Carbon dioxide (CO2) lewis dot structure, molecular geometry or shape, electron geometry, bond angle, hybridization, formal charge
Carbon dioxide is made up of one carbon and two oxygen having the chemical formula CO2. It is a combustible gas resulting from the oxidation of carbon.
In this article, we will discuss Carbon dioxide (CO2) lewis structure, molecular geometry or shape, electron geometry, bond angle, hybridization, polar or nonpolar, etc.
At room temperature, carbon dioxide normally acts as gas but at high pressure, it turned into liquid. CO2 can be an environmental disaster due to its heat-absorbing properties.
|Name of Molecule||Carbon dioxide (CO2)|
|Molecular geometry or shape of CO2||Linear|
|Electron geometry of CO2||Linear|
|Total Valence electron in CO2||16|
|Total Formal charge in CO2||0|
How to draw lewis structure of CO2 (Carbon dioxide)?
CO2 Lewis structure is made up of one carbon (C) atom, and two oxygen (O) atoms. The carbon (C) atom is kept at the central position and the Oxygen (O) atom is on either side of it in the lewis diagram. In the CO2 lewis structure, there are a total of 4 lone pairs present.
A lewis structure helps us to know how electrons are arranged around individual atoms in a molecule.
Let’s see how to draw the lewis structure for CO2 with simple steps.
Follow some steps for drawing the Lewis dot structure for CO2
1. Count total valence electrons in CO2
As we know, the lewis diagram is all about representing the valence electron of atoms within the molecule. Valence electrons are the outermost electron of an atom that can participate in bond formation either by donating or accepting.
To find the total valence electron in CO2, look at the periodic group of carbon and oxygen atoms.
By looking at the periodic table, we come to know carbon belongs to 14 groups and oxygen belongs to the 16th group in the periodic table. Hence, carbon has 4 valence electrons and oxygen has 6 valence electrons.
⇒ Valence electron of Oxygen = 6 [∴ Periodic group of oxygen = 16 or 6A]
⇒ Valence electron of Carbon = 4 [∴ Periodic group of carbon = 14 or 4A]
∴ Total valence electron available for drawing the CO2 lewis structure = 4 + 2*6 = 16 valence electrons [∴ CO2 molecule has one carbon and two oxygen atoms]
2. Find the least electronegative atom and placed it at center
Now we need to find which atom(Carbon or oxygen) has the least electronegativity and then place that atom in the center of lewis’s diagram.
The electronegativity of the oxygen atom is 3.44 and for the carbon atom, it is 2.55
Clearly, the Carbon atom is less electronegative than Oxygen, therefore, place it at the center of the lewis diagram and put the oxygen atoms on either side of it.
3. Connect carbon and oxygen with a single bond
In the third step, we will start to draw the lewis structure of CO2 by connecting the outer atom (Oxygen) to the central atom (Carbon) with the help of a single bond.
By looking at the above diagram, we come to know that two single bonds are used that contain 4 electrons. (A single bond means 2 electrons)
So, we used 4 electrons from a total of 16 valence electrons that are available for drawing the Lewis structure of CO2.
∴ (16 – 4) = 12 valence electrons
Now we are left with 12 valence electrons.
4. Placed remaining valence electrons around the outer atom
As we are left with 12 valence electrons and we have to place these electrons around the outer atom(Oxygen) first to complete its octet rule.
“Octet rule show that atom is most stable when eight electrons present in its valence shell.”
So, oxygen needs 8 electrons around it for coming into the stable zone. Therefore, place the remaining valence electron around oxygen first for completing its octet shell.
So, look at the above diagram and see how many valence electrons we used till now and how many are left. Each oxygen has 8 electrons(6 dot electrons + 2 electrons in a single bond), therefore, oxygen atoms completed their octets comfortably.
In the above diagram, 16 valence electrons are used(6 on each oxygen atom + 4 electrons in form of two single bonds).
So, we are left with zero valence electrons.
5. Complete the central atom octet and make a covalent bond if necessary
In this step, we have to complete the central atom(Carbon) octet for its stability.
As carbon needs 8 electrons to complete its octet shell but carbon has only 4 electrons(two single bonds) around it. (Look at the 4th step structure).
Therefore, the carbon atom needs 4 more electrons to complete its octet. Also, we have no extra valence electrons left for completing the octet of carbon.
So, to overcome this problem, we will take the help of oxygen lone pair electrons.
We will convert the one lone pair of each oxygen atom into a covalent bond as shown in the figure given below.
Now look at the above structure and see if the atoms of the CO2 molecule, completed their octet or not.
The carbon central atom has 8 electrons in its valence shell, since, it connected with 2 double bonds. [∴ 1 double bond means 4 electrons].
