Hi, this is Dr. B. Let's do the Lewis structure
for CS2.
On the periodic table, Carbon's in group 4,
sometimes called 14, so it has 4 valence electrons.
Sulfur in group 6 or 16, it has 6.
We have two Sulfurs so let's multiply that
by 2.
Four plus 12: 16 valence electrons.
Let's draw it.
Carbon, the least electronegative, goes in
the center and then we'll put the Sulfurs
on either side here.
Now we want to add our valence electrons.
Remember, we've got 16 to work with.
We'll put 2 between the atoms and then we'll
put them on the outside.
So we have 2, 4, 6, 8, 10, 12, 14, 16.
We've used those 16 up.
Let's see if we have octets.
Eight on that Sulfur, eight on that Sulfur,
those have full outer shells; but in the middle,
Carbon only has 4.
So we've got to fix that.
We can take and move valence electrons between
atoms and share them so this Sulfur has 8
now, still, but the Carbon has 6.
We're almost there.
Let's share this side here to be symmetrical.
Now, again, we have 8 on that Sulfur, but
the Carbon now has an octet.
It's stable, and its octet is satisfied, and
we've used only the valence electrons that
we had available.
So we have this structure here, and we can
also write it as what is called a structural
formula.
That's going to look like this right here.
With the structural formula, a line represents
a pair of electrons.
So we have two pair of electrons here, and
we have these two lines here.
That's the Lewis structure for CS2.
This is Dr. B., and thank you for watching.
