Quick and Easy: How the Atomic Bomb Works

Since today's Digital Civilization lesson was on the atomic age, I just thought I'd give a quick lesson to readers about how the Atomic Bomb works.  I am basing this post off of what I learned in my modern physics class at BYU (Phscs 222) along with some supplemental study.  Please comment if what I say is confusing.  Here we go:

So the basic building block in the universe is the atom.  Here is a picture of an atom.  Notice how there is a core of red and blue balls.  These are representations of protons and neutrons.  The different elements on a periodic table have to do with how many protons an element has.  Each element can also have differing numbers of neutrons for that number of protons, and each variant is called an isotope.  Keep this in mind.

Now look at this image.  Notice  how there is a lot more stuff in the core (nucleus) of the atom.  Here is the basic idea: if the core has too much stuff in it (or an isotope is arranged with a certain number of neutrons), it becomes unstable and will split apart releasing energy.  The two split parts will go flying away from where the split (fission) happened.

Sometimes these atoms will just split randomly, but you can also trigger the atom to split by hitting it with something (a neutron).  Notice how when the atom splits, the split will create other neutrons that can go on to hit other large atoms and split them apart.

This is where we get to all the top secret stuff.  The trick that scientists needed to discover in the 1930s and 40s is how many of these large atoms do we need to put together in order for there to be a chain reaction: one atom splits which leads to atoms around it splitting, and so on.  Just one split doesn't release a lot of energy, but if we can get a whole bunch of them to split at the same time... BAM!  we have the atom bomb.  Turns out the secret amount (critical mass) need for uranium is ~52kg.

Now, if you want to cause an explosion, you will need some way of getting two stable amounts of uranium, perhaps two 30 kg pieces, and smashing them together to create a mass of uranium that is greater than 52kg.  This picture shows one of the basic ways that it can be done.  You have some kind of conventional explosion such as gunpowder explode to push one half into another.  This method was used in "Little Boy" which exploded over Hiroshima Japan.

Now you know the basics about how nuclear weapons work.  Please ask questions.

Watch the this video to see a fictionalized time when too much uranium was put together and caused a dangerous nuclear reaction.