Also, both oxygen also has 8 electrons, as they are connected with one double bond means 4 electrons + 4 electrons represented as dots.
Yes, both atoms(Carbon and oxygen) have completed their octet rule comfortably as each of them has 8 electrons in the outermost shell.
Now just check the stability of the above structure with the help of the formal charge concept.
6. Check the stability of CO2 lewis structure with the help of a formal charge concept
“The lesser the formal charge on atoms, the better is the stability of the lewis structure.”
To calculate the formal charge on an atom. Use the formula given below-
We will calculate the formal charge for the 5th step structure.
For carbon atoms:
- Valence electrons of carbon = 4
- Nonbonding electrons on carbon = 0
- Bonding electrons around carbon (two double bonds) = 8
- ∴ (4 – 0 – 8/2) = 0 formal charge on the central carbon atom.
For oxygen atom
- Valence electrons of oxygen = 6
- Nonbonding electrons on oxygen = 4
- Bonding electrons around oxygen (one double bond) = 4
- ∴ (6 – 4 – 4/2) = 0 formal charge on the oxygen atom.
So, both atoms(carbon and oxygen) get a formal charge equal to zero.
Carbon dioxide (CO2) lewis structure
Therefore, the above lewis structure of CO2 is better, appropriate, and most stable as the overall formal charge is zero.
Also check –
What is the electron and molecular geometry of CO2 (Carbon dioxide)?
The molecular geometry of CO2 is Linear. It has a linear geometry arrangement like O=C=O. The molecule (CO2) has 2 electron domains, resulting in a linear electron domain geometry.
CO2 molecular geometry or shape
Molecular geometry is an arrangement of atoms in a molecule. CO2 lewis structure can give us an approximate measure of its molecular shape but to determine the precise molecular geometry of CO2, we need to look at the VSEPR theory.
VSEPR theory predicts the shape of the molecule by taking the measure of repulsion between electron pairs in the valence shell.
Now the question arises why the molecular geometry or shape of CO2 is linear?
- The molecular geometry of CO2 is linear. The central atom carbon (C) is bonded with two oxygen (O) atoms via a double bond and it has zero lone pair.
- Based on VSEPR theory, electron pairs around the central carbon atom are going to repel each other, so, those two oxygen atoms are going to push far as much as they can to either side of the central atom and that makes, CO2 a linear molecule.
As you see in the above figure, the bond pair on both sides of the carbon central atom are repelling each other, because of this, both side oxygen atoms are pushed far away from each other in a straight line, therefore, the overall molecular geometry of CO2 will be linear.
VSEPR theory only predict the geometry based on electron pair that are around the Central atom.
It doesn’t matter how many lone pair are on outer atoms, only thing is matter around the central atom.
So, in a CO2 molecule, the carbon central atom has no lone pair, and it is attached with only bonding pairs, hence, for keeping the repulsive force least generated by the bonding pairs around the central atom, CO2 acquires the linear molecular geometry or shape.
The electron geometry for CO2 is also linear. Since, the central Carbon (C) atom is surrounded by 2 regions of electron density, according to VSEPR theory, “the maximum distance two regions of electron density can get away from affords a geometry called Linear”.
We can also find the electron and molecular geometry of CO2 using the AXN method and VSEPR chart.
AXN is a simple formula that represents the number of the bonded atom and lone pair on the central atom to predict the shape of the molecule using the VSEPR chart.
According to AXN method-
- A represents the central atom.
- X represents the bonded pair of electrons to the central atom.
- N represents the lone pair of electrons on the central atom
AXN notation for CO2 molecule:
- A denotes the central atom, so, carbon is the central atom in CO2 molecule A = Carbon
- X denotes the bonded atoms to the central atom, Carbon is bonded with two oxygen atoms. Therefore, X = 2
- N represents the lone pair on the central atom, as per the CO2 lewis structure, the carbon central atom has zero lone pair. Hence, N = 0
So, the AXN generic formula for the CO2 molecule becomes AX2N0 or AX2.
According to the VSEPR chart, if any molecule has the AX2 formula then the molecule geometry of that molecule is linear and electron geometry is also linear.
Look at the VSEPR chart below to clear your doubts.
The VSEPR chart confirms that the molecular geometry or shape of a molecule with an AX2 generic formula is identical to its electron pair geometry i.e., linear, as we already noted down for carbon dioxide (CO2).
Hybridization of CO2
The central carbon in the CO2 molecule is sp hybridized. The electronic configuration of C is 1s22s22p2 which cannot sufficiently form bonds with oxygen atoms.
So, one 2s electron of carbon shifts to a 2p orbital. The valence shell configuration becomes 2s12px12py12pz1. The 2s and 2px orbital combine to form 2 sp hybrid orbitals while the py and pz orbitals stay unhybridized.
