Question: Are electrons really in shells?

Charlotte Slade answered on 21 Jul 2025:

That is an absolutely brilliant question, and the honest answer is one of the coolest and weirdest things in all of science: Yes, but not in the way we usually draw them!

The idea of electrons in neat, tidy shells, like little planets orbiting the Sun, is a fantastic first step. It’s a bit like a simplified map of the London Underground. It’s not perfectly geographically accurate, but it’s super useful for figuring out how to get from one place to another.

In reality, the quantum world is much stranger and more interesting.

Here are two analogies that might help paint a clearer picture:

The Library Floors (Energy Levels): The “shell” number is really a label for an energy level. Think of an atom as a library with different floors. An electron can be on the 1st floor, or the 2nd floor, or the 3rd floor. But it can never be in between, like on floor 1.5. It has to exist on one of these specific energy levels, or “shells.”

The Hyperactive Bee (The Electron’s Location): Now, for where the electron actually is on that floor. It’s not walking in a neat circle. Imagine a super hyperactive bee buzzing around a flower. You can’t point to exactly where the bee is at any single moment, but you can describe the blurry “buzz cloud” where the bee is somewhere.

An electron is like that hyperactive bee. It doesn’t have a fixed path. It exists in a “probability cloud” within its energy level. We know the shape of that cloud, but we never know the exact location of the electron inside it.

So, a “shell” isn’t a hard track like a railway line. It’s a label for a specific energy level (a floor in the library) that contains a fuzzy probability cloud (the bee’s buzz cloud) where the electron is likely to be found.

It’s one of the reasons quantum physics is so mind-bending and fun. The universe at its smallest level is built more on ‘maybes’ and ‘probablys’ than on simple certainties.