I’m guessing “sticking right to each other” doesn’t make much sense on the subatomic level but hoping someone can make things clearer.
In: Physics
Electrons are constrained by their wave function. Unlike the billiard ball examples from science class, electrons are not a “tiny little thing”. They are a particle where their quantum nature is more readily apparent than in macro particles, which can “touch” each other when the electrons on their outer surface can effectively repel each other.
Electrons *don’t* spin around the center.
In fact, for the first electron in an atom, the most likely place for it to be is in fact inside the nucleus, and that electron has no average orbital angular momentum at all!
The answer to your question comes from the fact that, at that scale, particles don’t have definite positions. They’re “smeared out”, and the lower their energy is, the more smeared out they are.
Making the electron “stay” inside the nucleus (that is, smushing all of it into that volume) requires confining it to a very small area, which takes much more energy than that electron actually has. Imagine a very hyperactive hamster: to keep it in one place you’re gonna need strong walls around it, otherwise it’s gonna run all over the place. Protons and neutrons, which are much larger than electrons (and therefore have much higher energies, because mass and energy are equivalent) smear out much less, but in fact they obey the same sort of behavior – there are ‘orbitals’ of sorts within the nucleus as well.
It’s slightly more complicated than this but it’s due to quantum mechanics. Specifically, it’s due to limitations on the allowed energy levels of electrons. Electrons in an atom actually exist as probabilistic clouds where at any point there is a non-zero probability of finding the electron when you measure it. The shapes of these clouds – the wavefunctions of the electrons – are described by the Schrodinger Equation, and different energy levels have different shapes. Additionally, energy is quantised; the minimum resolution of energy levels is the Planck energy.
For an electron to fall into the nucleus it would have to emit energy to go down one energy level. However, electrons cannot fall to lower energy levels than their ground state due to Heisenberg’s uncertainty principal and the quantisation of energy.
A common, though flawed, way of thinking about it is as a standing wave around the nucleus. A standing wave must have an integer number of periods, and the electron can only exist as valid forms of these standing waves. If the electron is in a state corresponding to the standing wave with the minimum number of periods, then it doesn’t make sense for it to move to a lower level.
First, electrons want to be close to the nucleus, for exactly the reason you stated: they attract each other. The closer they are the less energy they have, making the nearest orbital stable.
However, electrons are wave objects. They have a wavelength which is larger than the size of the nucleus. As such, the electron simply doesn’t fit in.
The bottom orbital is actually right on top of the nucleus. You could say that the electron is in the nucleus, only that its smeared location puts some of it outside of the nucleus.
To fit the electron in the nucleus you would have to decrease its wavelength. But that requires energy, lots and lots of energy. An electron doesn’t have it and no chemical reactions (between electrons) can provide enough. What’s worse, required energy is higher than the energy needed to kick the electron out of its orbital, which means that it will rather escape than stick.
Nuclear reactions do have enough energy though. In unstable isotopes it is actually possible for a proton to capture an electron. The two together become a neutron. The opposite is possible, too, in fact a neutron outside of an atomic nucleus decays into a proton and an electron in a few minutes on average.
Imagine a ball of cotton sugar as an electron. Imagine a small empty ball as a nucleus and they both attract. You can’t fit the cotton inside the ball until you squish it really hard, and that squishing requires lots and lots of energy. You have to beat it down with a bat. But, while you’re hammering at it, you’re more likely to shake off the candy entirely away from the ball rather than push it inside.
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