The chemical symbol for uranium is U, and it is the element with atomic number 92 of the periodic table. It has 92 protons and 92 electrons, with a valence of 6. atom uranium has the highest atomic weight of any naturally occurring uranium. Uranium is about 70 % denser than lead, but less dense than gold. It is slightly radioactive.
Uranium is extracted from other uranium-bearing minerals, such as uranite. Uranium is separated from rocks through a chemical process.
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URANUS ISOTOPES
(SOURCE: http://herramientas.educa.madrid.org/tabla/7isotopos/u7.html)
Natural uranium consists of three types of isotopes: uranium-238 (238U), uranium-235 (235U) and uranium-234 (234U). Of each gram of natural uranium 99.284 % of the mass is uranium-238, 0.711 % uranium-235,2and 0.0085 % uranium-234. The ratio uranio-238/uranio-235 is constant in the earth's crust
PROPERTIES OF URANIUM
Atomic mass: 238u
nºCAS: 1333-74-0
Density: 19,050 kg/m3
Atomic radius (calc): 156 pm (Bohr radius)
Group, period, block: -, 7, f
Name, symbol, number: Uranium, U, 92
Ordinary status: Solid
Boiling point:4404 K (4131 °C)
Melting point: 1405 K (1132 °C)
RADIOACTIVITY. URANIUM TOXICITY
A person can be exposed to uranium (or its radioactive derivatives such as radon) by inhaling airborne dust or by ingesting contaminated food and water.
Uranium is not only weakly radioactiveis a highly toxic metal. The normal functioning of the kidney, brain, liver, heart, and other systems can be affected by exposure to uranium.
URANIUM 235. NUCLEAR ENERGY
The 235U is used as fuel in nuclear power plants and in some nuclear weapons designs. Uranium-235 is distinguished by being the only element found in nature that is a fissile isotope, i.e., an isotope that is capable of undergoing fission with free neutrons of any energy.
Uranium is enriched to produce uranium with a higher proportion of uranium 253. Natural uranium is composed mainly of the isotope 238U, with a proportion by weight of about 0,7 % of 235U. Through an isotope separation process, uranium-235 and uranium-235 are separated and enriched to obtain a material with a higher percentage of uranium-235.
The most commonly used system in nuclear power plants uses the uranium as fuel. Specifically, Uranium 235 from enriched uranium is used which is subjected to fission in the reactors. In this process the nucleus of the atom The uranium atom is bombarded with neutrons and is broken into two atoms half the size of the uranium atom, releasing two or three neutrons which strike neighbouring uranium atoms, which break apart again, causing a chain reaction.
OTHER USES OF URANIUM
- In structural parts for aeronautics and satellites, thanks to its high density.
- The isotope 238U is used to estimate the age of the Earth, thanks to its long process of radioactive decay.
- The 238U is converted to plutonium in breeder reactors. Plutonium can be used in reactors or in nuclear weapons.
- Some photographic chemicals (uranium nitrate).
- Shielding against high-penetration radiation due to its high atomic weight. Also used as armour in battle tanks.
- It is used in X-ray benches, to make high-energy X-rays.