QUICK REFERENCE
- Symbol: Pu
- Atomic Number: 94
- Atomic Weight: [244]
- Element Classification: Actinide
- Discovered By: Glenn T. Seaborg, Arthur Wahl, Joseph W. Kennedy, and Edwin McMillan
- Discovery Date: 1940
- Name Origin: Named after the planet Pluto, following the pattern of naming elements after planets (like uranium for Uranus and neptunium for Neptune)
- Density(g/cc): 19.86
- Melting Point: 639.4°C
- Boiling Point: 3228°C
- Appearance: Silvery-white metal, tarnishes to a dull gray when oxidized
- Atomic Radius(pm): 151
Discovery
Plutonium was discovered in 1940 by a team led by Glenn T. Seaborg, Arthur Wahl, Joseph W. Kennedy, and Edwin McMillan at the University of California, Berkeley. The element was synthesized by bombarding uranium-238 with deuterons in the cyclotron at Berkeley, producing neptunium-238, which then underwent beta decay to form plutonium-238. This marked the second transuranium element to be discovered. The name “plutonium” was chosen to continue the tradition of naming new elements after planets, following Neptune with Pluto.
Relation to Other Elements
Plutonium is part of the actinide series, characterized by its complex electron configurations and multiple oxidation states, making it chemically versatile. It shares similarities with other actinides, such as being highly radioactive and capable of forming a variety of compounds. Plutonium-239, one of its most important isotopes, is a key fissile material used in nuclear weapons and as fuel in nuclear reactors due to its ability to sustain a chain reaction.
Natural Occurrence
Plutonium occurs in trace amounts in nature as a result of spontaneous fission of uranium-238 and neutron capture processes. However, the majority of plutonium is synthetically produced in nuclear reactors through neutron bombardment of uranium-238.
Uses
Plutonium has several critical applications, mainly in the field of nuclear energy and weaponry:
- Nuclear Weapons: Plutonium-239 is a primary material used in the manufacture of nuclear weapons due to its high rate of fission and the relatively small critical mass needed for a chain reaction.
- Nuclear Reactors: Plutonium-239 and other isotopes are used as fuel in certain types of nuclear reactors, including fast breeder reactors, which can create more fissile material than they consume.
- Radioisotope Thermoelectric Generators (RTGs): Plutonium-238, due to its long half-life and steady heat generation from alpha decay, is used as a power source in RTGs for spacecraft, providing electricity and heat for missions far from the Sun.
The discovery of plutonium significantly impacted the development of nuclear science, energy, and weaponry, playing a pivotal role in both civilian and military applications. Its handling and use are subject to strict controls due to its radioactivity and potential health risks.