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.
