Urán

Urán, commonly known as uranium, is a chemical element with the symbol U and atomic number 92. It is a dense, silvery-gray metal and a member of the actinide series. Uranium is naturally radioactive and occurs only in trace amounts in the Earth’s crust. It plays a central role in nuclear science and energy due to its fissionable isotopes.

Naturally occurring uranium consists mainly of three isotopes: U-238 (about 99.3%), U-235 (about 0.7%), and U-234 (trace). U-235 is fissile, meaning it can sustain a nuclear chain reaction, while U-238 is fertile and can be converted into plutonium-239 in reactors. In chemistry, uranium most often exhibits oxidation states of +4 and +6; the uranyl ion (UO2)2+ is a common species in solution. Uranium forms oxides such as UO2 and U3O8, as well as various fluorides and chlorides.

History and naming: Uranium was discovered in 1789 by Martin Klaproth, who named the element after the newly discovered planet Uranus. It was first isolated as a pure metal in 1840 by Eugène-Melchior Péligot.

Occurrence and production: Uranium occurs in minerals such as uraninite (pitchblende). It is mined commercially in countries including Canada, Kazakhstan, Australia, Namibia, Niger, and Russia. The ore is processed into yellowcake (U3O8) and then enriched to increase the U-235 content to levels used for reactor fuel. Depleted uranium is produced as a by-product and is used in shielding and some armor applications.

Uses and safety: The primary use of uranium is as fuel for nuclear reactors and research, providing a significant portion of the world’s electricity. It is also used in uranium-lead dating in geology and has historical applications in pigments and glass. Handling requires radiological safety measures due to long-lived radioactivity, and its production and use are regulated to prevent risks to health, safety, and nonproliferation.