Is CO2 an Ionic or a Covalent Compound?

Carbon Dioxide’s molecular molecule has the chemical formula CO2. CO2 is one of the most important chemicals, and we have known it since we were children.

The role of CO2 in respiration is well-known. Aside from that, because it is a greenhouse gas, we also recognise its significance in climate change. Not only that, but when we study the carbon cycle and plant photosynthesis, we learn about carbon dioxide.

To make matters worse, who hasn’t heard of dry ice? CO2 in its solid state, which we use as a refrigerant.

You might be asking whether CO2 is an ionic or a covalent chemical because of the type of its bonding.

So, in today’s topic, we’ll talk about Carbon Dioxide and whether it’s ionic or covalent.

When the electronegativity difference between bound atoms is smaller than 1.8-2, a compound is said to be covalent. Because the difference between C and O in a CO2 molecule is roughly 0.89, we can term it a covalently bonded molecule.

Aside from that, the carbon atom shares four electron pairs with oxygen in each C and O bond, making a double bond. Both C and O achieve octet completion this way. In the second period, both oxygen and carbon are present, resulting in the noble gas Neon’s outermost shell structure.

The previous explanation only scratches the surface of the subject we’ve been discussing. Let’s take a closer look at it:

Let’s have a look at some interesting facts about the famous molecular composition first.

The molecular weight of CO2 is approximately 44.009 g/mol. It’s acidic, yet it’s not poisonous. It has a colourless, odourless gaseous appearance and can dissolve in water to generate carbonic acid (H2CO3).

This compound can be produced and manufactured in a variety of ways. A variety of chemical processes are visible here that lead to the creation of this product:

CaCO3   —->    CaO   +   CO2

CH4   +   2O2   —–>  CO2  +   2H2O

CaCO3   +   2HCl   —–>   CaCl2   +   H2CO3 – (I)   

 H2CO3   —–>   CO2    +    H2O – (ii)

Chemical Adhesion

We must first understand the type of chemical bonding within the molecule before we can evaluate whether CO2 is ionic or covalent. To do so, we must first examine chemical bonds, their types, and how they are produced in order to have a complete understanding.

One of the most important components of chemistry is chemical bonding. It is concerned with the attraction of atoms to interact with one another and form various molecular compositions.

The nucleus of an atom is surrounded by electrons, which are negatively charged subatomic particles. The electrons in the outermost shell, commonly known as valence electrons, have a proclivity to participate in bond formation, resulting in a variety of products.

The numerous forms of chemical bonding are discussed in this chapter. However, we will limit our study in this essay to two major types: ionic and covalent.

Ionic Coupling

Ionic bonds are created when an atom of a comparably electropositive element donates electrons to an atom of a comparatively electronegative element.

As a result, while one atom loses an electron(s), the other receives one (s). There is the production of a positively charged cation and a negatively charged anion, which are attracted to each other by electrostatic forces.

This type of connection is most commonly seen in a molecule made up of a metal and a non-metallic element.

Note: Chemical bond formation is usually how elements get their octet configuration.

The Covalent Bond is a type of chemical bond.

Covalent bonds are produced via the electron sharing process, in which atoms of the same or different elements combine to share electron pairs.

A single bond formed between two constituent atoms inside a molecule when one valence electron pair is shared, a double bond when two pairs are shared, and a triple bond when three pairs are shared.

Although there are certain outliers, all of the involved atoms achieve octet configuration.

The atoms sharing electrons and creating a covalent bond are depicted below.

The concept of polarity is used in covalent bonding.

Covalent bonds are classified as polar or nonpolar based on electronegativity differences. Ionic bonds already have charged atoms.

As a result, electronegativity is the most important factor in defining the type of covalent bonds.


An element’s electronegativity is one of its chemical properties. It is represented by the symbol and is defined as an atom’s proclivity to attract negatively charged electrons to itself.

We can simply get the values for each element in the periodic table using the Pauling Electronegativity chart.

When we’re trying to figure out whether a molecule is polar or nonpolar, we’ll need this diagram.

A nonpolar covalent bond is defined as one in which the electronegativity difference between two atoms in a bond is less than 0.4-0.5, according to the generalised definition.

We term a bond polar covalent when the electronegativity difference is between 0.5 and 1.8 (typically between 0.4 and approximately 2).

Anything above that is referred to as ionic.

Electronegativity Difference Bond Type
<0.4,0.5Nonpolar Covalent
0.51.8,2Polar Covalent

The following are some more factors that can influence the covalent nature of bond formation:

Ionization Energy at a Maximum

While electronegativity refers to an atom’s ability to gain electrons, ionisation energy refers to the amount of energy required to remove an electron from any isolated (typically gaseous) atom or ion.

The periodic table can be used to derive the ascending or descending sequence of ionisation energy based on the atoms’ behaviour.

A high ionisation energy means that more energy is required or that removing an electron is difficult.

As a result, atoms of such elements cannot easily shed electrons to produce positively charged ions, which are required for the creation of an ionic connection within a molecule.

As a result, in those specific circumstances, we will have covalent bonding.

Affinity for Electrons

Another attribute of an atom is electron affinity, which refers to its ability to accept negatively charged electrons.

It is the measurement of the potential energy change that occurs when an atom changes from a neutral state to an anion (negatively charged ion).

Covalent bonds are formed when the atoms’ electron attraction affinities are nearly identical.

This type of bond is primarily produced amongst non-metals.

When one is a metal and the other is a non-metal, ionic bonding form (electron affinities are different in those cases).

Electron Number of Valence

In the case of the CO2 molecule,

An O atom’s electrical configuration is 1s2 2s2 2p4.

A C atom’s electrical configuration is 1s2 2s2 2p2.

Carbon now contains four electrons in its outermost or valence shell, or a half octet. It must either gain or lose four electrons to attain octet configuration.

This is not scientifically supported because it will cause the ion to become unstable. As a result, because the carbon atom cannot establish an ionic bond, C must share electrons with the two oxygen atoms to complete the octet.

Oxygen is also a member of the chalcogen family, belonging to group 16. The elements in the later groupings (15,16,17) are all connected to the creation of covalent bonds.

Aside from that, carbon’s first ionisation energy is 1086.5 kJ/mol, while oxygen’s is 1313.9 kJ/mol.

(Remember, we’re talking about neutral atomic species, hence 1st molar ionisation energies are provided here.) Both of these numbers are extremely high.

Let’s have a look at CO2’s Lewis Structure:

We may conclude that (II) is the correct Lewis Structure configuration for CO2 because the octet fulfilment of C has not occurred in (I), and we can also get to this conclusion after measuring formal charge values.

In a carbon dioxide molecule, the C atom creates two double covalent bonds, one with each of the O atoms.


Let’s look at the polarity of the bond creation now:

Carbon has an electronegativity value of 2.55, while O has an electronegativity value of roughly 3.44, according to the Pauling electronegativity chart.

3.44 − 2.55 = 0.89 is the difference.

Each carbon and oxygen link is polar covalent in nature (C=O), according to the table above.

CO2, on the other hand, is linear, and the electric dipoles cancel out, leaving us with a net dipole of zero. As a result, it’s a nonpolar molecule.


CO2, or carbon dioxide, is one of the most important gaseous gases with numerous applications in a variety of sectors.

Although it is a nonpolar molecule, it is a covalent complex with two double covalent polar links.

CO2 is a linear molecule that is researched in chemistry because of its diverse role and influence in our daily lives.

Good luck with your studies!

Read more: Is Aluminum a Good Conductor of Electricity?

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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