Structure, Geometry, and Hybridization of CO Lewis

Carbon monoxide (CO) is a combustible, tasteless, and odourless gas that is very toxic to animals in nature. When carbon monoxide concentrations above 35 parts per million, it uses haemoglobin, an oxygen carrier, to go throughout the body. Carbon monoxide is formed when carbon dioxide (CO2) or another carbon-containing substance is partially oxidised.

The Lewis structure, commonly known as the electron dot structure, is a simple way of expressing the number of valence electrons in an atom or molecule.

In addition, the structure aids in identifying the number of lone pairs of electrons present in an atom and how they interact with one another during bond formation.

The structure is represented by dots that represent the number of valence electrons in an atom and lines that represent the number of bonds that will form.

Eight valence electrons are the maximum number that can be written surrounding an atom. The Lewis structure of a single carbon and oxygen atom is depicted here.

Carbon has an atomic number of six, giving it the electrical structure 1s2 2s2 2p2.

Because the 2p shell can only hold up to six electrons, there is a four-electron shortage.

As a result, carbon has four valence electrons that are ready to make a bond in order to keep its atomic structure stable.

An oxygen atom, on the other hand, has an atomic number of eight, giving it the electrical configuration 1s2 2s2 2p4.

There is a two-electron shortage in the 2p shell, which can hold up to six electrons in total.

As a result, oxygen possesses a total of six valence electrons, all of which are available to form a bond in order to stabilise its electrical structure.

It’s important to remember that the more valence electrons an atom has, the more difficult it is for it to transfer them. Because the creation of a strong link requires a lot of energy.

What are the electrons of Valence?

The electrons in an atom’s outermost shell, also known as the valence electrons, participate in the formation of bonds with other atoms in order to achieve stability.

Because non-noble elements’ outermost orbits are not completely filled and thus unstable, the valence electrons rapidly react with a neighbouring atom to stabilise the orbit.

What does the Octet rule entail?

According to the octet rule, an atom’s outermost shell can have a maximum of eight valence electrons. The carbon atom has four valence electrons and a four-electron deficit.

An oxygen atom, on the other hand, has six valence electrons and a two-electron shortfall.

The Lewis structure is written in such a way that it fills both the atom and the molecule deficiency in the case of carbon monoxide (CO).

Carbon Monoxide’s Lewis Structure (CO)

It may be deduced from the aforementioned Lewis structures of single oxygen and carbon atoms that carbon and oxygen atoms each have 10 valence electrons that will participate in bond formation.

The steps to drawing the Lewis structure of carbon monoxide are as follows:

To find total valence electrons, use the following formula: It takes ten to make carbon monoxide.

Determine the number of electrons required: According to the octet rule, one carbon monoxide (CO) molecule equals six.

Keep an eye out for the total number of bonds that are forming: In one carbon monoxide (CO) molecule, triple covalent bonds are created.

Decide on a central atom: Both atoms will be in the centre.

Make a Lewis diagram.

Carbon Monoxide’s Geometrical Shape (CO)

The carbon atom and the oxygen atom have a 180-degree binding angle. It renders carbon monoxide’s geometrical structure linear.

The valence shell electron pair repulsion (VSEPR) theory, which shows the development of a shared covalent triple bond between the carbon and oxygen atoms, can also be used to validate it.

The lone pairs, on the other hand, are drawn on the exact opposite sides of the bond formation.

The electron cloud, as well as the lone pair of electrons on both atoms, will reject each other, according to the VSEPR theory.

As a result, they will be pushed apart from one another, resulting in a linear geometry with both the carbon and oxygen atoms at 180 degrees to one another.

Carbon Monoxide Hybridization (CO)

Carbon monoxide hybridization is sp because its geometrical structure is linear. The valence shell electronic arrangement of both the carbon and oxygen atoms is depicted in the diagram below.

The carbon atom’s half-filled sp(z) hybrid orbital crosses the half-filled sp(z) hybrid orbital of the oxygen atom. This produces the first and strongest link, known as the sigma () bond.

The Valence Shell Electronic Configuration (VSEC) is an acronym for Valence Shell Electronic Configuration.

In a sidewise reaction, the half-filled 2px orbital of the carbon atom reacts and overlaps with the half-filled 2px orbital of the oxygen atom.

A weak pi () connection is formed as a result of this. Furthermore, the filled 2py orbital of the oxygen atom overlaps the 2py orbital of the carbon atom in a sideways fashion, establishing a pi () bond once more.

Two weak pi () bonds and one strong sigma () bond are formed as a result of this.

One strong and two weak covalent bonds are formed between the carbon and oxygen molecules of carbon monoxide in this way.

It may surprise you to learn that both carbon and oxygen have a single electron pair in the sp(z) orbital.

Carbon Monoxide Molecular Orbital Diagram (CO)

The energy levels for the molecular orbitals of carbon monoxide are shown in the graphic above (CO)

A molecular orbital diagram is a diagrammatic description of how chemical bonding occurs within a molecule.

It regulates how pi and sigma bonds are created inside a common covalent link, as well as their strength intensity.

Because oxygen is more electronegative than carbon, it attracts a pair of electrons that are tightly shared. As a result, the oxygen (+1) develops a partial positive charge, whereas the carbon develops a partial negative charge (-1).

Both charges are supposed to cancel each other out, leaving the carbon monoxide (CO) molecule with a neutral net overall charge.

No, because the two electrons on the carbon are lone pairs, not bonding pairs, this does not happen. A partial menial negative forms on the carbon atom as a result of this.

The idea of electronegativity states that because oxygen is more electronegative than carbon, its orbitals are more stable and have a lower energy than carbon’s.

As a result, the CO molecule has a net dipole moment, resulting in a polar molecule. You may read more about CO polarity in this article.

The bonding orbitals of the carbon and oxygen atoms are both full.

On the other hand, there are two non-bonding orbitals in existence. On the carbon side, one is present, while on the oxygen side, the other is present.


Carbon monoxide (CO) has a Lewis structure with three bonds, one of which is a strong sigma bond and the other two are weak pi bonds. Furthermore, the contribution of the lone pair of electrons contributes to the carbon monoxide (CO) molecule’s linear geometry.

It may surprise you to learn that molecular orbital theory, rather than hybridization, is a better fit for studying carbon monoxide (CO).

Misha Khatri
Misha Khatri is an emeritus professor in the University of Notre Dame's Department of Chemistry and Biochemistry. He graduated from Northern Illinois University with a BSc in Chemistry and Mathematics and a PhD in Physical Analytical Chemistry from the University of Utah.


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