Difference Between Plutonium and Uranium

Main Difference – Plutonium vs Uranium

Transuranium elements are chemical elements that have an atomic number greater than 92, the atomic number of Uranium element. All these transuranium elements are unstable and undergo radioactive decay. Plutonium is a transuranium element that has the atomic number 94. Uranium is also considered as a radioactive element because of its instability. This property of undergoing radioactive decay causes Plutonium and Uranium to be used as components in explosives and energy sources. The main difference between Plutonium and Uranium is that Plutonium is highly radioactive whereas Uranium is weakly radioactive.

Key Areas Covered

1. What is Plutonium
      – Definition, Properties, Radioactivity
2. What is Uranium
      – Definition, Properties, Radioactivity
3. What is the Difference Between Plutonium and Uranium
      – Comparison of Key Differences

Key Terms: Plutonium (Pu), Radioactive Decay, Transuranium, Uranium (U)

What is Plutonium

Plutonium is an artificial chemical element that has the atomic number 94 and symbol Pu. In the periodic table of elements, Plutonium can be found in the actinide series among f block elements. At room temperature and pressure, it is in the solid state. The electron configuration of this element can be given as [Rn]5f⁶7s². Therefore, it has six electrons in the f orbital.

Figure 1: Atomic Structure of Plutonium

The relative atomic mass of Plutonium is given as 244 amu. The melting point of Plutonium has been found as 640^oC. But it has an unusually high boiling point, which is about 3228^oC.There are three major synthetic isotopes of Plutonium. They are ²³⁸Pu, ²³⁹Pu, and ²⁴⁰Pu. Plutonium is a bright silvery gray metal. But it can be quickly oxidized obtaining a dull gray color.

Plutonium is a highly radioactive element. It tends to undergo alpha decay, which involves decay through releasing alpha particles. ²³⁹Pu and ²⁴¹Pu (trace) are fissile. This means they can sustain in a chain reaction of nuclear fission. It is important for these isotopes to be used in nuclear weapons.

The half-life of a radioactive material is the time taken for a sample of that element to become half of the initial mass through radioactive decay. ²³⁸Pu has a half-life of 88 years. ²⁴¹Pu has a half-life of 14 years. Other isotopes of Plutonium have considerably very high half-lives. Therefore, ²³⁸Pu and ²⁴¹Pu are the most unstable isotopes of Plutonium.

Plutonium generally has four oxidation states. They are +3, +4, +5 and +6. The compounds of these oxidation states are colorful. The color of the compound depends on the oxidation state of Plutonium. Although very trace amounts of ²³⁸Pu and ²³⁹Pu can be found in nature, these amounts are negligible. It is obtained mostly as an artificial element by producing it from ²³⁸U (Uranium-238).

What is Uranium

Uranium is a chemical element that has the atomic number 92 and the symbol U. It is weakly radioactive. The appearance of Uranium is silvery gray. The atomic mass of Uranium is about 238.03amu for the most abundant isotope of Uranium. It is located in the f block of the periodic table and belongs to the actinide series. The electron configuration is [Rn]5f³6d¹7s². At room temperature and pressure, it is a solid metal.

The melting point of Uranium has been found as 1132^oC. The boiling point of Uranium is about 4131^oC. Uranium metal is ductile and paramagnetic. (Ductile – Can be drawn into thin wire-like threads. Paramagnetic- Attracted to magnetic fields.).

Figure 2: A Uranium Metal “Biscuit”

There are several isotopes of Uranium. ²³⁸U is the most abundant isotope (abundance is about 99%) among them.  ²³⁴U and ²³⁵U can also be found in considerable amounts. These isotopes of Uranium have very high half-lives. Therefore, Uranium is considered as a weakly radioactive element. ²³⁵U is special because it is a fissile element.

Slats of many oxidation states of Uranium are water soluble. The most common forms are U⁺³and U⁺⁴. Apart from that, Uranium can form oxides and carbonates that are solid compounds. When proper conditions are provided, Uranium can form fluorides of Uranium such as UF₄ and UF₆. The major uses of Uranium includes nuclear reactors and nuclear weapons.

Difference Between Plutonium and Uranium

Definition

Plutonium: Plutonium is an artificial chemical element that has atomic number 94 and the symbol Pu.

Uranium: Uranium is a chemical element that has the atomic number 92 and the symbol U.

Transuranium Elements

Plutonium: Plutonium is a transuranium element.

Uranium: Uranium is not a transuranium element.

Radioactivity

Plutonium: Plutonium is highly radioactive.

Uranium: Uranium is a weakly radioactive element.

Occurrence

Plutonium: The natural occurrence of Plutonium is negligible.

Uranium: Uranium is a naturally occurring element.

Number of f Electrons

Plutonium: Plutonium has six f electrons.

Uranium: Uranium has three f electrons.

Half-life

Plutonium: The half-life of Plutonium is comparatively very low.

Uranium: The half-life of Uranium is comparatively very high.

Boiling Point

Plutonium: The boiling point of Plutonium is 3228^oC.

Uranium: The boiling point of Uranium is about  4131^oC.

Conclusion

Plutonium and Uranium are elements that are found in the actinide series of the periodic table. They are different from each other in several properties as discussed in this article above. The main difference between Plutonium and Uranium is that Plutonium is highly radioactive whereas Uranium is weakly radioactive.

References:

1. “Plutonium – Element information, properties and uses | Periodic Table.” Royal Society of Chemistry – Advancing excellence in the chemical sciences, Available here. Accessed 30 Aug. 2017.
2. “Transuranium element.” Wikipedia, Wikimedia Foundation, 11 Aug. 2017, Available here. Accessed 30 Aug. 2017.
3. “Uranium.” Wikipedia, Wikimedia Foundation, 27 Aug. 2017, Available here. Accessed 30 Aug. 2017.

Image Courtesy:

1. “94 plutonium (Pu) enhanced Bohr model” By Ahazard. sciencewriter – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Ames Process uranium biscuit” By Unknown – Ames National Lab (see OTRS) (Public Domain) via Commons Wikimedia