The carbon tetrachloride (CCl4) Lewis structure is made up of one carbon (C) atom that is situated at the middle position and four chlorine (Cl) atoms that are at the surrounding position in the lewis diagram. The total lone pair present in the CCl4 lewis dot structure is 12.
To draw the stable CCl4 lewis structure, we have to represent the valence electron of each atom within a molecule.
Steps for drawing the lewis dot structure of CCl4
1. Count total valence electron in CCl4
In the first step of every lewis diagram, we need to know how many valence electrons are present in a molecule. For finding the valence electron in CCl4, we have to know the periodic group number of Carbon and chlorine.
The periodic group of carbon is 14 or 4A and for chlorine, it is 17 or 7A. Hence carbon has 4 valence electrons present in its outermost shell and chlorine has 7 valence electrons present in its outermost shell.
∴ Total valence electron available for drawing the lewis structure of CCl4 = 4 + 7*4 = 32 electrons.
2. Find the least electronegative atom and placed it at center
In this step, We will find the central atom to place in the lewis diagram by determining the least electronegative atom in between Carbon or Chlorine.
∴ The electronegativity for the Carbon atom is 2.55, and for the chlorine atom, it is 3.16.
Hence, carbon is a less electronegative atom than chlorine. Therefore, carbon is placed in the central position, and chlorine atoms are spaced evenly around it.
3. Connect carbon and chlorine with a single bond
Here, we will make the CCl4 skeletal structure by connecting each chlorine atom to carbon with the help of a single bond.
Now look at the above structure and find how many valence electrons we used till now.
In the above structure, 4 single bonds are used for connecting chlorine atoms to a central carbon atom and 1 single bond contains 2 electrons.
Therefore, 4 single bonds mean 8 electrons are used in the above structure from a total of 32 valence electrons available for the CCl4 lewis structure.
∴ (32 – 8) = 24 valence electrons
So, we are left with 24 valence electrons more.
4. Complete the octet of outer atoms first
After the third step, we have a total of 24 valence electrons left and we need to put these valence electrons around the chlorine atoms first for completing their octet.
Chlorine needs 8 electrons in its valence shell to complete its octet. So, put the remaining valence electrons around each chlorine atom till they complete their octet.
Each chlorine atom in the above structure completed its octet, since, all have 8 electrons(6 represented as dots + 2 electrons in a single bond) in their valence shell.
5. Complete the octet of the central atom
Carbon is the central atom and it needs 8 electrons in the valence shell to complete its octet. Look at the 4th step structure, the Carbon atom already has 8 electrons because of 4 single bonds that are attached to it.
Now just check the formal charge for the above structure to get its stability.
6. Check the stability with the help of a formal charge concept
“The lesser the formal charge on atoms, the better is the stability of the lewis diagram.”
To calculate the formal charge on an atom. Use the formula given below-
What are the electron and molecular geometry of CCl4?
The molecular geometry of CCl4 is tetrahedral and its electron geometry is also tetrahedral because as per VSEPR theory, molecular shape considers only bond pairs while electron geometry considers bonded atoms as well as lone pairs present on the central atom.
In CCl4, the carbon (C) atom has attached to four bonded atoms, and it contains no lone pair which means, there are four regions of electron density around the carbon central atom.
“The VSEPR theory states that the electron regions around an atom spread out to make each region is as far from the others as possible.”
So, these electron pairs around the carbon (C) central atom tend to go far from each other and stabilized where the repulsion remains minimum between them.
These electron pairs point towards the corner of the tetrahedron with respect to the minimization of electron pair-electron pair repulsion.
When there is no lone pair, then, central atom with four region of density adopt a tetrahedral structure because repulsion is minimum in electron pairs at this position.
Hence, the final molecular geometry of CCl4 appears like a regular tetrahedron with a bond angle ∠Cl−C−Cl=109.5°.
Molecular geometry is the three-dimensional arrangement of atoms in a molecule.
Let’s see how to find CCl4 molecular geometry and its bond angle.
Follow three steps to find CCl4 molecular geometry
1. Find the Number of lone pairs present on the central atom of the CCl4 lewis structure
As per the CCl4 lewis structure, carbon is the central atom that has no lone pair present on it because carbon completes its octet with the help of 4 single bonds.
Or you can determine the lone pair in CCl4 by using the simple formula.
∴ L.P = (V.E. – N.A.)/2
where L.P. = Lone pair on the central atom
⇒ V.E. = valence electron of that central atom
⇒ N.A. = Number of atoms attached to that central atom
So, the valence electron of Carbon is 4, and the number of the attached atom to Carbon is also 4.
Put these values in the given formula-
∴ (4 – 4)/2
= 0 is the lone pair present on the central atom(carbon).
2. Find the hybridization number of CCl4
For finding the hybridization number of CCl4, Use the given below formula.
∴ H = N.A. + L.P.
where H = hybridization number
⇒ N.A. = Number of atoms attached to the central atom
⇒ L.P. = lone pairs on that central atom
According to the CCl4 lewis structure, Carbon is the central atom, and the number of the attached atoms to carbon is 4 with the zero lone pair on It.
∴ H = 4 + 0
= 4 is the hybridization number of CCl4
Hence, Sp³ is the hybridization of CCl4.
