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Hi, this is Dr. B. Let's do the Lewis structure for PF5. On the periodic table, Phosphorus
is in group 5, it has 5 valence electrons. Fluorine, group 7, but we have five of those,
so we need to multiply that 7 by 5. Five plus 35: 40 valence electrons. We'll put the Phosphorus
in the center, and then the Fluorines, we have five of them, let's put them around it
like this. We'll connect the Phosphorus to each Fluorine with a single line representing
a pair of electrons, like that. So we've used 2, 4, 6, 8, 10 valence electrons. That means
we have 30 left. And then we'll fill the octets for the outer atoms. We have 30 valence electrons.
Two, 4, and 40. At this point, all the Fluorines have 8 valence electrons, so their outer shells
are full. The Phosphorus in the center has 10 valence electrons, but that's OK. Phosphorus
is in period 3 of the periodic table, and those elements and the ones below can hold
more than eight valence electrons. If you wanted to make sure you had the right structure,
you could check the formal charges and you'd see that they're all zero. So this is the
correct structure for PF5. This is Dr. B., and thanks for watching.