I mean, I get the repercussions, but if they are so insanely small, how do you pull it apart? How do you only get one at a time done too – there must be bazillions in any one area so do they split a specific one or it’s just the first one along?
In: Physics
A couple of people have already pointed out that scientists don’t split individual atoms… they just “spray and pray” in a particle accelerator like the LHC… and in a nuclear reactor or a nuclear bomb it’s a random process that naturally happens when you put enough uranium-235 atoms close together:
U-235 is naturally unstable, occasionally an atom falls apart just because it does; the neutron it releases has loads of energy and if it’s close to loads of other densely packed U-235 atoms it’s likely to set off another atom… everything sets everything else off and kaboom.
Interestingly / crazily, it looks like there might have been at least one [naturally-occurring “nuclear reactor” on Earth](https://www.youtube.com/watch?v=yS53AA_WaUk) – a natural deposit of uranium rich enough that a limited chain reaction got going?
Having said that, I know this if different but [IBM have made an animation by moving individual atoms around](https://www.youtube.com/watch?v=idn28jMrtcA) and taking pictures of them. And that’s pretty cool. But atomic nuclei are held together so strongly that if you had a single atom in a grip, I’ve got no idea how you’d get enough energy in one place to hit it hard and split that one atom?
The quantum forces have to be overcomed, specifically the strong nuclear force and we do this by launching atoms in opposite directions and accelerating them to near the speed of light. To increase the chances of a collision, we have to use more atoms. The result isn’t always what you want, which is why scientists take months to make enough of a new element or to study a specific particule. Luck is a big part of bring a particule scientist.
It’s a chain reaction. You take a few heavy atoms with large, unstable nuclei, and you spray some fast moving neutrons. One of them will randomly hit a random one of the atoms, causing its nucleus to break, which will release even more fast moving neutrons that can collide with other atoms and so on. The rate of the fission can be controlled, if you want it faster you inject more neutrons, if you want it slower you put something like heavy water to damp and slow down the neutrons
Atoms are split by shooting them with neutrons. The atom absorbs the neutron, becomes unstable, and splits in two, releasing some more neutrons.
Each neutron can only split a single atom – the first one it hits at the right angle and speed. In any nuclear reactor (or bomb), there are many of these reactions going on at the same time, though.
Many are split at once. The trick is to have a big atom, and hit it with the fast moving smaller atom. And it out when you split one, it splits into fast moving smaller atoms. They slow down pretty quick though – but if there are enough more of the original bigger atom in the vicinity, they could be hit and split and create more small…. And so on. The trick then is twofold: have enough big atoms together that when one splits it’s more likely to hit others and repeat the process. And get the process started.
And starting the process is just a matter of waiting, because atoms sometime split naturally. The bigger they are, the more likely that’ll happen.
It’s like breaking a rack with the cue ball. Except each ball in the rack goes on to break a new rack, etc. Causing the chain reaction. Exponential growth gets billions of atoms being split at once in a nuclear explosion. In a reactor there are control rods that absorb some of the neutrons to keep the reaction tampered.
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