A group of electrons orbiting at roughly the same distance from the nucleus is called an electron shell.

Here's a breakdown:

* Electron shells: These are regions of space around the nucleus where electrons are likely to be found. They are not fixed orbits like planets around a star.

* Energy levels: Each electron shell corresponds to a specific energy level. Electrons in higher shells have more energy than those in lower shells.

* Subshells: Within each shell, there are also subshells that are further divided based on the shape of the electron's orbital.

It's important to remember that the Bohr model, which depicts electrons orbiting the nucleus in fixed circular paths, is a simplified model. The modern quantum mechanical model describes electrons as existing in probability clouds, with their exact location at any given time being uncertain.