Why do atoms repel each other when their electrons aren't in any defined region of space? If we think of the electron as completely smeared out over the whole volume of the orbital, is the electric field just distributed evenly and continuously across it? Or do electrons always have a definite region in space and a definite momentum its just that we cannot measure them to exact precision? Thanks
They have electric fields and mutual electric repulsion (or attraction) persists as a result. It's as simple as that. If you try to interpret QM like that you will inevitably run into quite a few serious problems. The mainstream view is that quantum fluctuations of observables are intrinsic and not due to our own ignorance. Systems simply do not "possess" position or momentum in general.
But where do we measure the source of the electric field. In hydrogen, the electron could be different distances from the second atom about to collide. If the radius is 10^-10 meters, then the field could be much weaker if it was on the opposite side of its nucleus with respect to the incoming atom, right? (inverse square law)
I think I understand. I just read ZapperZ's article on the HUP misinterpretation. What I got from it is essentially this: Quantum mechanics is a theory that tells us how accurately we can predict the state of a quantum system, but we can always MEASURE a system to an arbitrary accuracy based on how good our device is. So the electron is always somewhere in the cloud, we just don't know where until we measure? Zz's article: http://physicsandphysicists.blogspot.com/2006/11/misconception-of-heisenberg-uncertainty.html