Have We Got Atoms All Wrong?
What is the true nature of atoms? Do they really look like this?
Many of us know what an Atom looks like, Protons and Neutrons bound together with Electrons whizzing around them. If we were to take a picture of an Atom, is this what we would see? Or have we got them wrong?
Our understanding of Atoms has changed dramatically over the past 100 years. From Rutherford’s experiments on the nucleus to the discovery of Neutrons, we have uncovered the nature of the building blocks of the Universe. But, almost all of us at school were taught that Atoms were mostly empty, with a dense core and tiny Electrons orbiting in different energy levels.
But this picture is wrong, mainly because Electrons aren’t point-like particles. You see, Electrons are a lot more ‘fuzzy’ than that. They are tough to pin down.
This is due to their ‘Quantum Wave Function’, which is a complicated way of saying they exist as a field of probability, not as an individual particle. This sounds very very odd, but let me explain.
Let’s say we have an Electron on its own, no Atoms nearby or electromagnetic forces acting on it. Where the Electron is ‘located’ is where it is most likely to be, the further away from this point, the exponentially less likely the Electron is to be there. The rate at which this probability decreases, the further away you get, is known as the Quantum Wave Function of the particle.
This means that there is a very, very small chance that an Electron can pop out of existence here and instantly reappear on the other side of the Universe. However, the chances are so slim that it will virtually never happen.
You could say that the Electron keeps disappearing and reappearing in a manner that means it creates this field of probability (which is a common explanation for the Electron Cloud). But that isn’t entirely true, as the double-slit experiment showed.
The double slit experiment can use Photons of light or Electrons as the principle is the same with both particles. Photons also don’t exist as point-like particles but fields of probability.
The experiment sends a single Photon/Electron through two very close slits in a screen then lets the light/Electron beam shine on a second screen (shown in the image below). That’s right — a single particle at a time.
They do this in rapid succession, so you get a stream of single Photons/Electrons going through the double slits. All of their positions on the screen are then recorded, so you get a readout of their distribution on the second screen.
If these acted as point-like particles, you would expect to get an uninterrupted bright patch on the screen behind. This is because the particles must go through one or the other slit, and therefore they have nothing to interact with.
But you don’t see this at all, instead, you get an interference pattern like the one below.
This is because the particles’ Quantum Wave Function actually goes through both slits, making it constructively and destructively interfere with itself, as shown in the video below.
This all sounds very weird again, as Quantum physics always seems to be!
So let’s explain this from the beginning. As an Electron or Photon passes by you, we don’t see it as a point-like particle because of its’ Quantum Wave Function. Instead, it passes more like a wave, as the probability of finding it gradually increasing and then decreasing. This means that these particles actually act like waves (with a wavelength determined by it’s Quantum Wave Function, hence the name).
And just like waves, they can interfere with each other. So, if you have two streams of particles where the peaks and troughs meet, then you will see a constructive interference with a doubly strong signal. But if the peaks line-up with the other troughs, then you get destructive interference, and the signal completely cancels out. This is shown in the GIF below.
This is what causes that interference pattern seen in the double slit experiment, even though there is only a single Photon/Electron. The Quantum Wave function goes through both slits, acting as a wave, not a particle, effectively making two waves from the same particle! These then interfere with each other and we get the beautiful bands on the second screen.
This shows that we can’t think of Electrons as points; they occupy a fuzzy area of probability. So what does that mean for Atoms? Are these neat orbits of individual Electrons wrong? What about the different energy level orbits that we were taught in chemistry? Was all of that wrong too?
Let’s break this down and make it easy. Let’s start with how Electrons look around Atoms, then the different energy orbits, and finally what Atoms actually look like.
So, how does a fuzzy spec of probability orbit an Atom? Well, remember the wavelength the Electron has that caused the interference pattern? The same thing happens here; it is just wrapped around the Atom.
The Electron is still stuck to the nucleus by its charge; that part is still the same. Except, rather than orbiting the nucleus, the Atom contorts the shape of the Electrons probability field. This effectively means the electron wraps its’ Quantum Wave Function around the nucleus.
Rather than having a nice neat orbit where the electron is always the same distance away from the nucleus, it can instead be really close or really far away, or anywhere in between. You get a hazy cloud of Electron probability all around the Atom, this is known as an Electron Cloud.
What about all of the energy levels? Are they the same was we were taught in high school?
For those that don’t remember, Atoms have different energy ‘shells’ which the Electrons could orbit, these were repeating spherical ‘shells’ around the nucleus. If the Atoms had more energy, then the Electrons would orbit in the higher energy outer ‘shells’.
As you probably guessed, this can’t be true. If the Electrons don’t have a set orbital distance, then you can’t have different energy shells. The truth of energy shells is far more beautiful than anything we would dream of.
These shells aren’t concentric shells expanding out but complex bubbles of Electron Clouds. The different bubbles of Electron Clouds interact with each other, and this pushes them into many beautiful and bizarre shapes, such as the ones below:
While these are simulations, not images, it shows the weird bubble-like fuzzy nature of Atoms. They are surrounded by complex Electron Clouds that interact with each other to make beautiful symmetrical and strange shapes.
But the shapes of these orbits can be changed with different energy levels, as shown in the image directly above. The different Electrons’ Quantum Wave Functions can harmonise with each other as different Electrons take on more energy and change their Quantum Wave Function (effectively changing their ‘wavelength’). This means that a simple Atom like Hydrogen can have all these different Electron Cloud patterns, making the different energy levels and changing how the Atom looks.
These weird-shaped Electron Clouds are what gives chemical bonds their shapes. Each one is a connection point for elements to form bonds. With an Electron Cloud shaped like a clover, you have four connections. You could create a straight connection or a crooked one.
So if you could ‘take a picture’ of an Atom, what would you see?
You would see these fuzzy opaque shapes, some more spherical, others more complicated like an Atom in a kaleidoscope. Some of the Atoms would share these Electron Clouds as they form bonds, like Atoms holding hands. But the overriding thing that you would see is the fuzzy nature, these are beautiful, symmetrical but ultimately not very neat objects.
So the next time someone says that Atoms are mostly empty space, you can correct them and say that they are actually stuffed to the brim with Electron Clouds.
Now you know how some of the smallest parts of the Universe look, which is very different from the common understanding of them. But, this fuzzy ball view gives us an incredibly beautiful Atomic-scale world, with complex symmetrical shapes that look almost like intricate flowers. It just shows how deeply ingrained beauty is in nature and the Universe.