Promotion Energy of Nitrogen, Oxygen, and Fluorine

[Sean Sugai 4E]

Why can't nitrogen, oxygen, and fluorine use promotion energy to increase the number of bonds it can form? I know it has to do with no empty p-orbitals, but what does that specifically mean?

[Mariepahos4D]

I am not sure if this is exactly what you are asking, but N, O, and F cannot have more than an octet because they're energy level does not have a d orbital that it can use.