C6H6 (benzene) has six carbon atoms and six hydrogen atoms.
In the C6H6 Lewis structure, there are three single bonds and three double bonds between the six carbon atoms, and each carbon is attached with one hydrogen atom. And none of the atoms has a lone pair.
Steps
To properly draw the C6H6 Lewis structure, follow these steps:
#1 Draw a rough sketch of the structure
#2 Next, indicate lone pairs on the atoms
#3 Indicate formal charges on the atoms, if necessary
#4 Minimize formal charges by converting lone pairs of the atoms
#5 Repeat step 4 if necessary, until all charges are minimized
Let’s break down each step in more detail.
#1 Draw a rough sketch of the structure
- First, determine the total number of valence electrons
In the periodic table, carbon lies in group 14, and hydrogen lies in group 1.
Hence, carbon has four valence electrons and hydrogen has one valence electron.
Since C6H6 has six carbon atoms and six hydrogen atoms, so…
Valence electrons of six carbon atoms = 4 × 6 = 24
Valence electrons of six hydrogen atoms = 1 × 6 = 6
And the total valence electrons = 24 + 6 = 30
Learn how to find: Carbon valence electrons and Hydrogen valence electrons
- Second, find the total electron pairs
We have a total of 30 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 = 30 ÷ 2 = 15
- Third, determine the central atom
Here hydrogen can not be 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.
Now there are six atoms remaining and all six atoms are carbon, so we can assume any one as the central atom.
Let’s assume that the central atom is top carbon.
Therefore, place carbons in the center and hydrogens on either side.
- And finally, draw the rough sketch
#2 Next, indicate lone pairs on the atoms
Here, we have a total of 15 electron pairs. And twelve bonds are already marked. So we have to only mark the remaining three 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 hydrogen is a period 1 element, so it can not keep more than 2 electrons in its last shell.
Always start to mark the lone pairs from outside atoms. Here, the outside atoms are hydrogens, left carbons, right carbons, and bottom carbon. But no need to mark on hydrogen, because each hydrogen has already two electrons.
So for each left carbon, there is one lone pair, and for one right carbon, there is one lone pair, and for remaining carbons, there is zero lone pair because all three electron pairs are over.
Mark the lone pairs on the sketch as follows:
#3 Indicate formal charges on the atoms, if necessary
Use the following formula to calculate the formal charges on atoms:
Formal charge = valence electrons – nonbonding electrons – ½ bonding electrons
For top carbon, bottom carbon, and bottom right carbon atom, formal charge = 4 – 0 – ½ (6) = +1
For each left carbon and top right carbon atom, formal charge = 4 – 2 – ½ (6) = -1
For each hydrogen atom, formal charge = 1 – 0 – ½ (2) = 0
Here, the carbon atoms have charges, so mark them on the sketch as follows:
The above structure is not a stable Lewis structure because the 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 top left carbon atom to make a new C — C bond with the top carbon atom as follows:
#5 Repeat step 4 (minimize charges again)
Since there are charges on the carbon atoms, again convert a lone pair of the top right carbon atom to make a new C — C bond with the bottom right carbon atom as follows:
#6 Minimize charges again
There are still charges on the carbon atoms, so again convert a lone pair of the bottom left carbon atom to make a new C — C bond with the bottom carbon atom as follows:
In the above structure, you can see that the central atom (top carbon) forms an octet. The outside atoms (remaining carbons) also form an octet, and all hydrogens form a duet. Hence, the octet rule and duet rule are satisfied.
Also, the above structure is more stable than the previous structures. Therefore, this structure is the stable Lewis structure of C6H6.
Next: NBr3 Lewis structure
External links
- https://www.thegeoexchange.org/chemistry/bonding/Lewis-Structures/C6H6-lewis-structure.html
- https://sciencestruck.com/c6h6-benzene-lewis-dot-structure-polarity
- https://techiescientist.com/benzene-lewis-structure/
Deep
Learnool.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.