In a material with mobile particles, why do they move so freely in response to an electric field?

Question

In a metal or semiconductor, there are electrons in the conduction band which are free to move. But looking at it from a charge perspective, when you introduce an electron in a quasi-neutral semiconductor, wouldn't the electrons already in the region be pretty "close" to their positively charged nucleus'. So even when an electron in an atom feels an opposing force by the additional electron, won't the positive charge from the nucleus hold it back, since of course a proton and the additional electron both have equal amount of charge, and the atom electron is pretty "close" to the nucleus. so why do we assume the atom's electron will so freely move in direction of E-field or that an additional electron will repel an atom's electron away from nucleus, since of course the additional electron and the proton in nucleus have equal amount of charge. Because it seems that we just assume electrons automatically move away from their atom easily in conduction when shouldn't they be held back with the positively charged nucleus.

Answer 1

I think you need to consider the energy level of the orbital shell that the electron is in.  As you move out from the nucleus, the +/- attraction becomes weaker.  If I recall correctly, the attraction is inversely proportional to distance squared.

The amount of potential required to dislodge an electron from the outer shell IS an indication of the resistance of the material.  Thus a perfect conductor would require zero potential for electron flow and a perfect insulator would have zero electron flow regardless of potential.

It may help if you try to think of the situation from the perspective of Quantum Physics rather than Classical Physics.  The laws are a lot different.