An American Chemist named Glenn T. Seaborg discovered plutonium in 1941 at Berkeley University in California. The discovery of Plutonium was not announced until 1946 because America was at war with Japan and Germany. Plutonium was named after the planet Pluto, after the planet Neptune in the solar system and Neptune gave its name to Neptunium. Plutonium is a silvery metal that turns yellow when exposed to air. It is warm to the touch due to the releasing radioactive energy from it. The atomic number of Plutonium is 94. It has an average atomic mass of 244. The symbol for plutonium is Pu. Plutonium is a lot like calcium. This is why take its place in bones, breaking down marrow cells and in doing so causing leukemia.Plutonium appears very little in nature. It can be produced by bombarding uranium with the nucleus from a hydrogen ion. This hydrogen ion is called deuterium and so the nucleuses are called deuterons. There are 15 known isotopes of plutonium. They range from an atomic mass of 232 to 246. Plutionum-239 is thought to be the most important. It can be split into two parts called "fission fragments" that release large amounts of energy. It melts at 641 degrees Celsius and boils at about 3232 degrees Celsius. Plutonium is made in large amounts by nuclear reactors. Since it's easy to produce it is used a lot in nuclear weapons. An amount of Plutonium about the size of an orange is enough to fuel a nuclear reactor. It is also used as a battery in heart pacemakers. Furthermore, it has been used to power some forms of spacecraft. BibliographyEncyclopedia of science and technology, 7th edition. McGraw Hill, New York. Copyright 1992.Stwrtka, Albert. A guide to the elements. Oxford press, New York. Copyright 1996.Knapp, Brian. Uranium and other radioactive elements. Croiler, New York. Copyright 1996Encarta Computer Encyclopedia.