Uranium
Definition and meaning of Uranium in chemistry.
Uranium is a heavy, weakly radioactive metal characterized by the symbol U and atomic number 92. It is a silvery white element belonging to the actinide series and boasts the highest atomic weight of any primordial element. Naturally occurring uranium is composed primarily of two isotopes, uranium-238 and the fissile uranium-235.
In more detail
Situated prominently in the actinide series of the periodic table, uranium is a dense, reactive metal that slowly oxidizes in ambient air to accumulate a dark, protective layer of uranium oxide. It is relatively abundant in the Earth crust, routinely discovered in widespread minerals like uraninite and pitchblende, and exists in massive total quantities dissolved within the global oceans. Uranium is primarily renowned for its unique nuclear properties, specifically the unique ability of the rare uranium-235 isotope to independently sustain a continuous nuclear fission chain reaction. When bombarded with slow neutrons, the heavy uranium-235 nucleus violently splits into lighter elemental fragments, releasing vast quantities of thermal energy alongside additional neutrons. Chemically, the element exhibits multiple complex oxidation states ranging from +3 to +6, with the hexavalent uranyl ion UO22+ being highly stable and prevalent in natural water systems. Due to its extreme density, the depleted byproduct of uranium enrichment is heavily utilized for specialized non-nuclear applications like aircraft counterweights and radiation shielding.
Key facts
| Field | General Chemistry |
|---|---|
| Symbol | U |
| Atomic number | 92 |
| Atomic mass | 238.03 u |
| Category | Actinide |
| State at room temperature | Solid |
| Melting point | 1132 degrees Celsius |
| Density | 19.1 grams per cubic centimeter |
Enriched uranium is the primary fuel used globally in commercial nuclear power plants to generate massive amounts of electricity through controlled fission reactions.
Frequently asked questions
What is the difference between depleted and enriched uranium?
Enriched uranium has an artificially higher percentage of the fissile uranium-235 isotope, whereas depleted uranium has most of this specific isotope removed.
How is uranium used to generate commercial electricity?
In a nuclear reactor, the fission of uranium atoms produces massive amounts of heat, which boils water to create high pressure steam that drives electricity generating turbines.