If the protons and neutrons had, say, a hundred times more mass than they normally do, could the atom overall still be stable? Would it affect the atom's electron cloud somehow, or would it still be able to retain its chemical properties?

Additionally; if the nucleons gained this extra mass by being Kaluza-Klein states of protons and neutrons (meaning their constituents would still be the same kind and configuration of quarks, but only differ in mass due to their momentum in extra-dimensions), and not via interaction with the Higgs field, would it alter the way more massive nucleons would affect an atom?

This is meant to be an element alongside our known physical laws, so I'm not wondering how the universe would look like if this were the case since the Big Bang.

In short; What would happen if protons and neutrons were a hundred times heavier, but everything else kept its normal mass?

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    $\begingroup$ Since you're not interested in how such a fictional universe would look or function, I think your query might fit better over on the Physics Stack. Here in Worldbuilding, we'd be much more interested in the ramifications of such a set-up. $\endgroup$ – elemtilas Jul 13 '19 at 11:09
  • $\begingroup$ Welcome to Worldbuilding, Yaro, your question is more hypothetical physics than anything else. I'd be asking myself would the strong nuclear force be able to hold one hundredfold more massive protons & neutrons together? My guess is no, but I'd love to be proven wrong.. $\endgroup$ – a4android Jul 13 '19 at 12:17
  • $\begingroup$ @a4android - Would the mass affect the equilibrium distance between charged particles if the gravitational force is negligible compared to other forces? I don't know how this stuff works in quantum field theory but if you think of a classical example like a charged ball that's pulled in one direction by an opposite charge, and pulled back in the other direction because it's attached to a spring fixed to a wall, if the gravitational force is negligible the ball's own mass wouldn't seem to make a difference in terms of how far the spring would be stretched at equilibrium. $\endgroup$ – Hypnosifl Jul 13 '19 at 14:27
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    $\begingroup$ I suspect this sort of "what if reality was different" question would be closed on Physics SE as being either a personal theory or non-mainstream (covered by same rule). $\endgroup$ – StephenG Jul 13 '19 at 15:05
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    $\begingroup$ This definitely should not be on Physics; it would be closed. I'd ask people not to vote to migrate it there. $\endgroup$ – HDE 226868 Jul 13 '19 at 16:29

On the chemical level, electron orbitals are determined by the electric potential of an atom's nucleus. The electric potential of an atom's nucleus comes from the atom's protons. Different isotopes of an element have virtually identical chemical properties because the electric potential of an atom comes from the number of protons. If increasing the mass of an atom's nucleons is just like adding more neutrons then increasing the mass of an atom's nucleons won't break chemistry. The Periodic Table of the Elements will be exactly the same except the decimal place on the atomic masses will have moved two digits to the right.

The above analysis assumes a proton's charge radius doesn't change. If you increase a proton's mass without increasing its charge radius then no harm is done. But protons are matter waves. Increasing the mass of a matter wave decreases its wavelength. It is therefore conceivable that increasing a proton's mass would decrease its charge radius. This does change chemistry slightly because changes to a proton's charge radius affect the proton's electric potential.

In particular, decreasing a proton's charge radius increases the proton's potential near the proton's origin by a factor of 100. Fortunately, the volume of this space scales with $r^3$ and the potential scales with $r$ so the total energies involved are ignorably small instead of scaling to infinity like you would expect from decreasing $r$ in the equation $V=\frac1{4\pi\epsilon_0}\frac qr$. This potential change affects little things like the electrostatic component of the Gibbs free energy of solvation of an ion. Chemistry still works the way we're used to. The slight differences in chemistry are unnoticeable next to the big differences in classical physics that come from everything being a hundred times denser.

BUT...increasing the mass of a proton does have big ramifications for nuclear physics. Would multi-nucleotide nucleii be more or less stable with heavier nucleons? I don't know and since your question is concerned about chemistry and electron clouds I'll leave that thorny bit to people with a better understanding of nuclear physics.

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If your more massive protons and neutrons have the same quantum numbers (baryon number, isospin, charge, etc.) as their normal counterparts, then it is likely that they will quickly decay to those normal particles plus energy in the form of photons. If they have different quantum numbers, then they’re not protons and neutrons at all, but new particles of some kind. Note that you can theoretically make heavier neutrons and protons by substituting a more massive quark from a higher generation for one or more of their up or down quarks, but they are extremely short-lived, basically for the reason above.

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