CS2 Lewis structure is made up of one carbon (C) atom, and two sulfur (S) atoms. The carbon (C) atom is kept at the central position and the Sulfur (S) atom is on either side of it in the lewis diagram. In the CS2 lewis structure, there are a total of 4 lone pairs and 2 double bonds present.
Let’s see how to draw the lewis dot structure for CS2 with simple steps.
Follow some steps for drawing the Lewis dot structure for CS2
1. Count total valence electron in CS2
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 the bond formation either by donating or accepting.
To find the total valence electron in CS2, look at the periodic group of carbon and sulfur atoms.
By looking at the periodic table, we come to know carbon belongs to 14 groups and sulfur belongs to the 16th group in the periodic table. Hence, carbon has 4 valence electrons and sulfur has 6 valence electrons.
⇒ Valence electron of Sulfur = 6 [∴ Periodic group of sulfur = 16 or 6A]
⇒ Valence electron of Carbon = 4 [∴ Periodic group of carbon = 14 or 4A]
∴ Total valence electron available for drawing the CS2 lewis structure = 4 + 2*6 = 16 valence electrons [∴ CS2 molecule has one carbon and two sulfur atoms]
2. Find the least electronegative atom and placed it at center
Now we need to find which atom(Carbon or Sulfur) has the least electronegativity then place that atom in the center of lewis’s diagram.
The electronegativity of the sulfur atom is 2.58 and for the carbon atom, it is 2.55
Clearly, the Carbon atom is less electronegative than Sulfur, therefore, place it at the center of the lewis diagram and put the sulfur atoms on either side of it.
3. Connect carbon and sulfur with a single bond
In the third step, we will start to draw the skeletal structure of CS2 by connecting the outer atom (Sulfur) 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 CS2.
∴ (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(Sulfur) first to complete its octet rule.
“Octet rule show that atom is most stable when eight electrons present in its valence shell.”
So, sulfur needs 8 electrons around it for coming into the stable zone. Therefore, place the remaining valence electron around sulfur atoms first for completing their octet shell.
So, look at the above diagram and see how many valence electrons we used till now and how many are left. Each sulfur has 8 electrons(6 dot electrons + 2 electrons in a single bond), therefore, sulfur atoms completed their octets comfortably.
In the above diagram, 16 valence electrons are used(6 on each sulfur atom + 4 electrons in form of two single bonds).
So, we are left with zero valence electrons.
5. Complete central atom octet and make multiple bonds if necessary
In this step, we have to complete the central atom(Carbon) octet.
As carbon needs 8 electrons to complete its octet shell but carbon has only 4 electrons(two single bonds) around it. (Look at 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 sulfur lone pair electrons.
We will convert the one lone pair of each sulfur atom into a covalent bond.
Now look at the above structure and see if the atoms of the CS2 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 sulfur atoms also have 8 electrons, as they are connected with one double bond means 4 electrons + 4 electrons represented as dots.
Yes, both atoms(Carbon and Sulfur) have completed their octet rule comfortably as each of them has 8 electrons in the outermost shell.
Now just check the overall stability of the above CS2 Lewis structure with the help of the formal charge concept.
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 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 atom:
⇒ 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 sulfur atom
⇒ Valence electrons of sulfur = 6
⇒ Nonbonding electrons on sulfur = 4
⇒ Bonding electrons around sulfur (one double bond) = 4
∴ (6 – 4 – 4/2) = 0 formal charge on the sulfur atoms.
So, both atoms(carbon and sulfur) get a formal charge equal to zero.
Carbon disulfide (CS2) lewis structure
Therefore, the above lewis dot structure of CS2 is better, appropriate, and most stable as the overall formal charge is zero.
Also check –
- Formal charge calculator
- Lewis structure calculator
- How to draw a lewis structure?
The molecular geometry of CS2 is linear. Because the carbon (C) central atom has no lone pair and is attached to the two sulfur (S) atoms. So, there are two regions of electron density around the carbon central atom, based on VSEPR theory, it will acquire linear molecular geometry.
“A region of electron density means the group of bonding or nonbonding electrons that present around the atom.
The single bond, double bond, or even triple bond around the atom will be counted as one region”.
The electron pair around the carbon central atom will repel each other and tried 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 alinear molecular geometry because repulsion is minimum in electron pairs at this position.
Hence, the molecular geometry or shape of CS2 appears linear
The electron geometry for CS2 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 CS2 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 CS2 molecule:
- A denotes the central atom, so, carbon is the central atom in CS2 molecule A = Carbon
- X denotes the bonded atoms to the central atom, Carbon is bonded with two sulfur atoms. Therefore, X = 2
- N represents the lone pair on the central atom, as per the CS2 lewis structure, the carbon central atom has zero lone pair. Hence, N = 0
So, the AXN generic formula for the CS2 molecule becomes AX2N0or 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.
So, the molecular geometry or shape of the CS2 is linear and its electron geometry is also linear.
Hybridization of CS2
According to the VSEPR theory, a Steric number is used to determine the hybridization of an atom.
When the Steric number is equal to 2, then the hybridization of that atom is sp, and if it is equal to 3 then Sp²…..so on.
| Steric number | Hybridization |
| 2 | Sp |
| 3 | Sp² |
| 4 | Sp³ |
| 5 | Sp³d |
| 6 | Sp³d² |
Note: Steric number = Hybridization number
The steric number is simply an addition of bonded atom to the atom and a lone pair present on that atom.
The formula for finding the steric number of atoms.
According to CS2 lewis’s structure, Carbon is the central atom that has zero lone pair on it and two Sulfur atoms are attached to it.
Therefore, Steric number = 0 + 2
∴ S.N. = 2
So, two steric number means carbon has Sp hybridization in the CS2 molecule.
You can also find the steric number of the Sulfur atom. Each sulfur in the lewis dot structure of CS2 has two lone pairs on it and is attached to 1 Carbon atom.
Steric number of Sulfur = 2 + 1
= 3 is the steric number, which means each sulfur has Sp² hybridization in the CS2 molecule.
The bond angle of CS2
CS2 has a bond angle of 180º. In CS2, the carbon (C) central atom has no lone pair and is attached to two sulfur (O) atoms. Therefore, no distortion occurs around the central atom which makes it linear in shape that has a bond angle of 180º.
Also check:-How to find bond angle?
