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Plutonium

The element 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
Plutonium is a member of the actinide group in the periodic table. Plutonium atoms have 94 electrons and 94 protons with 2 valence electrons in the outer shell. There are 150 neutrons in the most abundant isotope.

Characteristics and Properties

Under standard conditions plutonium is a hard, brittle, silvery metal. It is a poor conductor of electricity and heat. When exposed to air, it becomes covered in a dark gray layer of oxidation.

All forms of plutonium are radioactive and decay to other elements over time. Most isotopes decay to uranium.

Plutonium-239 is one of the main fissile elements. Fissile means that it can sustain a chain reaction of nuclear fission. This characteristic is important in nuclear reactors and nuclear explosives.

Where is it found on Earth?

Plutonium is an extremely rare element in the Earth's crust. It is so rare that for many years it was thought that it did not occur naturally. The main source of plutonium is 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 in both nuclear reactors and nuclear weapons. It was used to create the second nuclear weapon deployed during World War II which was the "Fat Man" nuclear bomb dropped on Nagasaki, Japan.

Plutonium has also been used as a power and heat source for spacecraft. It was used on the Voyager and Pioneer space probes as well as the Pathfinder Mars robot lander and the Curiosity Mars rover.

How was it discovered?

Plutonium was discovered by a team of scientists at the Berkeley Radiation Laboratory in California in 1940. Glen Seaborg, Arthur Wahl, Edwin McMillan, and Joseph Kennedy produced and isolated plutonium-238 from a sample of uranium. The discovery of plutonium was kept secret until 1946 because of World War II.

Where did plutonium get its name?

It was named after the dwarf planet Pluto (which was considered a full planet at the time). This followed from the tradition started when uranium was named after the planet Uranus.

Isotopes

Plutonium does not exist in nature and has no known stable isotopes. The longest-lived isotope is plutonium-244 which has a half-life of just over 80 million years.

Interesting Facts about Plutonium


More on the Elements and the Periodic Table

Elements
Periodic Table

Alkali Metals
Lithium
Sodium
Potassium

Alkaline Earth Metals
Beryllium
Magnesium
Calcium
Radium

Transition Metals
Scandium
Titanium
Vanadium
Chromium
Manganese
Iron
Cobalt
Nickel
Copper
Zinc
Silver
Platinum
Gold
Mercury
 Post-transition Metals
Aluminum
Gallium
Tin
Lead

Metalloids
Boron
Silicon
Germanium
Arsenic

Nonmetals
Hydrogen
Carbon
Nitrogen
Oxygen
Phosphorus
Sulfur
 Halogens
Fluorine
Chlorine
Iodine

Noble Gases
Helium
Neon
Argon

Lanthanides and Actinides
Uranium
Plutonium

More Chemistry Subjects

Matter
Atom
Molecules
Isotopes
Solids, Liquids, Gases
Melting and Boiling
Chemical Bonding
Chemical Reactions
Radioactivity and Radiation
 Mixtures and Compounds
Naming Compounds
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Separating Mixtures
Solutions
Acids and Bases
Crystals
Metals
Salts and Soaps
Water
 Other
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Science >> Chemistry for Kids >> Periodic Table


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