Plutonium is a radioactive chemical element with the symbol Pu and atomic number 94. It is a silvery-gray metal that is part of the actinide series and is known for its use in nuclear reactors and atomic bombs. Plutonium is primarily produced in nuclear reactors from uranium-238 and has several isotopes, with plutonium-239 being the most significant for its fissile properties. Due to its radioactivity and toxicity, plutonium poses significant health and environmental risks. It has a long half-life, which means it remains hazardous for thousands of years. Proper handling and disposal are crucial to prevent contamination and ensure safety.