What does an atom bomb do?

Answer 1

Without going into rigorous scientific detail, an atomic bomb works by nuclear fission. That is, large atoms - namely uranium or plutonium - are split into smaller atoms in an uncontrolled chain reaction. One atom splits, neutrons from that split strike and split more atoms, which release more neutrons, and so forth, in what is called a chain reaction. This releases a tremendous amount of energy all at once. Thus a single bomb, weighing no more than a few hundred pounds, explodes with the force of tens of thousands of tons of TNT.

When we look at a hydrogen bomb, which is also a type of nuclear weapon (though strictly not an atomic bomb), we see that it works by nuclear fusion. That is small atoms - namely isotopes of hydrogen - are fused together to make atoms of helium. This releases even more energy. Thus a hydrogen bomb has a force of hundreds of thousands, or even millions of tons of TNT. Fusion requires fantastic temperatures and pressures to occur. The only way to create those conditions is to set off one or more atomic fission bombs. Essentially, a hydrogen bomb is a nuclear fusion device that requires an fission bomb as a detonator.

Both types of bombs produce several effects: a blast wave, thermal (heat) energy, prompt (i.e. immediate) radiation, and fallout (long-term radiation), as well as intense electromagnetic disruption. The exact amount of each depends on the design of the weapon, its size, and where it was detonated.

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Answer 2

It splits atoms in a process called fission (not FUSION).