why are radioactive elements used in ission bombs?

Answer 1

I assume you mean "fission bombs." The whole concept of nuclear fission depends on the instability of your explosive element. It takes a certain amount of energy to hold an atom together, and the amount of energy necessary to hold any given isotope together varies depending on how many particles are in the nucleus and their orientation with respect to one another (the geometry of the nucleus) Elements or isotopes that are more stable are in the right configuration to hold themselves together without a lot of effort -- they want to stay that way, and you actually have to expend a lot of energy to get them to separate and break down into smaller parts. Less stable isotopes want to become more stable, and the easiest way to do that is to shed excess particles until it achieves a configuration that is lower in energy requirements. It can do this one of two ways: 1) by emitting radioactivity in the form of electrons (beta particles), bigger chunks (alpha particles) or converting excess mass into energy (electromagnetic radiation or gamma rays) (there are others, but we won't go into those today) or 2) through nuclear fission, whereby the element breaks apart into two or more smaller atoms that are more stable than the parent, usually also emitting an array of smaller particles or electromagnetic radiation. So the unstable elements that are radioactive, by the very virtue of their instability, make them the only real choice for fission bombs, because they are most easily fissionable in the first place.

Answer 2

Just because isotopes are radioactive does not mean they can be used to make a bomb. In fact, most radioactive isotopes could not be used to make a bomb. Also Uranium-235 and Plutonium-239 have really long half lives compared to a lot of radioactive material. This means that they will have lower activities than most other radioactive material and can be considered less radioactive.

In order to make a bomb start you need some sort of neutron source which requires radioactive decay the releases neutrons. The U-235 or Pu-239 will then multiply the number of neutrons through fission.

Answer 3

Trishaann said it correctly. Those heavier elements that are radioactive are more unstable. It doesn't take much for them to undergo fission, therefore it's easier to get a chain reaction started with them. So more energy is released.

If we control the reaction we can make a power plant with the fission process, but if we want to make a bomb, we don't try to control the process. We allow it to go BOOM.

Answer 4

Trishaan is right.

Answer 5

radioactive = unstable = bigger/easier boom