What is Plutonium?
Plutonium is part of the actinide group on the periodic table. The plutonium atom has 94 electrons and 94 protons with 2 valence electrons in the outermost shell. There are 150 neutrons in the most abundant isotope.
Characteristics and Properties
Under normal conditions, plutonium is a hard, brittle and silvery metal. It is a poor conductor of electricity and heat. When exposed to air, it becomes covered with a dark gray oxidized layer.
All forms of plutonium are radioactive and decay into other elements over time. Most isotopes decay to uranium.
Plutonium-239 is one of the major fission elements. Fission means it can sustain a chain reaction of nuclear fission. This feature is very important in nuclear reactors and nuclear explosives.
Highlights of Plutonium:
| Symbol | Pu |
| Atomic Number | 94 |
| Atomic Weight | 244 |
| Classification | Actinide |
| Phase at Room Temperature | Solid |
| Density | 19.816 grams per cm cubed |
| Melting Point | 640°C, 1183°F |
| Boiling Point | 3228°C, 5842°F |
| Discovered by | Glenn Seaborg, Arthur Wahl, Edwin McMillan, and Joseph Kennedy in 1940 |
Where is Plutonium found on Earth?
Plutonium is an extremely rare element in the earth’s crust. It is so rare that for many years it was assumed that it did not occur spontaneously. The main source of plutonium comes from the use of uranium 238 in nuclear reactors. Large quantities are produced each year by this process.
How is Plutonium used today?
Plutonium is used both in nuclear reactors and in nuclear weapons. It was used to create the second nuclear weapon deployed during World War II, the “Fat Man” nuclear bomb dropped on Nagasaki, Japan.
How was Plutonium discovered?
Plutonium was discovered by a team of scientists from the Berkeley Radiation Laboratory in California in 1940. Glen Seaborg, Arthur Wahl, Edwin McMillan and Joseph Kennedy produced and isolated plutonium-238 from a uranium sample. The discovery of plutonium was kept secret until 1946 because of the Second World War.
Where did Plutonium get its name?
It was named after the dwarf planet Pluto (considered a separate planet at the time). This stems from a tradition that began when uranium was named after the planet Uranus.
Isotopes
Plutonium does not exist in nature and has no known stable isotope. The longest-lived isotope is plutonium-244, which has a half-life of just over 80 million years.
Interesting Facts about Plutonium
It can form up to seven different isotopes (crystal structure).
Renowned scientist Enrico Fermi claimed to have discovered element 94 in 1934, but it turned out to be a mixture of other elements, including barium and krypton.
It was once thought that plutonium did not exist in nature, but traces have been found in uranium ores.
The first plutonium production took place at Oak Ridge National Laboratory in Tennessee. It was designed for the Manhattan Project to build nuclear bombs.
It was once used to power pacemaker batteries, but has since been superseded.