Conversely, O has an electronic configuration of 1s22s22p4. It also hybridizes by using its 2s and two of the three 2p orbitals to form three sp2 hybrid orbitals.
The pz orbital in CO2 stays unhybridized. Two sp2 hybrid orbitals of oxygen each have a lone pair of electrons which appear as un-bonded pairs on each O atom in CO2.
Oxygen uses the third sp2 hybrid orbital to form a sigma bond with C while the unhybridized pz orbital of O forms a pi bond with the p orbital of C.
There are two sigma bonds and two pi bonds in CO2 which facilitates the symmetrical arrangement and linear geometry of the molecule further endorsing the non-polar nature of carbon dioxide.
The bond angle of CO2
CO2 has a bond angle of 180º. In CO2, the carbon (C) central atom has no lone pair and is attached to two oxygen (O) atoms. Therefore, no distortion occurs around the central atom which makes it linear in shape that has a bond angle of 180º.
As we already discussed the molecule (CO2) is an AX2 type molecule. According to VSEPR, the AX2 type molecule has a linear shape signifies that all the bonded atoms lie in a straight line thus they form a mutual bond angle of 180°.
Also check:- How to find bond angle?
Carbon dioxide polarity: Is CO2 polar or nonpolar?
Well, we know the polar molecule has some dipole moment because of unequal distribution of charges whereas the non-polar molecule has an equal distribution of charges that cause zero dipole moment because they cancel out each other due to the symmetrical shape of the molecule.
Is Carbon dioxide (CO2) polar or non-polar? CO2 is a non-polar molecule because it contains two bonds(C=O) that are arranged symmetrically. Due to this, the dipole moment generated on both sides along C=O cancels out each other making it a non-polar molecule.
Read in detail –
How many lone pairs are present in the lewis structure of CO2?
Lone pairs are those represented as dots in the lewis diagram that do not take part in the formation of bonds and are also called nonbonding electrons.
By looking at the lewis structure of CO2, we see there are 8 dot electrons are present(4 dot electrons on each oxygen), which means, a total of 4 lone pairs are present in the lewis structure of CO2. [∴ 2 dot electrons means 1 lone pair].
How many valence electrons are available for drawing the CO2 lewis dot structure?
⇒ Valence electron available for Carbon = 4
⇒ Valence electron available for Oxygen = 6
∴ Total Valence electron available for CO2 lewis dot structure = 4 + 2×6 = 16 electrons
Why CO2 is non-polar?
CO2 is non-polar because of its symmetrical geometry and the dipole moment generated along with the C=O bond also canceled out each other as the molecular shape of CO2 is linear and it has Sp hybridization with a bond angle of 180º which makes it a highly symmetrical molecule.
Also, no lone pair is present on the central atom in the CO2 lewis structure which helps to avoid distortions in the molecule.
Why the molecular geometry of CO2 is linear?
The molecular geometry of CO2 is linear. Because the carbon (C) central atom has no lone pair and is attached to the two oxygen (O) atoms. So, there are two regions of electron density around the carbon central atom, based on VSEPR theory, it will acquire linear molecular geometry.
The electron pair around the carbon central atom will repel each other and try to go far from each other, they will take the position where repulsion becomes minimum between them.
According to the VSEPR theory, the central atom with two regions of electron density adopts a linear molecular geometry because repulsion is minimum in electron pairs at this position.
Hence, the molecular geometry or shape of CO2 appears linear.
Why electron and molecular geometry of CO2 are same?
Two types of geometry can be predicted with the help of VSEPR theory- (a). Electron geometry (b). Molecular geometry
Electron geometry considers all electrons(Bonding and Lone pair electrons) whereas molecular geometry considers only Bonding atoms to determine the geometry of any molecule.
As we know, the molecular geometry of CO2 is linear and electron geometry is also linear.
Since there is no lone pair present on the central atom in the CO2 lewis dot structure. Therefore, both molecular and electron geometry predict the shape of CO2 with the help of bonded pair of electrons.
Hence, the molecular geometry and electron geometry of CO2 is the same.
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- The total valence electron available for drawing the CO2 lewis structure is 16.
- The molecular geometry of CO2 is linear.
- In the CO2 lewis structure, there is a total of 4 lone pairs present. Two lone pairs on each oxygen atom.
- The electron geometry of CO2 is also linear.
- The bond angle of CO2 is 180º. Since it is linear in shape with an arrangement like that O=C=O.
- Two types of hybridization in CO2 – Sp, and Sp2.
- The net dipole moment of CO2 is zero.
- CO2 is a non-polar molecule.
- The overall formal charge in CO2 is zero.
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