Drawing the Lewis Structure for PF3

Viewing Notes:

  • PF3 is similar to PBr3 and PCl3. If you can do those Lewis structures PF3 will be easy.
  • In the PF3 Lewis structure Phosphorus (P) is the least electronegative so it goes in the center.
  • In the Lewis structure for PF3 there are a total of 26 valence electrons. Three pairs will be used in the chemical bonds between the P and F.

Transcript: This is Dr. B. Let's do the PF3 Lewis structure. On the periodic table: Phosphorus, 5 valence electrons; plus Fluorine, we have 7, but we have three Fluorines so we...5 plus 21: 26 total valence electrons. We'll put the P at the center, and we've got three F's. Let's put them like this. We'll start by putting electrons between each atom, two of them, to form a chemical bond. And then around the outside atoms. So we've used 2, 4, 6, so we have a total of 20 to use up the 26. So 2, 4, 6, 8, 10, 12, 24, and we have two left, and we'll put those on the central atom. At this point, everything has eight valence electrons.

So we've used 26 valence electrons that we started with. Everything has an octet. If we wanted, we could check the formal charges and you'd see that those work out. So this is the best structure for PF3. This is Dr. B., and thanks for watching.