# 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.

Contents

## Steps

Use these steps to correctly draw the C2Cl4 Lewis structure:

#1 First draw a rough sketch
#2 Mark lone pairs on the atoms
#3 Calculate and mark formal charges on the atoms, if required
#4 Convert lone pairs of the atoms, and minimize formal charges
#5 Repeat step 4 if needed, until all charges are minimized, to get a stable Lewis structure

Let’s discuss each step in more detail.

### #1 First draw a 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

• 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

### #2 Mark lone pairs on the atoms

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:

### #3 Calculate and mark formal charges on the atoms, if required

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.

### #4 Convert lone pairs of the atoms, and minimize formal charges

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

In the above structure, you can see that the central atom (left carbon) forms an octet. And the outside atoms (right carbon and chlorines) also form an octet. Hence, the octet rule is satisfied.

Also, the above structure is more stable than the previous structures. Therefore, this structure is the stable Lewis structure of C2Cl4.

Next: BF4 Lewis structure