An electron is a particle and a wave; it is ideally simple and unimaginably complex; it is precisely understood and utterly mysterious; it is rigid and subject to creative disassembly. No single answer does justice to reality. ~ Frank Wilczek
Swirling in an orbital cloud around a nucleus, at a distance 10,000 times that of the nucleus’ diameter, are perfectly round, negatively charged electrons. An electron has a mass estimated at 1/1,836th of a proton.
Individual electron orbitals are limited to pairs. An electron pair comprises 2 electrons in the same orbital, albeit with opposite spins.
The Pauli exclusion principle forbids fermions from simultaneously occupying the same space. Electrons are fermions. Despite the Pauli exclusion principle, there is a distinct probability of an electron being inside the nucleus of an atom.
To fly together, members of an electron pair have different angular momentums – a different spin makes for an orbital twin.
Electrons commonly escape their atomic bond and become free electrons, at least temporarily. Electron transitions between bound and free characterize chemical reactions.
An electron in motion generates a magnetic field in its wake; whence electromagnetism. Electrons possess a magnetic dipole moment: a polarity like a bar magnet. Supposedly, that is because an electron is a spinning smear of charge. Elementary electromagnetism stipulates that this creates a magnetic dipole field. The more complex actuality is not understood.
That electrons have an electric dipole moment is strongly suspected. Confirming that by isolating an electron has proven tricky.
A free electron will accelerate under the influence of an electric field and crash into whatever is in its path. This is handy for recruiting electrons into employment, but self-defeating for measuring elusive electron properties. So, experiments to date aimed at determining whether electrons have an electric dipole moment have been thwarted.
An electron having an electric dipole moment might doom the Standard Model. Consider time-reversal symmetry.
Supposedly, the laws of physics stay the same if time ran backward. But for a spinning electron, the north and south poles would swap. An electric dipole would accumulate charge at one pole; the inverse of which does not happen with time running forward. So, an electron with an electric dipole moment would violate time-reversal symmetry.
That would not be a first. Mesons are known CP violators and do not respect time-reversal symmetry. But to have the star of electromagnetism and the cornerstone of chemistry blithely skirt the fundamental principles of the Standard Model would bring the model’s reign to an end.
The strength of the electron’s magnetic field provides perhaps the most stringent and brilliantly successful comparison of theory and experiment in all of physical science, whereas the value of the electric field has never been measured. It is a mystery even to theory. ~ Frank Wilczek
There is a great irony at the heart of electronics. At a practical level, electrons provide a steady charge. At a more fundamental level, that charge is immeasurable.
There are also limits to electron reliability. Semiconductor fabrication has reached the point of nano wires only a hundred atoms wide. At that point, electrons behave like quantum waves. Electrodes to control electron flow create a mountainous terrain that electrons struggle with.
They bash against the walls, and sometimes reflect from the flanks of the mountain pass. They also sense each other’s presence. ~ Dutch quantum physicist Casper van der Wal
At the quantum level, electron flow is an incredibly complex interaction of various physical phenomena: indescribable by any single formula. Depending upon the environment, electrons may scurry about, with eddies that create resistance among themselves, or may flow with no friction whatsoever.
Maxwell’s unified field theory of electromagnetism is neat packaging that does not always apply. In some environs, the electrical and magnetic properties of electrons are divisible. Electrons may behave as fractional particles: splitting into a magnet and an electrical charge which can move freely and independently of each other. Electrons’ magnetic moment may split into 2 halves and move apart, albeit with extra-dimensional linkage.
Electrons amply illustrate how little we know about how existence is constructed.