U-235

U-235 (Uranium-235) is a naturally occurring isotope of uranium, a heavy metal. It is notable because it is fissile, meaning it can sustain a nuclear chain reaction by splitting apart when struck by neutrons. This property makes U-235 essential in nuclear power plants and weapons, as it releases a large amount of energy during fission. In nature, U-235 is only about 0.7% of uranium, so it often needs to be enriched to increase its concentration for practical use. Its ability to produce energy from splitting atoms is the foundation of nuclear power generation.