Hi, this is Dr. B.
We're going to do the Lewis structure for
NF3, nitrogen trifluoride.
On the periodic table, Nitrogen is in group
5 or 15, so it has 5 valence electrons; and
then Fluorine is in group 7 or 17, it has
7.
We've got three Fluorines, though, so let's
multiply that by 3.
That equals, 21 plus 5, is 26 valence electrons.
Nitrogen is the least electronegative, so
that's going to go in the center here, and
then we'll put the F's, those Fluorines around
there, and we have three of them.
OK, so at this point we've got 26 valence
electrons to work with.
Let's first put them between atoms to form
that chemical bond there.
So 2, 4, 6; and spread them around the outside
now.
So we have 2, 4, 6, 8, 10, 12, 14, 16, 18,
20, 22, 24, and we'll put the last two here,
26, which is what we had to work with, to
give Nitrogen an octet.
Let's check and see if everything has 8 valence
electrons, or an octet.
Fluorine has 8, this Fluorine has 8, and then
this Fluorine right down here, as well, has
8.
Their outer shells are full.
And then Nitrogen, well, it has eight, too.
So that's the correct valence electron count
for each of these, so our Lewis structure
is done.
And we could also draw it as a structural
formula, and that would look like this right
here.
That is the Lewis structure for NF3.
This is Dr. B., and thanks for watching.
