Lewis structure of C6H6

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Lewis structure of C6H6
Lewis structure of C6H6 | Image: Root Memory

The Lewis structure of C6H6 contains three double bonds and nine single bonds, with six carbons in the center, and each carbon is attached with one hydrogen. Both hydrogen atom and carbon atom do not have any lone pair.

Steps

By using the following steps, you can easily draw the Lewis structure of C6H6.

#1 Draw skeleton
#2 Show chemical bond
#3 Mark lone pairs
#4 Complete octet on central atom
#5 Calculate formal charge and check stability

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 hydrogen is a group 1 element. Hence, carbon has four valence electrons and hydrogen has one valence electron.

Now C6H6 has six carbon atoms and six hydrogen atoms.

So the total number of valence electrons = (valence electrons of carbon atom × 6) + (valence electrons of hydrogen atom × 6)

Therefore, the total number of valence electrons = 24 + 6 = 30

  • Now decide the central atom

We can not assume hydrogen as the central atom, because the central atom is bonded with at least two other atoms. And hydrogen has only one electron in its last shell, so it can not make more than one bond.

Therefore, choose carbon as the central atom.

But there are six carbon atoms in C6H6. Hence, we can assume any one as the central atom. Let’s assume that top carbon is the central atom.

So now, put six carbons in the center and six hydrogens on either side. And draw the rough skeleton structure for the Lewis structure of C6H6 something like this:

Skeleton structure for Lewis structure of C6H6 | Image: Root Memory

#2 Show chemical bond

Place two electrons between the atoms to show a chemical bond. Since six carbons are surrounded by six hydrogens, use twenty-four electrons to show twelve chemical bonds as follows:

Twelve chemical bonds shown between atoms | Image: Root Memory

#3 Mark lone pairs

As calculated earlier, we have a total of 30 valence electrons. And in the above structure, we have already used twenty-four valence electrons. Hence, six valence electrons are remaining.

Two valence electrons represent one lone pair. So six valence electrons = three lone pairs.

Note that carbon is a period 2 element, so it can not keep more than 8 electrons in its last shell. And hydrogen is a period 1 element, so it can not keep more than 2 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 hydrogens, left carbons, right carbons, and bottom carbon. But hydrogen can not keep more than 2 electrons in its last shell. Hence, don’t mark the lone pairs on hydrogen.

So two left carbons and one right carbon will get one lone pair. And the remaining carbon atoms will not get any lone pair, because all three lone pairs are used.

Now draw the Lewis structure of C6H6 something like this:

Lone pairs marked on Lewis structure of C6H6 | Image: Root Memory

In the above structure, you can see that the octet is completed on outside atoms. But, the central atom (top carbon) doesn’t form an octet.

So in the next step, we have to complete the octet on the central atom.

#4 Complete octet on central atom

Remember that carbon is a period 2 element, so it can not keep more than 8 electrons in its last shell.

Now top carbon already has six valence electrons. Hence, top carbon needs two more valence electrons to complete its octet.

So convert one lone pair from each left carbon atom and top right carbon atom to make a new bond with the adjacent carbon atoms. And then, the Lewis structure of C6H6 looks something like this:

Lone pair of left carbons and top right carbon is converted, and octet is completed on atoms | Image: Root Memory

In the above structure, you can see that the octet is completed on the central atom (top 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.

#5 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 each carbon atom

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

Formal charge = 4 – 0 – ½ (8) = 0

  • For each hydrogen atom

Valence electrons = 1
Nonbonding electrons = 0
Bonding electrons = 2

Formal charge = 1 – 0 – ½ (2) = 0

Mention the formal charges of atoms on the structure. So the Lewis structure of C6H6 looks something like this:

Formal charges are calculated, and got the stable Lewis structure of C6H6 | Image: Root Memory

In the above structure, you can see that the formal charges of both (carbon and hydrogen) are zero. Therefore, this is the stable Lewis structure of C6H6.

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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