1. Dec 27, 2011

### elegysix

Suppose we could isolate a single proton and a single electron, and have them near each other without the high kinetic energies like in particle colliders.
imagine holding them in a perfect vacuum without gravity, a mm or so apart lol. Then we let them go.

What would they do? They're attracted because of opposite charges, but would they form hydrogen without any initial kinetic energy?

2. Dec 27, 2011

### mathman

They would attract and form a hydrogen atom. No initial K.E. is needed.

3. Dec 27, 2011

### Drakkith

Staff Emeritus
Indeed they would form a hydrogen atom and would release energy upon electron capture.

4. Dec 28, 2011

### elegysix

ok... So here's another one:

I know that emissions are quantized, but theoretically I can put the electron at any initial position/velocity.

So what happens if I give the electron just a little more initial energy than before, such that it is less than the minimum needed for an additional/increased emission?
Where/what does the 'increased remainder' go/do?

5. Dec 28, 2011

### Drakkith

Staff Emeritus
The extra is released, either in the form of radiation or kinetic energy. Falling to one of the available states from being unbound is not quantized as far as I know, only the movement between 2 different states is.

6. Dec 29, 2011

### Staff: Mentor

It's always quantized, and this falling from a great distance is still a transition from one state to another. It's just that in the "unbound" (precisely, so far away that the binding energy is negligible) states the gap between adjacent energy levels is so small, and each energy level is so close to zero (the limit at infinite distance) that you can ignore the quantization.

7. Dec 29, 2011

### Antiphon

I'm not sure, someone please confirm- if the incoming electron has a kinetic energy which is between two atomic levels, the excess will be transferred to the atom itself which is not bound and can move freely.