Drawing the Lewis Structure for C2F4

Viewing Notes:

  • With C2F4 you are going to run out of valence electrons and will have to share more than one pair of electrons between the Carbon atoms.
  • Remember that Hydrogen (H) atoms always go on the outside of a Lewis Structure.
  • Note that Hydrogen only needs two valence electrons to have a full outer shell.

Transcript: 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.