# C2F4 Lewis structure

C2F4 (tetrafluoroethylene) has two carbon atoms and four fluorine atoms.

In C2F4 Lewis structure, there is a double bond between the two carbon atoms, and each carbon is attached with two fluorine atoms, and on each fluorine atom, there are three lone pairs.

Contents

## Steps

Here’s how you can easily draw the C2F4 Lewis structure step by step:

#1 Draw a rough skeleton structure
#2 Mention lone pairs on the atoms
#3 If needed, mention formal charges on the atoms
#4 Minimize formal charges by converting lone pairs of the atoms, and try to get a stable Lewis structure
#5 Repeat step 4 again if needed, until all charges are minimized

Now, let’s take a closer look at each step mentioned above.

### #1 Draw a rough skeleton structure

• First, determine the total number of valence electrons

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

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

Since C2F4 has two carbon atoms and four fluorine atoms, so…

Valence electrons of two carbon atoms = 4 × 2 = 8
Valence electrons of four fluorine 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 fluorine, 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 fluorines on either side.

• And finally, draw the rough sketch

### #2 Mention 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 both (carbon and fluorine) are the period 2 elements, so they can not keep more than 8 electrons in their last shell.

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

So for each fluorine, 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 If needed, mention formal charges on the atoms

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 fluorine 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 Minimize formal charges by converting lone pairs of the atoms

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 fluorines) 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 C2F4.

Next: IBr3 Lewis structure