Hi, this is Dr. B. Let's do the Lewis structure
for CCl4, Carbon Tetrachloride, sometimes
just called Carbon Tet.
We'll start by looking at the valence electrons.
Carbon is in group 4 or 14, so it has 4.
Chlorine has 7 valence electrons, but we have
4 Chlorines so let's multiply that by 4.
Four plus 28 equals 32 total valence electrons
to work with.
Carbon is the least electronegative, we'll
put that at the center, and then we'll put
the four Chlorines around it like this.
OK, so now we've got 32 valence electrons
to work with.
We'll form chemical bonds first between the
Carbon and the Chlorines.
So we've done that, we've used 8 valence electrons.
Now let's fulfill the octets on the Chlorines,
so we have 8, 10, 12, 14, 16, 18, 20, 22,
24, 26, 28, 30, and then 32.
We've used all 32 valence electrons.
Now we want to see if we have octets.
All of the Chlorines have 8 valence electrons
around them.
That means that their outer shells are full
and that they have octets.
In the center, the Carbon has 8 valence electrons
so its octet is full as well.
So we've actually satisfied the octets.
We've used all 32 of the valence electrons
available.
We could write it as well as a structural
formula that would look like this right here.
That's it--that's the Lewis structure for
CCl4, Carbon Tetrachloride.
This is Dr. B., and thanks for watching.
