Nuclear weapon
A 'nuclear weapon' is a weapon that suddenly releases the energy in the nucleus of certain types of atoms. When triggered, these devices release a huge amount of energy in the form of an explosion. Nuclear weapons are very powerful, and one nuclear weapon can destroy a city. They get their energy by changing some of their matter into energy. This is called a nuclear explosion. Nuclear explosions are difficult to ignite and control, and require uranium or plutonium that has been enriched for reactive isotopes. These isotopes are not concentrated enough in natural uranium to cause explosions.