Is a conductor like a capacitor
I'm not a quantum mechanics expert, but short answer is YES!
According to the quantum tunneling theorem found in here. Electrons can pass through dielectric and end up on the other side of the capacitor.
In fact, there is a chance -however small- that an electron can exist somewhere in between the protons themselves.

http://en.wikipedia.org/wiki/Quantum_tunnelling

http://www.youtube.com/watch?v=EuU9Yin_2mM