Question: how do you make atomic explosions ?

Josh Makepeace answered on 20 Jun 2013:

Thinking about atomic weapons is a bit scary, I have to say. I don’t like it when science is used in such a destructive way. That being said, I can tell you a bit about how they work!

Most nuclear weapons are built using very unstable, radioactive elements like uranium and plutonium. They’re unstable because the centre of the atom (the nucleus) is very large, and can fall apart (decay), giving off lots of energy. When one of these atoms decays, it gives off particles called neutrons. When neutrons hit another one of these atoms, they can make it decay, too. It’s a chain reaction.

If you have enough of the material there, the chain reaction can get out of control – that’s a nuclear explosion. More and more atoms decay, and cause even MORE atoms to decay. All the energy gets released at once, and you get an explosion.

So what normally happens is a normal explosive like TNT is used to push together two chunks of uranium or plutonium. The amount in each chunk is carefully calculated so that when the two chunks are brought together, there’s enough material to make an explosion. The products formed after the explosion are really dangerous, too. They are radioactive for a very long time after the explosion, causing all sorts of health problems.

I hope that these weapons are never used again, and I’m glad governments in the US and Russia are trying to cut down the number of these weapons they have.