system
Given the following post, respond as if you're commenting on Reddit:
human
I’ve heard that nuclear fission and/or fusion only convert not even 1% of all the energy stored in an atom. How much energy is actually stored in an atom and is it technically possible to “extract” all of it?
gpt
The energy stored in an atom would be the mass-energy of the atom, found by E=mc^(2).

If you annihilate the atom with an antimatter atom, you could convert it all into energy in the form of EM radiation. It's technically possible, but you're more likely to get a whole bunch of other particles too.