Electrons in Stable Atoms -Do They Exist ?

Big difference from the old Bohr model of the atom, to atomic quantum mechanical orbitals. Think of them exhibiting particle-wave duality, even when separate from an atom (in space) existing as wave-like packets of mass-energy. Yes they exist, and yes they carry angular momentum as well as "spin", and yes, they carry a negative charge.

They also have other quantum properties.

In molecules (including crystals of insulators, conductors, semiconductors, and semi-metals) electrons are in molecular orbitals, and for the sake of some understanding can be considered in Fermi states called conduction energy bands, valence energy bands. The populations of these bands determines the electrical characteristics of the material. In semiconductors, the population of the conductance band is limited by thermal population of the conduction bands, any dopant atoms present, etc.

Electric and magnetic fields have an influence on conduction bands - ever heard of Hall effect devices?

Also consider that electrons with high energy (outside of atoms) are called Beta particles.

It's all here....

https://en.wikipedia.org/wiki/Electron

I think it's easier to think of, or to visualize, an electron in an atom as a 'standing wave'. Rather than being a single particle orbiting the nucleus like a planet around the sun, it's a wave distributed all around the nucleus. It's 'location' isn't really a point, it's a distribution 'cloud' of probability around the nucleus.

it's all speculation. Neils Bohr said atoms don't exist until they are observed. You can't observe electrons, therefore.... Who cares, anyway?

if() = null

Try telling that to an electrical cabinet with an arc flash of 40 cal/cm² incident energy from 18-24 inches distance! (NO PPE made for that much incident energy.)

"I was brought up 60 and more years ago on atoms where the nuclei were surrounded by concentric spheres,"

Actually only the s-orbitals (the first sub-orbital in each shell) are spherical. The p, d & f sub-orbitals are dumbbell shaped, with the arms along the x, y & z axes. Most bizarre of all, is the d_z² which has a "doughnut" around the center point. No doubt a theoretical physicist can explain why. Below shows the five d sub-orbitals:

One interesting implication about the spherical s-level sub-shell is that the electron(s) (2 max) can reside anywhere within that sphere, including the nucleus itself - if only momentarily.

The interesting point many people miss, is that once the f orbitals are completely occupied, the resultant is still spherically symmetric.

Yes, they exist within the atom. But due to their wave properties, they behave rather strangely within the atom where only energies with an integral number of wavelengths in the available space are allowed. (Higher energy means shorter wavelength).

The Bohr atom is not a good picture. Electrons don't jump between orbits. What happens is that the resonance mode changes to one requiring a different energy. The energy difference is absorbed or radiated by a photon.

Here is a real world metaphor. A bugle is a brass horn without valves. Only certain notes can be played that correspond to an integral number of sound standing waves within the brass pipe of the instrument. By tightening his lips, the bugler can play a higher note (higher harmonic) with a shorter wavelength.

Bugle:

Playable notes:

Standing Waves: