Tip:
Highlight text to annotate it
X
This is the Lewis structure for C2F4. We'll look on the periodic table: Carbon has 4 valence
electrons, it's in group 4 or 14, but we have two Carbons. And then Fluorine in group 7
or 17 has 7 valence electrons, but we have 4 of those. So 8 plus 28 equals 36 total valence
electrons. Carbon is the least electronegative so those Carbons will be at the center and
then we'll put the Fluorines on the outside. We have a total of 36 valence electrons for
C2F4. We'll put a pair of electrons between each Carbon and Fluorine to form chemical
bonds; so we've used 2, 4, 6, 8. We'll put two in the center here, 10, and then go around
the outside, 12, 14, and 34. So we've used 34 valence electrons but we had 36 to start
out with, so we'll put these here, and we've used all 36. Let's see if we have octets for
each of the atoms. Fluorine needs 8 valence electrons, and each of the Fluorines has 8
valence electrons, so its outer shell is full. Carbon also needs 8. This Carbon here has
8, but this Carbon right here only has 6 valence electrons, so it does not have an octet. What
we can do is take two valence electrons from this Carbon right here and share them with
the other Carbon to form a double bond. So now this Carbon has 8, and this Carbon has
8. By sharing that pair of electrons, we've been able to complete the octets on the Carbons.
The Fluorines are good. So this is the Lewis structure for C2F4, and this is Dr. B.; thanks
for watching.