Its been a long time since ive studdied chemistry, I used to have a pretty decent understanding of it, but ive forgotten some of it. I remember that the energy produced from a fission reaction has to do with the number of bonds being broken, and that bonding energy released is obscenely high wich is why most fission reactions are performed with complex elements becuase they have more bonds to break, and are natrually unstable. But what is this concept of critical mass? How does a fission chain reaction start? What makes one perticular element a better fissile fuel?