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Hi, this is Dr. B. Let's do the SO2 Lewis structure. On the periodic table: Sulfur,
6 valence electrons. Oxygen has 6. We have two Oxygens, though, for a total of 18 valence
electrons. We'll put the Sulfur in the middle; it's the least electronegative. Oxygens on
the outside, and then we'll use our valence electrons. Two between atoms to form chemical
bonds, and then let's go around the Oxygens here. Two, 4, 6, 8, 10, 12, 14, 16, we'll
put two here, 18, and we've used all our valence electrons. You can see the Oxygens both have
an octet; eight valence electrons. The Sulfur, however, only has 6. So we can move two valence
electrons from here and share them with the Sulfur. Now Sulfur has 8, and the Oxygens
both have 8 as well. You might think we're done at this point; however, Sulfur can hold
more than 8. It's in period 3 of the periodic table, the third row, so we'll want to check
our formal charges on this. For Oxygen, on the periodic table, it's in group 6, it has
6 valence electrons. Nonbonding, we have these right here, 6. And then bonding, there are
two, which we'll divide by 2. Six minus 6 minus 1 gives you negative 1. For the Sulfur,
we have 6, because it's in group 6 on the periodic table. Two nonbonding, and then 2,
4, 6 bonding divided by 2. Six minus 2 minus 3 gives us a positive 1. For the last Oxygen,
6 valence electrons, 2, 4 which are nonbonding, and then 4 right here which are bonding, divided
by two. Six minus 4 minus 2 is zero. So looking at our formal charges here, we have nonzero
formal charges. This may not be the best structure. So we're going to want to try to change something
to see if we can get these to zero. When I see this +1 here, it makes me think that I
should move 2 electrons to the center here. So let's get rid of these and put them right
here. Sulfur has more than 10 now, but I think that's going to solve our problem. Let's check
and see. So for the Oxygen, still 6; now we have 4 nonbonding and 4 bonding, we'll divide
by 2. Six minus 4 minus 2: zero. For the Sulfur, 6 minus 2 nonbonding; and now we have a total
of 8 bonding, divided by 2. Six minus 2 minus 4 is zero. And then this last Oxygen over
here, 6 minus 4 nonbonding; 4 bonding divided by 2: that gives us zero, as well. So these
are all zero now, which is a much more reasonable structure for us to have for SO2. So this
would be the best structure for SO2, sulfur dioxide. This is Dr. B., and thanks for watching.