Why electrons does not fall into nucleus
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The electrons do not fall into the nucleus because they have too much energy, and are constantly moving around.
We tend to picture an atom like a tiny solar system, with electrons zipping around the nucleus like planets orbiting the sun – thanks Neils Bohr – but thanks to quantum mechanics we now know that model is wrong, and way too simple. It’s more accurate to say that electrons are moving around and that we can identify where they’ll *likely* be found, but we can’t know where they specifically are at any given moment.
Firstly, it’s because electrons are moving quickly and constantly. Because the electrons are moving quickly, they are supposed to lose energy and “fall” into the nucleus. This is where the second reason comes in. Each electron only moves within a certain place away from the nucleus. At this place, an electron’s energy level remains “fixed” even if it is quickly moving. At the small scale of the electron, such an environment exists. By moving only within those specific “places,” the electrons remain located away from the nucleus.
EDIT: My original attempt to explain made use of the concept of orbitals. I reviewed the feedback and re-compared their descriptions with those found online and revised my explanation accordingly.
/***Tried ELI5 by using mostly words that are part of the 1,000 most commonly-used words. I hope this helps***/
Actually sometimes an electron CAN be captured by the nucleus. It’s one type of radioactive decay:
https://en.wikipedia.org/wiki/Electron_capture
They can and do “fall” into the nucleus, but fall isn’t the right word, and I’ll explain why:
Electrons aren’t little balls that orbit the nucleus of an atom like planets. Despite the fact that it’s commonly depicted that way and even taught in schools, it’s completely incorrect. When we talk about subatomic particles, pretty much everything we think we know about how things behave on the macro scale goes out the window. Electrons aren’t physical objects with volume and shape and size, they’re what we call wavefunctions, which is essentially a smeared out area of probability of where the electron *could* be. So toss out the idea of nice neat little orbits and picture a fuzzy cloud instead. Electrons, depending on their energy levels, have their fuzzy clouds in different places. Electrons can lose energy (or gain it) but only if they do so through some specific interaction, and if they’re in their lowest energy state, they can’t go any lower. Now that we know electrons aren’t really physical objects in the way that we normally think of, it should maybe make it easier to understand that the idea of “crashing” or “falling” into the nucleus doesn’t really make sense. Electrons are fuzzy waves of probability and they can only exist in specific areas depending on their energy levels.
But there’s a catch! It turns out that electrons can localize inside the nucleus of an atom. It’s called electron capture and it’s how a certain type of radioactive decay works. Because electrons exist in this fuzzy wave-like area of probability, as long as this area overlaps with the nucleus which it does for the lowest energy level, closest to the nucleus), there’s always some probability that an electron can be inside the nucleus. If this happens and it interacts with a proton, the electron will localize inside the nucleus and interact with the proton to form a neutron.
A weird thing about quantum physics is that the more energy a thing has the smaller it becomes (the wavelength gets smaller).
An electron is thousands of time less massive than a proton and as such has less energy and larger wavelength. Which means it just doesn’t “fit” into the nucleus even though it does actually go there.
You can add a lot of energy to an electron and try to make it smaller. Unfortunately, energy required for an electron to leave the atom is lower than that, so that just won’t work.
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