: : : : The reality of nature is scale dependent. This is what caused quantum mechanics to be an incomplete theory prior to renormalization. What exists at certain scales has no physical reality at all at other scales. Quantum foam (even if it does exist) may describe reality at sub planck length scales but it would have no reality whatsoever at larger scales.

: : Hey, guys, you both forgot that there is electric field there (bunch of virtual photons) on the macroscopic scale. On the Plank scale there is not much difference between electron and vacuum - both consists of fluctuating space itself.

: Don;t forget the uncertainty principle. You don;t really know exactly where the electron is. Trying to pinpoint its location would alter its location. So in all practicality, there really isnt any measureable amount of "empty space" in an atom.