3. Use VSEPR theory or AXN method to determine CCl4 molecular shape/geometry
According to the VSEPR (Valence shell electrons repulsion) theory, if any molecule has 0 lone pair and Sp³ hybridization then the molecular and electron geometry of that molecule is tetrahedral.
Hence, the molecular geometry of CCl4 is tetrahedral.
CCl4 molecular geometry or shape
Another method we have is AXN for determining the molecular geometry of CCl4.
Let’s see how to use this method.
A represents the central atom.
X represents the bonded atoms to the central atom.
N represents the lone pairs on the central atom
As per the CCl4 lewis dot structure, carbon is the central atom that has 4 bonded atoms and 0 lone pairs on it.
Hence, the formula of CCl4 becomes AX4.
According to the VSEPR chart, if any molecule represents the AX4 generic formula then the molecule and electron geometry of that molecule is tetrahedral.
The bond angle of CCl4
The bond angle of CCl4 is 109.5º. because electrons around carbon will repel each other giving molecular geometry of CCl4 tetrahedral. Hence, its bond angle is 109.5º approx.
Is CCl4 polar or nonpolar? CCl4 is a non-polar molecule due to its symmetrical structure but the four bonds of CCl4 are polar because of the electronegativity difference between carbon (C) and chlorine (Cl).
Let’s understand whether CCl4 is polar or non-polar in detail.
Three factors that indicate the polarity of CCl4
1. Electronegativity:
Electronegativity of atoms shows its tendency to attract electrons to itself. The greater the difference in electronegativity between atoms higher is the polarity between those atoms. The electronegativity of carbon is 2.5 and for chlorine, it is 3.0. Hence it results in the polar covalent bond.
But the bond polarity between all carbon and chlorine(C-Cl) is canceled due to the CCl4 symmetric tetrahedral shape.
Therefore, the CCl4 molecule becomes non-polar in nature because symmetry cancels out the individual polar vectors.
2. Dipole moment
Dipole moment ensures the strength of polarity between carbon and a chlorine atom. The net dipole moment of CCl4 is zero because opposite bond moments cancel out each other.
As chlorine is more electronegative than carbon. Therefore, chlorine attracts electrons towards itself. Hence, the dipole is generated between the Carbon and Chlorine atom.
As you see in the above diagram, a dipole is generated between carbon and chlorine atoms. And the direction of all dipoles is the same from carbon to chlorine and at an equal distance.
As a result, equal charges are distributed in all directions.
So, they cancel each other dipole moment making CCl4 non-polar in nature.
3. Geometrical or molecular shape:
As we know molecular geometry of CCl4 is tetrahedral and all four bonds(C-Cl) are symmetrical with equal charge distribution making it easier to cancel out the dipole moment.
Also, there is no lone pair present on the central atom in the CCl4 lewis structure as a result no distortion occurs.
Therefore, the symmetrical nature of CCl4 ensures that all dipole moments are canceled out making CCl4 non-polar in nature.
Hence all these factors show why Carbon tetrachloride (CCl4) is nonpolar.
FAQ
How many lone pairs are present in the CCl4 lewis structure?
There is no lone pair on the carbon central atom but each outer atom(chlorine) has 3 lone pairs. Hence, (4 chlorine atoms × 3) = a total of 12 lone pairs present in the CCl4 lewis structure.
How many valence electrons are available for the CCl4 Lewis structure?
⇒ Valence electrons in Carbon = 4
⇒ Valence electrons in Chlorine = 7
∴ Total valence electrons in CCl4 Lewis structure = 4 + 7(4) = 32 electrons
Why is CCl4 non-polar but its four bonds are polar?
As we discussed, four bonds of CCl4 are polar but the whole molecule is non-polar because the dipole moment generated in between carbon and chlorine canceled out due to the symmetrical tetrahedral shape of CCl4.
Also, there is no lone pair present on the central atom in the CCl4 lewis structure which ensures that the molecular geometry of CCl4 is symmetrical with no distortion occurring in it.
It is non-flammable and doesn’t dissolve in water quickly.
It has a sweet smell and odor like Chloroform.
It is non-combustible.
CCl4 has a boiling point of 76.72 °C and a melting point of −22.92 °C.
It has a Tetragonal coordination geometry.
It is used as a solvent for halogenation and as an agricultural fumigant.
It is used as a fire extinguisher.
For the detection of neutrinos.
In the manufacturing of various chemicals.
It is used in stamp collecting and to reveal watermarks on postage stamps.
Summary
It’s time for the quick revision of the CCl4 Lewis structure, molecular geometry, and other aspects which we have discussed in this article.
The total valence electron available for the CCl4 lewis structure is 32.
The carbon tetrachloride lewis structure is made up of one carbon atom that is situated at the middle position and four chlorine atoms that are at the surrounding position.
CCl4 molecular geometry is tetrahedral and its electron geometry is also tetrahedral.
The bond angle of CCl4 is 109.5º.
In CCl4, the hybridization is, Sp3.
In the CCl4 lewis dot structure, a total of 12 lone pairs and 4 bond pairs are present.
CCl4 is nonpolar in nature but its bond is polar.
The net dipole moment of Carbon tetrachloride is 0.
