Boron's empty p orbital in BF3

[SaintJude]

So BF3 is trigonal planar, but then how does Boron in BF3 also have an empty p-orbital?
Should the diagram below help me understand how B in BF3 has an empty p orbital?

I ask b/c understanding that B has an empty p-orbital was crucial to me identifying it as a lewis acid.

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[Buttafuoco]

Always remember that orbitals in = orbitals out. 2 Ps and 1 S make 3 SP2s so you must have a P left over.

 

[gettheleadout]

The p orbital just isn't shown in that diagram because it's neither occupied nor a hybrid orbital.

 

[hellocubed]

Yeah, notice they meshed 4 boxes, and there's only 3 there.

One is left out.