Drawing the Lewis Structure for C2H2Br2
Transcript: This is the C2H2Br2 Lewis structure. We have 4 times 2; plus 1 for the Hydrogen, times 2; plus 7 times 2 for the Bromine, for a total of 24 valence electrons for the C2H2Br2 Lewis structure. Carbon's the least electronegative so we'll put the Carbons right in the center.
The question is, how do we distribute the Hydrogens and the Bromines? We could do it this way, where we have the Hydrogens on this side and the Bromines over here, or we could mix it up with a Hydrogen here and a Bromine here, and a Hydrogen here and a Bromine here. They are different chemical compounds, but we can't really tell from this structure up here which one we should draw. So let's go with this right here for now.
We have 24 valence electrons. We'll put 2 between atoms to form chemical bonds. We've used 10. And then complete the octets on the Bromine--12, 22. Now back to the central Carbons, 24. And we've used all 24 valence electrons. Hydrogens have 2 valence electrons, so their outer shells are full. And everything else has 8 valence electrons except this central Carbon here--it only has 6. So we're going to have to share electrons to form a double bond so we can fulfill the octets. Let's take these two valence electrons here, and move them to the center--share them.
We're still only using 24 valence electrons, but this Carbon has 8 valence electrons, and now this Carbon here has 8. Its outer shell is full, as well. So we've filled the outer shells in all the atoms in the C2H2Br2 Lewis structure, and we've used 24 valence electrons. For this C2H2Br2 Lewis structure, we really should call it 1,2-Dibromoethene. The "-ene" means we have the double bond here between the Carbons, and the Bromines are on the first and second Carbon in this structure. If both Bromines were on the first Carbon here, we would call it 1,1-Dibromoethene.
So that's the Lewis structure for C2H2Br2. This is Dr. B., and thanks for watching.