Lewis structure of CCl2F2

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Lewis structure of CCl2F2
Lewis structure of CCl2F2

The Lewis structure of CCl2F2 contains four single bonds, with carbon in the center, and two chlorines and two fluorines on either side. There are three lone pairs on each chlorine atom and each fluorine atom, and the carbon atom does not have any lone pair.

Steps

By using the following steps, you can easily draw the Lewis structure of CCl2F2.

#1 Draw skeleton
#2 Show chemical bond
#3 Mark lone pairs
#4 Calculate formal charge and check stability (if octet is already completed on central atom)

Let’s one by one discuss each step in detail.

#1 Draw skeleton

In this step, first calculate the total number of valence electrons. And then, decide the central atom.

  • Let’s calculate the total number of valence electrons

We know that… carbon is a group 14 element, and both chlorine and fluorine are the group 17 elements. Hence, carbon has four valence electrons, and both chlorine and fluorine have seven valence electrons.

Now CCl2F2 has one carbon atom, two chlorine atoms, and two fluorine atoms.

So the total number of valence electrons = valence electrons of carbon atom + (valence electrons of chlorine atom × 2) + (valence electrons of fluorine atom × 2)

Therefore, the total number of valence electrons = 4 + 14 + 14 = 32

  • Now decide the central atom

The atom with the least electronegative value is placed at the center. By looking at the periodic table, we get the electronegativity values for carbon, chlorine, and fluorine as follows:

Electronegativity value of carbon = 2.55
Electronegativity value of chlorine = 3.16
Electronegativity value of fluorine = 3.98

Obviously, carbon is less electronegative than chlorine and fluorine. Hence, assume that carbon is the central atom.

So now, put carbon in the center and chlorines and fluorines on either side. And draw the rough skeleton structure for the Lewis structure of CCl2F2 something like this:

Skeleton structure for Lewis structure of CCl2F2

#2 Show chemical bond

Place two electrons between the atoms to show a chemical bond. Since carbon is surrounded by two chlorines and two fluorines, use eight electrons to show four chemical bonds as follows:

Four chemical bonds shown between atoms

#3 Mark lone pairs

As calculated earlier, we have a total of 32 valence electrons. And in the above structure, we have already used eight valence electrons. Hence, twenty-four valence electrons are remaining.

Two valence electrons represent one lone pair. So twenty-four valence electrons = twelve lone pairs.

Note that both (carbon and fluorine) are the period 2 elements, so they can not keep more than 8 electrons in their last shell. And chlorine is a period 3 element, so it can keep more than 8 electrons in its last shell.

Also, make sure that you start marking these lone pairs on outside atoms first. And then, on the central atom.

The outside atoms are chlorines and fluorines, so each chlorine and each fluorine will get three lone pairs. And the central atom (carbon) will not get any lone pair, because all twelve lone pairs are used.

So the Lewis structure of CCl2F2 looks something like this:

Lone pairs marked on Lewis structure of CCl2F2

In the above structure, you can see that the octet is completed on the central atom (carbon), and also on the outside atoms. Therefore, the octet rule is satisfied.

After completing the octet, one last thing we need to do is, calculate the formal charge and check the stability of the above structure.

#4 Calculate formal charge and check stability

The following formula is used to calculate the formal charges on atoms:

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

Collect the data from the above structure and then, write it down below as follows:

  • For carbon atom

Valence electrons = 4
Nonbonding electrons = 0
Bonding electrons = 8

Formal charge = 4 – 0 – ½ (8) = 0

  • For each chlorine atom

Valence electrons = 7
Nonbonding electrons = 6
Bonding electrons = 2

Formal charge = 7 – 6 – ½ (2) = 0

  • For each fluorine atom

Valence electrons = 7
Nonbonding electrons = 6
Bonding electrons = 2

Formal charge = 7 – 6 – ½ (2) = 0

Mention the formal charges of atoms on the structure. So the Lewis structure of CCl2F2 looks something like this:

Formal charges are calculated, and got the stable Lewis structure of CCl2F2

In the above structure, you can see that the formal charges of all atoms are zero. Therefore, this is the stable Lewis structure of CCl2F2.

And each horizontal line drawn in the above structure represents a pair of bonding valence electrons.

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Deep

Rootmemory.com was founded by Deep Rana, who is a mechanical engineer by profession and a blogger by passion. He has a good conceptual knowledge on different educational topics and he provides the same on this website. He loves to learn something new everyday and believes that the best utilization of free time is developing a new skill.

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