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.