Actinides are a series of 15 chemical elements in the periodic table, ranging from actinium (atomic number 89) to lawrencium (atomic number 103). These elements are known for their radioactive properties and are typically found in nature in trace amounts. They are all metals and have similar properties, including the ability to form complex compounds. Most actinides are used in nuclear applications, such as nuclear reactors and nuclear weapons. The most well-known actinide is uranium, which is essential for nuclear energy production. Another notable actinide is plutonium, used in both energy generation and military applications.