According to Quantum-Mechanics, the ultimate solution to the question, of Wave-Particle Duality, no matter how deeply this solution is buried, lies in the idea, that Particles cause Waves. Hence, the particles are more-ultimately real, and waves are not. In certain cases such as phonons, this even extends beyond waves-in-a-vacuum, to sound waves, that can be modeled as quasi-particles.
One rule which this evokes is the notion, that if (A) causes (B) with certainty, then it cannot be true that (B) causes (A). And to my mind, this has presented the greatest challenge with Chemistry.
The way Chemistry is understood to work today, the electrons that were loosely stated to be orbiting the nucleus, are actually occupying Quantum-Mechanical states around the nucleus, thus merely being attached to the nucleus, and they occupy shells, which are subdivided into orbitals. Further, these orbitals have known wave-functions, that follow from QM. Hence, the s2 -orbitals are spherical, the p6 -orbitals are perpendicular, and the d10 and f14 -orbitals have the more-complex geometries, which are possible modes of resonance. If all the orbitals belonging to a shell are filled, then indeed the shell becomes spherical itself, and this is best exhibited with inert gasses, which therefore also have ideal cancellation of the nuclear charge at close distance, and which therefore also lack electronegativity. (:1)
The main point of confusion which is possible here, is in the fact that these orbitals and their wave-functions seemingly define the chemical and physical properties of the element, except for anything related to its mass. The suggestion follows, that since the electrical field of the nucleus is strong enough to manipulate the wave-functions, it can also end up displacing where the particle ultimately occurs. In so doing, this action on the orbital would seem to suggest that the wave-function can also be said to change the particle-parameters, thereby creating a contradiction with the way in which QM is currently taught.
There is a specific observation which we can make about this subject, which causes Chemistry to avoid contradicting QM by the width of a hair.
These s, p, d and f -orbital geometries are only thought to exist, if their electrons are unpaired. Each orbital is capable of holding up to 2 electrons, and an orbital which only holds 1 electron is said to be “half-filled”. It has these formally-defined properties when half-filled.
There has never been a precedence in Chemistry, in which a half-filled orbital can be shared by two atoms. But some sort of entity needs to be shared between 2 or 3 atoms, in order actually to form a bond, and in order to change position around either atom. (:2)
When orbitals are filled by 2 electrons each, these two electrons perform a dance which electrons are already famous for, in which both their spin-vector and their magnetic dipole moment pair up, to cancel out. This is also known as “spin-spin decoupling”, and causes the electron to resemble a Fermion less, resulting in some quasi-particle that resembles a fluid more – i.e. a massive Bose particle.
The same affinity causes electron-pairs to form Cooper Pairs, which ultimately result in superconductivity. But in Chemistry, it forms charge-droplets, which are able to change position on an atom or molecule, and which can be shared between 2 or 3 atoms, thus forming either the sigma-bond or the pi-bond known.
The important fact to understand, is that This quasi-particle does not represent a wave-function, and so its mutability also does not represent the mutability of a wave-function. This charge-droplet has mass.