This is the PF6- Lewis structure.
Phosphorus has 5 valence electrons; Fluorine
has 7.
We have 6 Fluorines, and we need to add in
this valence electron up here for a total
of 48 valence electrons.
Phosphorus is the least electronegative.
We'll put that at the center and then we'll
put the 6 Fluorines around the outside.
We'll form chemical bonds between the Fluorine
and the Phosphorus.
Each of these is 2 valence electrons.
So we have six bonds.
We've used 12 valence electrons.
Completing the octets of the Fluorines, we
have 12, 14, 16, and 48.
So we've used all 48 valence electrons in
the PF6- Lewis structure.
The key here is that Phosphorus is below Period
2 in the periodic table.
That means it can have an expanded octet.
It can hold more than 8 valence electrons.
Here, it's holding 2, 4, 6, 8, 10, 12.
That's OK, though.
Because of that expanded octet, we can do
that.
If you were to look at the formal charges,
you would find that Phosphorus has a formal
charge of -1.
That makes sense, because this is negative
up here.
So that's the Lewis structure for PF6-.
This is Dr. B., and thanks for watching.
