Have you ever thought about a substance so loaded with energy that had the same explosive effect as 20 million pounds of TNT? Now, imagine this material also to be a source of power that could be used, even in the present state of knowledge, to supply humanity's energy needs long after the world's resources of conventional fuels such as coal and petroleum have become exhausted. Adding to it is the materials, strange combinations of properties. Sometimes the material is as hard and brittle as window glass, and at the same time, it could be as soft and plastic as a lead. This material is called Plutonium. There must be some questions in your mind like, what is Plutonium? How is Pu element formed and produced? What are its properties? We will now try to answer all these questions one by one.
What is Plutonium?
Plutonium, also known as Pu element, is considered as the first human-made element to be produced in large enough amounts. It is a heavy metallic element (more than twice as dense as iron). When freshly prepared, its uncorroded surface has a bright, silvery appearance. While most metals are good conductors of electricity and heat, Plutonium is not. Its electrical conductivity (ability to conduct electricity) and its thermal conductivity (ability to conduct heat) are both exceptionally low.
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The image shows the position of the Pu element in the atomic table, where the Plutonium atomic number is 94.
Plutonium is a radioactive element that is not found in nature. Plutonium atomic number is 94, and its position in the Periodic Table shows that it is the sixth member in the series of elements called the "actinides," of which actinium, atomic number 89, is the first member. Plutonium is also one of the "trans-uranium" elements since it has an atomic number higher than that of uranium (number 92).
Physical Properties of Plutonium
Perhaps the most unusual physical property of Plutonium is its occurrence in six different crystal structure forms or allotropes, each in a specific, well-defined temperature range. It is not uncommon for elements to have more than one allotrope, but Plutonium is the only one with as many as six.
Chemical Properties of Plutonium
Plutonium is a highly reactive metal. It readily combines with oxygen to form plutonium dioxide (PUO2). Increasing the temperature of Plutonium exposed to ordinary air rapidly increases the oxidation rate. Therefore, the metal must be protected in some manner when it is heated.
Now that you are familiar with the Pu element, we will look at some Plutonium uses.
Applications of Plutonium
When it comes to this element, plutonium uses are very limited. Only two out of the five isotopes have specific applications. The Plutonium uses include, producing energy on earth and in space, and nuclear weapons. Some of the general Plutonium uses are as follows.
It acts as a source of energy to produce electricity.
It is used in nuclear reactors, where it is used as fuels.
It acts as a neutron source to calibrate neutron detection equipment.
Plutonium has been used as a threshold detector for determining neutron energies.
Certain Facts About Plutonium
During the second world war, Plutonium was used to make the nuclear bomb called “Fat Man”, which was used to bomb Nagasaki. The bomb nearly claimed the lives of 80000 people.
Under certain conditions, Plutonium pyrophoricity gives it a glowing ember look.
Plutonium is used to produce around one-third of the total energy produced in a nuclear power plant.
For deep space missions, Plutonium is used as a vital source of power.
The Primary fuel used in neutron reactors is Plutonium.
The half-life of Plutonium-244 is about 82 million years.
Plutonium emits gamma rays, neutrons, and beta particles.
FAQs on Plutonium
1. What is Plutonium and what are its key properties as per the periodic table?
Plutonium (symbol Pu) is a synthetic, radioactive chemical element with atomic number 94. It belongs to the actinoid series of the periodic table. Key properties include:
- Appearance: It is a bright, silvery-white metal that quickly tarnishes to a dull grey or olive green upon exposure to air due to oxidation.
- Radioactivity: All isotopes of plutonium are radioactive, primarily decaying through alpha emission.
- State: It is a solid metal at room temperature with an unusually high density.
- Reactivity: It is chemically reactive and can form various compounds and alloys with other elements.
2. How is Plutonium produced, since it is not naturally abundant?
Plutonium is produced artificially in nuclear reactors. The most common process involves bombarding Uranium-238 (U-238) with neutrons. The U-238 atom absorbs a neutron to become U-239. This unstable isotope then undergoes two rapid beta decays. First, it decays into Neptunium-239 (Np-239), which then decays into the fissile isotope Plutonium-239 (Pu-239).
3. What are the main applications of Plutonium in energy and technology?
Plutonium has several highly specialised applications due to its unique nuclear properties. Its main uses include:
- Nuclear Fuel: Plutonium-239 is a key fissile material used to generate power in some nuclear reactors, often mixed with uranium to create MOX (mixed oxide) fuel.
- Nuclear Weapons: The fissile nature of Pu-239 makes it a primary component in modern nuclear weapons.
- Power for Spacecraft: The isotope Plutonium-238 is used in radioisotope thermoelectric generators (RTGs) to provide long-lasting electrical power for deep space missions and rovers where solar power is not feasible.
4. What are the fundamental differences between Plutonium and Uranium?
While both are heavy, radioactive actinoid elements, Plutonium and Uranium differ significantly. Uranium is a naturally occurring element found in the Earth's crust and is only mildly radioactive. In contrast, Plutonium is almost entirely synthetic, found only in trace amounts in nature, and is intensely radioactive. Uranium is commonly used as a primary fuel in most nuclear reactors, whereas Plutonium is either a byproduct of uranium fission or used in more advanced fuel types like MOX.
5. Why is Plutonium considered exceptionally dangerous to handle?
Plutonium's danger stems from its intense radioactivity and its nuclear properties. It is a potent alpha emitter. If inhaled or ingested, these alpha particles can cause severe damage to internal tissues, leading to cancer and other serious health issues. Furthermore, certain isotopes like Pu-239 are fissile, meaning that a sufficient amount, known as a critical mass, can sustain an uncontrolled nuclear chain reaction, posing a significant risk of nuclear detonation. This combination of radiological toxicity and fissile potential requires extremely strict handling and security protocols.
6. How does Plutonium's chemical reactivity explain why it tarnishes in air?
Plutonium is a highly reactive metal that readily interacts with atmospheric oxygen. This process, called oxidation, causes its shiny, silvery surface to tarnish. When exposed to air, it forms a surface layer of various oxides, most commonly Plutonium dioxide (PuO₂). This oxide layer is passive and protects the metal from further rapid oxidation, but it gives the surface a dull grey or olive-green appearance. The fine powder of some plutonium compounds can even be pyrophoric, meaning it can ignite spontaneously in the air.
