How does simply splitting one atom expel so much energy? There’s no way that much energy could fit into a hydrogen atom. There’s only one electron, which has the energy. How does one atom make a big explosion?
In: 0
In terms of how much energy is in an atom… H-bombs work by using nuclear fission (splitting heavy atoms) and nuclear fusion (merging light atoms). Both of these processes can release energy.
How much energy? Splitting a single heavy atom like uranium releases about 200 MeV (million electron volts) of energy. That is not very much from a human point of view — about as much as it takes to visibly move a speck of dust. But from an atomic point of view it’s a lot of energy. To put it into comparison, when a molecule of TNT undergoes an energetic chemical reaction, it releases about 2 eV of energy. So a single atom of uranium splitting releases the same energy as 100 million TNT atoms.
Nuclear fusion reactions release less energy per atom than nuclear fission does. In a hydrogen bomb, a lot of the fusion reactions are between deuterium and tritium, two isotopes (different types of) hydrogen. These release around 18 MeV of energy. So a little more than 10X less than a uranium atom splitting. But hydrogen atoms are very tiny and uranium atoms are very large, so in terms of raw masses, hydrogen fusion releases about 3 times more energy than uranium fission does.
But again, if it was one or two atoms — still not much from a human point of view. We can do some very simple math using Google if we know the above numbers and some facts about the energy from an H-bomb. The larges US H-bomb released about 15 million tons of TNT equivalent worth of energy. 68% of that was from fission, the rest from fusion. (Why so much fission? In an H-bomb, the energy of a fission bomb is used to start the fusion reaction, which itself produces neutrons that can set off an even bigger fission reaction.) So that is 10.2 megatons of fission and 4.8 megatons of fusion. If we put [10.2 megatons of TNT / 200 MeV](https://www.google.com/search?q=10.2+megatons+of+TNT+%2F+200+MeV&oq=10.2+megatons+of+TNT+%2F+200+MeV+&aqs=chrome..69i57j6.8795j0j7&sourceid=chrome&ie=UTF-8) into Google, it converts the units of energy and tells that about 1.3 x 10^27 atoms must have been split with fission in that bomb. That is a huge number — 1,300 trillion trillions of uranium atoms. Similarly, if we put [4.8 megatons of TNT / 18 Mev](https://www.google.com/search?q=4.8+megatons+of+TNT+%2F+18+MeV&oq=4.8+megatons+of+TNT+%2F+18+MeV&aqs=chrome..69i57.7909j0j1&sourceid=chrome&ie=UTF-8) into Google it tells us that about 7 x 10^27 fusion reactions must have taken place, with twice as many atoms. So that’s 14,000 trillion trillions of hydrogen atoms.
Which is a lot of atoms. In terms of more intuitive units, that’s about 570 kg / 1250 lbs of uranium (and plutonium) and 96 kg / 210 lbs of hydrogen. The actual bomb would have had more uranium, plutonium, and hydrogen in it — it wasn’t 100% efficient, not everything fissioned or fuse — but it gives you a sense of how much material we are talking about here: a fair amount!
Latest Answers