C2Cl4 Lewis structure

C₂Cl₄ (tetrachloroethylene) has two carbon atoms and four chlorine atoms.

In C₂Cl₄ Lewis structure, there is a double bond between the two carbon atoms, and each carbon is attached with two chlorine atoms, and on each chlorine atom, there are three lone pairs.

Alternative method: Lewis structure of C₂Cl₄

Rough sketch

First, determine the total number of valence electrons

In the periodic table, carbon lies in group 14, and chlorine lies in group 17.

Hence, carbon has four valence electrons and chlorine has seven valence electrons.

Since C₂Cl₄ has two carbon atoms and four chlorine atoms, so…

Valence electrons of two carbon atoms = 4 × 2 = 8
Valence electrons of four chlorine atoms = 7 × 4 = 28

And the total valence electrons = 8 + 28 = 36

Learn how to find: Carbon valence electrons and Chlorine valence electrons

• Second, find the total electron pairs

We have a total of 36 valence electrons. And when we divide this value by two, we get the value of total electron pairs.

Total electron pairs = total valence electrons ÷ 2

So the total electron pairs = 36 ÷ 2 = 18

• Third, determine the central atom

We have to place the least electronegative atom at the center.

Since carbon is less electronegative than chlorine, assume that the central atom is carbon.

Here, there are two carbon atoms, so we can assume any one as the central atom.

Let’s assume that the central atom is left carbon.

Therefore, place carbons in the center and chlorines on either side.

• And finally, draw the rough sketch

Lone pair

Here, we have a total of 18 electron pairs. And five bonds are already marked. So we have to only mark the remaining thirteen electron pairs as lone pairs on the sketch.

Also remember that carbon is a period 2 element, so it can not keep more than 8 electrons in its last shell. And chlorine is a period 3 element, so it can keep more than 8 electrons in its last shell.

Always start to mark the lone pairs from outside atoms. Here, the outside atoms are chlorines and right carbon.

So for each chlorine, there are three lone pairs, for right carbon, there is one lone pair, and for left carbon, there is zero lone pair because all thirteen electron pairs are over.

Mark the lone pairs on the sketch as follows:

Formal charge

Use the following formula to calculate the formal charges on atoms:

Formal charge = valence electrons – nonbonding electrons – ½ bonding electrons

For left carbon atom, formal charge = 4 – 0 – ½ (6) = +1

For right carbon atom, formal charge = 4 – 2 – ½ (6) = -1

For each chlorine atom, formal charge = 7 – 6 – ½ (2) = 0

Here, both carbon atoms have charges, so mark them on the sketch as follows:

The above structure is not a stable Lewis structure because both carbon atoms have charges. Therefore, reduce the charges (as below) by converting lone pairs to bonds.

Convert a lone pair of the right carbon atom to make a new C — C bond with the left carbon atom as follows:

Final structure

The final structure of C₂Cl₄ contains two central carbon atoms linked together by a double covalent bond. In this configuration, each carbon atom satisfies the octet rule by forming two single bonds with chlorine atoms in addition to the double bond shared between the carbons. Within this layout, every chlorine atom reaches a stable octet by maintaining three lone pairs alongside its single shared bond. This arrangement represents the most stable state for the molecule because it results in a formal charge of zero for every atom involved. Consequently, this specific electronic distribution serves as the definitive and most accurate Lewis representation of tetrachloroethene (commonly known as perchloroethylene).

Next: BF₄^– Lewis structure

External video

• C2Cl4 Lewis Structure: How to Draw the Lewis Structure for (Tetrachloroethylene) – YouTube • Wayne Breslyn

External links

• https://homework.study.com/explanation/draw-the-lewis-dot-structure-for-c2cl4-tetrachloroethylene.html
• https://www.chegg.com/homework-help/questions-and-answers/lewis-structure-c2cl4-q3366366
• https://oneclass.com/homework-help/chemistry/7062379-c2cl4.en.html