system
Given the following post, respond as if you're commenting on Reddit:
human
Is it possible to "add" protons to an atom in a lab/accelerator and discover new elements? And why does an atom having just an extra proton than another atom make the two completely different elements? What property of protons causes this, if any?
gpt
Atoms, for us humans anyway, are fundamentally electronic in nature, their nuclear structure more or less doesn't matter.

Take a pile of positive charge and stack up electrons in standing waves on top of that positive charge, and you get atoms. Electrons arranged in orbitals (spherical harmonics) basically stacked on top of the positive charge as densely as possible. Because they are waves they have a characteristic minimum size which is a standing wave of different periodicity et al that we know as orbitals. From our perspective it almost doesn't matter what is in the nucleus of an atom. It could be made of anything, as it happens compact positively charged clumps of baryonic matter is actually stable according to our Universe, so atomic nuclei are possible. They naturally attract electrons to them due to the strength of the electrostatic force, and then you have atoms.

The reason why different amounts of positive charge on the atomic nucleus makes such a big difference is because it impacts the structure and behavior of the clump of electrons that is attempting to sit on top of the nucleus. As the spherical harmonics increase in the number of lobes they have you also increase the number of different orientations that are separate from each other, and these essentially form a set of different places where electrons can "live" in an atom. Each of them end up with naturally different energy levels, and because of the nature of spherical harmonics this means that the energy levels are not evenly spaced.

This is where orbitals and shells and chemical behavior comes in. Each spherical harmonic can essentially hold two electrons, because electrons have spin and if their spins are opposite each other in the same spherical harmonic that means they still end up with different quantum numbers overall. If they attempted to be in the same spherical harmonic around the same atom (the same orbital) with the same spin orientation then they'd have the same quantum numbers, which isn't allowed due to quantum mechanical reasons (electrons are fermions and obey the Pauli exclusion principle).

Anyway, what this means is that you end up with different behavior of the electrons around an atom depending on the charge of the nucleus. For example, if you have a nucleus with a charge of two (like Helium) then two electrons can sit on top of that atom in their standing wave orbitals and exist quite happily in the lowest energy state for those electrons possible, the 1s orbital. Helium is a very stable and non-reactive atom precisely because any changes to its electrons would require a lot of energy. In contrast, Lithium has a nuclear charge of 3, so a neutral Lithium atom would have not only those 1s electrons in a tightly bound spherically shaped orbital but another electron in a larger 2s spherical orbital that has a node at the center. The outer solitary 2s electron is much less tightly bound to the Lithium nucleus so the amount of energy it takes to ionize Lithium to Li+ is comparatively little. In fact, it takes 4.5x as much energy to ionize Helium as it does to ionize Lithium. This is why Lithium will more readily form ionic bonds, because it's relatively stable in a configuration where it has a solitary positive charge.

Depending on their electronic configuration, atoms can sometimes end up sharing electrons with each other. This is where the "electron standing wave" (in this case a molecular orbital) encompasses two or more atomic nuclei. So, for example, if you have two Hydrogen atoms, each with a nuclear charge of 1, they can form a molecular orbital together (a so-called sigma s-s bond) which is effectively equivalent to overlapping 1s atomic orbitals. The single molecular orbital can house 2 electrons (because of the opposite spins thing) and that ends up with an "average" of only one electron per atom, leaving the molecule still neutrally charged. This forms a bond because if one of the nuclei at one end of the molecular orbital were to move it would experience an electrostatic force. If it were to move closer to the other nucleus then not as much of the electrons would shield the positive charge of the other nucleus and would experience a repulsive force due to like charges repelling. If it were to move outside of the molecular orbital "electron cloud" (or electron wave) then the other nucleus plus the two electrons would be overall negatively charged, which would result in an attractive force toward the other nucleus. This is how molecular bonds keep atomic nuclei "connected" to each other even though they are nestled inside electron waves.

These mechanisms give rise to the entirety of chemistry. Differently charged atoms result in different forces and different energy levels for electrons in various atomic and molecular orbitals, and that's what favors or disfavors the formation of ions, covalent molecular bonds, or the behavior of "noble gases".