Chemical Bonding: C₆H₆ Lewis Structure

Drawing the Lewis Structures for C₆H₆ (including Benzene)

Viewing Notes:

• With C₆H₆ there are sevearl possible Lewis structures that can be drawn. They are "correct" in that they fill the outer shells of each atom in the structure and use the exact number of valence electrons available for the C6H6 Lewis structure.
• C₆H₆ has a total of 18 valence electrons.
• The most common Lewis structure for C₆H₆ is Benzene. Benzene has a ring structure with alternating double bonds.
• You'll see a Benzene ring as part of many organic chemical compounds. Compounds with the Benzene ring are called "aromatic" coumpounds.
• Remember that Hydrogen (H) atoms always go on the outside of a Lewis structure.
• Note that Hydrogen only needs two valence electrons to have a full outer shell.

Transcript: For the C6H6 Lewis structure there are three ways we can draw it. The most common is Benzene. I'll explain how to do that and then show the other two ways that we can draw the C6H6 Lewis structure.

So we have a total of 30 valence electrons to work with. For Benzene we're going to put the carbons in a ring structure. Then we'll put the hydrogens outside of the carbons. We have our skeleton structure, so let's put two electrons between each of the atoms to form chemical bonds. So we'll put them like this and the go around and do that for all of the atoms.

So we have six valence electrons so we'll put, I don't know, two here, two here and then two here. But you can see right away we have octets on these carbon atoms, but these other three only have three bonds, so they only have six valence electrons and they don't have a full outer shell. So we're going to need to form some double bonds. It looks like we'll need three double bonds. So let's take these two valence electrons and form a double bond between these two carbons. So now these two carbons here, they have eight valence electrons in their outer shell.

We can form another double bond but we can't put it right next to the one we just formed because then that carbon right here would have more than eight valence electrons. So we'll need to alternate our double bonds. Let's take these two right here and form a double bond here. And finally let's take these two and form a double bond right here.

So now we're still using 30 valence electrons but each of the carbons has eight valence electrons so its octet is satisfied. So this is a viable Lewis structure for C6H6, in fact it's called Benzene and it's quite common in organic chemistry. Because Benzene is commonly used in organic chemistry there are a number of other ways we can draw it. These structures are intended to make it easier to draw the Benzene Lewis structure. You could also draw the C6H6 Lewis structure like this ... or ... like this. There are probably even some other ways that I haven't thought of.

So that's the Lewis structure for C6H6, probably the most common would be the Benzene, that's probably what you would be expected to know. But there are other isomers, or ways to draw the C6H6 Lewis structure.

This is Dr. B., and thanks for watching.