to this carbon monoxide gas. However, carbon monoxide is easily oxidized to carbon dioxide gas in the presence of oxygen gas


Now, we will learn how to draw the carbon monoxide lewis structure step by step.

Steps of drawing lewis structure of CO molecule

There are guidelines (several steps) to draw a lewis structure. Number of steps can be changed according the complexity of the molecule or ion. Whether CO molecule seems as a simple molecule, there are important things to consider drawing the lewis structure. However those all steps are mentioned and explained in detail in this tutorial for your knowledge.

  1. Find total number of electrons of the valance shells of carbon and oxygen atoms
  2. Total electrons pairs existing as lone pairs and bonds
  3. Center atom selection
  4. Mark lone pairs on atoms
  5. Mark charges on atoms if there are charges.
  6. Check the stability and minimize charges on atoms by converting lone pairs to bonds to obtain best lewis structure.


Total number of electrons of the valance shells of CO molecule

Carbon is a group IVA element in the periodic table and contains four electrons in its last shell. Carbon is a group VIA element in the periodic table and contains six electrons in its last shell. Now, we know how many electrons are there in valence shells of carbon and oxygen atoms.


  • valence electrons given by carbon atoms = 4 * 1 = 4
  • valence electrons given by oxygen atoms = 6 * 1 = 6

  • Total valence electrons = 10


Total valence electrons pairs

Total valance electrons pairs = σ bonds + π bonds + lone pairs at valence shells

Total electron pairs are determined by dividing the number total valence electrons by two. For, CO molecule, Total pairs of electrons are five in their valence shells.



Center atom selection of CO molecule

Center atom selection in lewis structure drawing can be a long process if a molecule is complex. Because, there are only two atoms in carbon monoxide molecule, we do not need to worry much about center atom selection. Therefore, just draw a single bond between carbon atom and oxygen atom.

CO basic sketch

Lone pairs on atoms

After determining the center atom and sketch of CO molecule, we can start to mark lone pairs on atoms. Remember that, there should be total of five electron pairs as lone pairs and bonds.

  • There is already one bond in the drawn sketch. So, there are four remaining lone pairs to mark on carbon and oxygen atoms.
  • Because, there is no center atom, we can start to mark remaining lone pairs on oxygen atom. Oxygen atom will take three lone pairs.
  • Now, one valence electron pair is remaining and it is marked on carbon atom.
mark lone pairs on carbon and oxygen atoms in CO


Mark charges on atoms

There are charges on carbon and oxygen atoms to mark in the above structure. Marking of charges on atoms is a compulsary step to decide the stability of a molecule.

mark charges on carbon and oxygen atoms in CO

Check the stability and minimize charges on atoms by converting lone pairs to bonds

Because, there are charges on carbon and oxygen atoms. Also octal is not completed in carbon atom. Therefore, above structure is not stable and need to convert a lone pair on oxygen atoms to a bond as below.

reduces charges and complete octal of carbon atoms in CO

However above structure is still unstable because octal is not still completed in carbon atom. So, we need to convert one more lone pair on oxygen atom to a bond. Then, there will be a triple bond between carbon and oxygen atoms. But, there will be +1 charge on oxygen atom and -1 charge on carbon atom.

complete octal in carbon atom in carbon monoxide molecule


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Lewis Structures of Molecules



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