Plutonium is an actinide that has a silvery white color in its natural solid appearance. This element is known for its unusual chemical characteristics including the fact that it has six allotropes, is sensitive to atmospheric changes, and it become brittle with time due to its characteristic to self-irradiate itself. Plutonium has an atomic weight of 244, a melting point of 1182.9 °F, and a boiling point of 5842 °F. Plutonium is used to power pacemakers, and as a component in nuclear weapons.