Chemical Bonding: C₂H₂Cl₂ Lewis Structure

Drawing the Lewis Structure for C₂H₂Cl₂

Viewing Notes:

• With C₂H₂Cl₂ there are only single bonds.
• Carbon is the least electonegative atom so it goes at the center of the C₂H₂Cl₂ Lewis structure.
• 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.
• In the Lewis structure for C₂H₂Cl₂ there are a total of 20 valence electrons.

Transcript: This is the C2H2Cl2 Lewis structure. Carbon has 4 valence electrons, two Carbons; Hydrogen has 1 valence electron, but we have two Hydrogens; plus Chlorine, which is 7, and we have two Chlorines, for a total of 24 valence electrons. Carbon's the least electronegative, and we'll put that in the center, and we know Hydrogens always go on the outside.

But here's the problem: where do we put the Hydrogens? Do we do it like this, where we put two Hydrogens on on side and two Chlorines on the other? Or do we do it like this, where we have a Hydrogen and Chlorine on one side, and then on the other we have a Hydrogen and Chlorine. They're very different chemical compounds. They have different properties. So we can't really tell, looking at this structure up here, which way we're supposed to do it.

So let's go with this right now. We have 24 valence electrons for the C2H2Cl2 Lewis structure. We'll put two electrons between atoms to form the chemical bonds, like this, so I've used 10. Then around the Chlorines, 12, 22, and then back to the central Carbons, 24. But we've used all 24 valence electrons. We can see that both Hydrogens have 2 valence electrons, and that's all they need for a full outer shell. This Carbon here has 8, the Chlorine, and this Chlorine has 8 as well. Their octets are completed.

However, this Carbon right here only has 6. So we're gonna have to share electrons to form a double bond in order to get it to 8 valence electrons. Let's move these 2 valence electrons right here into the center to form a double bond. We're still using 24 valence electrons, but now this Carbon here has 8 valence electrons, as does this. So the octets are complete on all the atoms in the C2H2Cl2 Lewis structure.

For this structure, because we have the Chlorines on the first and second Carbons, we're going to call it 1, 2-Dichloroethene. If both Chlorines were on the first Carbon, it would be 1, 1-Dichloroethene.

That's the Lewis structure for C2H2Cl2. This is Dr. B., and thanks for watching.