Physics 2000 Science Trek Quantum Atom

Schrödinger's Atom

So what's wrong with the idea of electrons going around in orbits?

A physicist named Erwin Schrödinger showed that electrons are really waves that...

Hold it! What do you mean electrons are waves?! I thought they were particles!

This is where quantum physics gets truly bizarre. If you perform an experiment to see where a particle is, then you find something particle-like. But otherwise it's a wave that carries information about where the electron probably is. The famous Two-Slit Experiment is another way of looking at the dual wave/particle nature of electrons.

What do you mean when you say the electron "probably is" somewhere? Isn't the electron in some definite place?

Well, no. Until you check where it is, it's really just a wave. Not only that, but Schrödinger showed that these electrons don't even move. The waves are stationary. Each time you check where an electron is you will find it in a different place, but that doesn't mean it's moving in between checks. For some energy levels, if you check position enough times you may see an "orbit-like" pattern, but don't be fooled into thinking that electrons are actually moving around in little circles.

So where is an electron when you're not looking? Doesn't it have to be somewhere?

That's the bizarre part: an electron isn't in any particular place when you aren't looking. Fortunately, for most physics it doesn't really matter where it actually is, we only care about how much energy it has.

Oh! And that's why orbits are useful! They may be misleading about where the electron is, but they do tell us how much energy it has.

We call this the Energy Level of the electron. Because the idea of orbits is so misleading, physicists started using a picture of the atom which just showed energy levels as relative heights.

And we call this the "Schrödinger Model," of course. So in this applet, the picture to the left of the Bohr Model shows the energy level of the electron, and the picture to the right shows the areas around the nucleus where the electron will probably be found.

You can interact with the Bohr hydrogen atom in this applet just like the last one, except now you will see the changes in the Schrödinger model as well.

Click on an orbit to change energy levels.
The electron will eventually decay down to its ground state on its own.