Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium radioactively decays, usually by …

Uranium-235 (235 U or U-235) is an isotope of uranium making up about 0.72% of natural uranium. Unlike the predominant isotope uranium-238, it is fissile, i.e., it can sustain a nuclear chain reaction. It is the only fissile isotope that exists in nature as a primordial nuclide. Uranium-235 has a half-life of 703.8 million years.

Chemically, uranium is fascinating. Its nucleus is so full of protons and neutrons that it draws its core electron shells in close. This means relativistic effects come into play that affect the electron orbital energies. The inner core s electrons move faster, and are drawn in to the heavy nucleus, shielding it better.

2025年1月25日 · uranium-235 (U-235), radioactive isotope of the element uranium with a nucleus containing 92 protons and 143 neutrons. Uranium-235 is the only naturally occurring fissile material; that is, the uranium-235 nucleus undergoes nuclear fission when it collides with a slow neutron (a neutron with a kinetic energy less than 1 electron volt).

Chemical element, Uranium, information from authoritative sources. Look up properties, history, uses, and more.

2025年1月15日 · uranium (U), radioactive chemical element of the actinoid series of the periodic table, atomic number 92. It is an important nuclear fuel. Uranium constitutes about two parts per million of Earth’s crust.

2023年8月16日 · Uranium is a vital component for the production of nuclear fuel, which is used in nuclear power reactors all over the world (Image: A. Vargas/IAEA). Uranium is a naturally occurring radioactive element, which has the atomic number of 92 and corresponds to the chemical symbol U in the periodic table.

Uranium has 92 protons in its nucleus. The isotope2 238U has 146 neutrons, for a total atomic weight of approximately 238, making it the highest atomic weight of any naturally occurring element. It is not the most dense of elements, but its density is almost twice that of lead.

2025年2月6日 · Uranium (chemical symbol U) is a naturally occurring radioactive element. When refined, uranium is a silvery-white metal. Uranium has three primary naturally occurring. isotopes: U-238, U-235 and U-234. background radiation in the environment. Uranium is used in nuclear power generation.

Like other elements, uranium occurs in slightly differing forms known as isotopes. These isotopes differ from each other in the number of neutron particles in the nucleus. Natural uranium (Unat) as found in the Earth's crust is a mixture of three isotopes: uranium-238 (U-238), accounting for 99.275%; U-235 – 0.720%; and traces of U-234 – 0. ...