why aren’t electrons pulled into the nucleus? They’re negatively charged and the nucleus is positively charged, so I don’t understand what’s stopping them.
In: Chemistry
Electrons don’t orbit the nucleus. That’s a cartoon model, and you’re right that if they were actually orbiting, they would have to be pulled in. The truth is that the electron has a chance to be *anywhere*. Yup, even inside the nucleus. But that chance is really, really, really small. It’s much more likely to find the electron at specific distances away from the nucleus. These are the orbital distances you learned about.
How does this work? Well, matter on the atomic scale abides by interesting rules, like the Heisenberg Principle, one of the weird rules that pops up in quantum mechanics which says that you can’t both know where a particle is located and how quickly it’s moving. The better you know where a particle is located, the more uncertain its velocity becomes.
Because of Heisenberg, if the electron was in the nucleus, it’d be in such a crazy small location that its speed would be very uncertain! It’d be very likely to have a high speed, so the chance it’d leave the nucleus would be really, really huge.
The electron finds a good compromise between its position and velocity at the orbital distance, where you can most often find it hanging out.
The [Heisenberg Uncertainty Principle](https://en.wikipedia.org/wiki/Uncertainty_principle).
A particle can’t have a well-defined momentum and position at the same time.* If an electron is in the nucleus, the uncertainty in it’s position must be very small, but that means the uncertainty in it’s momentum is correspondingly large. But with an uncertain momentum, it won’t stay in that small certain position for long.
You may wonder why protons and neutrons can stay in the nucleus, since they are also affected by the Uncertainty Principle. The reason is that they are much more massive than electrons, which means for a given amount of momentum, they have much less velocity.
*Sometimes, this is confused with the [observer effect](https://en.wikipedia.org/wiki/Observer_effect_(physics)), where a particle’s momentum/position are altered by observing it. That is a real thing, but separate from the Uncertainty Principle. The Uncertainty Principle is a fundamental law of the universe that applies even when no one is looking. [Here’s a good video](https://www.youtube.com/watch?v=MBnnXbOM5S4) that explains why it works the way it does.
As an analogy: It is as if you had an intangible baseball that had mass and it started a million miles from Earth. It is attracted to Earth, but when it contacts the surface, it is not slowed because it is intangible. It keeps going and reaches the center but now has its maximum velocity and continues, now slowing until it reaches a million miles out the other side before again plunging earthward, oscillating forever. Now… It is inside Earth sometimes, but terribly briefly, so perhaps the best way to describe its location over time is to say that it occupies an “intangible baseball orbital” around the Earth.
Well in the general macro world, you are right. Opposite charges attract each other. Two magnets of opposite poles crash into each other. In the quantum world, it is very different.
It’s almost like how the moon orbits earth. It wont crash into earth because it’s at a stable orbit. The electrons are in a stable “orbit” with just the right amount of energy to to stay or exit to a new orbital. The energy between the nucleus and electron balances out where they dont crash into each other. But in theory, removing that energy balance would indeed cause them to crash into each other.
The real answer is we don’t know. We have models for how subatomic particles work and theories but we don’t really know.
Pre-relativism electrons were thought to be small objects that orbited a nucleus like a planet orbiting the sun. But now scientists do not believe that.
A neutron is basically a proton plus an electron plus something. A proton plus an electron has no net charge but not enough mass to be a neutron.
So an electron falling into a proton is not stable. It is missing something that stabilizes it as a neutron and the electron will move away again instead of merging.
We just cannot explain what something as small as an electron is. A proton is 1836 times more massive.
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