Radioactive elements are substances that emit radiation as they decay. This process occurs when the nucleus of an unstable atom breaks down, releasing energy in the form of particles or electromagnetic waves. Common examples of radioactive elements include uranium, radium, and plutonium. These elements are often found in nature and can be used in various applications, such as energy production and medical treatments. The radiation emitted by radioactive elements can be harmful to living organisms, which is why safety precautions are essential when handling them. Some radioactive elements have long half-lives, meaning they remain hazardous for extended periods, while others decay quickly. Understanding these elements is crucial for managing their use and minimizing risks to health and the environment.