⚛️ The quantum electron
A cloud of maybe
If you ask where an electron is before anyone has measured it, there’s no single answer yet.
You’ve probably seen an electron drawn as a tiny ball orbiting like a planet.
That picture is wrong.
Until you look, an electron has no place at all.
The setup
A better picture of the atom
In the middle is the nucleus, which holds all the heavy stuff, packed tight. Around it is a cloud. That cloud is one electron, spread across every place it could possibly be, all at once.
That might sound made up, so try it for yourself. Your turn: press Look and try to catch the electron. Watch where it turns up, then press it again.
Times you’ve looked
0
Last spot found: –
The cloud shows the odds. Where it’s thick, you’re likely to find the electron, and at the edges you’re unlikely to. Until you press Look there’s no dot at all, just the whole cloud. Each time you look, it turns up somewhere different.
the cloud = every possible positionthe dot = where this look caught it
Your guess
Before you look, where is it really?
In between two looks, when nobody’s measuring it, where is the electron? Have a proper think before you pick an answer.
When no one’s looking, the electron is…
If that’s hard to picture, think of a spinning coin on a table. While it’s spinning, it isn’t heads or tails yet, and it only becomes one when it falls flat. The electron before you look is like the spinning coin, while the first guess above is like a coin that’s already landed under your hand. The match isn’t perfect, because nothing in everyday life behaves quite like an electron, but it’s a good way to think about it.
One look gives you one dot, which doesn’t tell you much.
But a thousand looks…
…show you the shape of the cloud.
The why
Look enough times and the cloud appears
One look gives you one dot in a random spot, which doesn’t tell you much on its own. If you look hundreds of times, the dots pile up thickest where the cloud was thick and thinnest where it was thin. So the cloud is a map of the odds, and thousands of measurements let you see its shape. Scientists call that map an orbital.
Measurements piled up
0
Which cloud?
You’re building the round s-orbital. Electrons in different kinds of orbital have different-shaped clouds, and some are round while others are shaped like a dumbbell.
Next is one of the strangest experiments in science.
A single electron goes through two slits at the same time.
The why
The two-slit experiment
Fire electrons one at a time at a wall with two slits in it, and let them land on a screen behind. Each one lands as a single dot, like a particle, the way a thrown pebble would. So you’d expect two stripes behind the two slits. Fire some and see what actually builds up.
Peeking: off. Nobody is checking which slit each electron goes through. Press Fire and watch the pattern build.
You get stripes, like the pattern where ripples from two stones overlap in a pond. That can only happen if each electron went through both slits at once as a wave and interfered with itself. Now press Peek to put a detector at the slits that catches which one each electron used. The stripes disappear and you get two plain bands, because looking has changed what the electron did.
This explains something about you, too.
Every atom in you has these clouds of electrons around it.
You feel solid because these clouds can’t be squeezed into each other.
Superposition
What superposition means
This is the usual way physicists describe it. Until it’s measured, an electron is in all its possible places at once, and this is called superposition. When you measure it, it becomes somewhere, at a spot chosen at random, with the cloud setting the odds. Press the button to switch between the electron before and after it’s measured.
Before you look, the electron is a spread-out cloud of every place it could be at once.
Scientists still disagree about what this means, and they’ve been arguing about it for a hundred years. But every experiment so far agrees on what happens.
Everything around you is made of atoms…
…and every atom has electrons that are clouds of possibility until they’re measured.
Those clouds only settle on a spot when something measures them, and they’re what’s holding you up right now.
Pass it on
Next time someone draws an electron as a tiny ball orbiting like a planet, get them to press Look a hundred times. The dot keeps landing in different places, and the cloud it builds is the closest thing there is to “where the electron is”. Then show them the two-slit experiment, where one electron goes through both slits and interferes with itself, and see if they can work out why peeking wipes out the stripes.