[jinelcrimp8 (OP)]

Why don't electrons crash into the nucleus? My entire academic career this question has been glossed over. I mean, electrons are negatively charged, protons are positively charged, we all know the implications. I remember when I first learn about the Gold Foil experiment, they brought up my above point as a potential hole in the experiment's logic, then never revisited the idea. I also ask a teacher this once, but he said it was a complicated solution (which I perfectly understand) and that he didn't think he could explain it adequately.

[Bored chemist]

The uncertainty principle.
If they did, we would know their position (at the nucleus) and their momentum (nil, because they wouldn't be moving) at the same time.
That's not allowed.

[chiralSPO]

It is entirely reasonable to say that an electron in an atomic orbital *has* fallen all the way to the central nucleus. It just so happens that electrons are effectively fluffy, and spread out over a volume 100,000 times larger that that occupied by the nucleus. Similar to how the atmosphere on Earth has fallen all the way down to the ground, but still measurably extends more than 100 km from the surface.

[alancalverd]

I've never liked the term "uncertainty principle", which implies a problem of measurement or perception. It's actually an indeterminacy principle, though the numbers are the same.

If an electron really was whizzing around, it would be changing direction all the time and thus radiating photons, which it  doesn't, and eventually losing all its kinetic energy and crashing into the nucleus, which it doesn't. What Heisenberg said was that as an electron has mass, it can have momentum, but there is an irreducible indeterminacy of position and momentum such that we can only define the probability of finding a particle at a particular position in an infinitesimal amount of time.

It's sort of obvious if you want to define the speed and position of a car: if you know exactly where it was at one point in time, you don't know whether it was moving because movement is change of position divided by change of time, and 0/0 is not defined.

[Bored chemist]

It's sort of obvious if you want to define the speed and position of a car:

It is parked in the garage.
And it is by no means obvious that I can't say that it is exactly in the middle of the garage and it is (of course) stationary.
The things about Heisenberg's principle is that it is "obviously" wrong.
Of course, it's actually right.

[alancalverd]

You can also define the speed and position of an isolated electron, come to think of it.