|Appearance||silvery gray metallic; corrodes to a spalling black oxide coat in air|
|Standard atomic weight Ar, std(U)||238.02891(3)|
|Uranium in the periodic table|
|Atomic number (Z)||92|
|Electron configuration||[Rn] 5f3 6d1 7s2|
|Electrons per shell||2, 8, 18, 32, 21, 9, 2|
|Phase at STP||solid|
|Melting point||1405.3 K (1132.2 °C, 2070 °F)|
|Boiling point||4404 K (4131 °C, 7468 °F)|
|Density (near r.t.)||19.1 g/cm3|
|when liquid (at m.p.)||17.3 g/cm3|
|Heat of fusion||9.14 kJ/mol|
|Heat of vaporization||417.1 kJ/mol|
|Molar heat capacity||27.665 J/(mol·K)|
|Oxidation states||+1, +2, +3, +4, +5, +6 (an amphoteric oxide)|
|Electronegativity||Pauling scale: 1.38|
|Atomic radius||empirical: 156 pm|
|Covalent radius||196±7 pm|
|Van der Waals radius||186 pm|
|Spectral lines of uranium|
|Speed of sound thin rod||3155 m/s (at 20 °C)|
|Thermal expansion||13.9 µm/(m·K) (at 25 °C)|
|Thermal conductivity||27.5 W/(m·K)|
|Electrical resistivity||0.280 µΩ·m (at 0 °C)|
|Young's modulus||208 GPa|
|Shear modulus||111 GPa|
|Bulk modulus||100 GPa|
|Vickers hardness||1960–2500 MPa|
|Brinell hardness||2350–3850 MPa|
|Naming||after planet Uranus, itself named after Greek god of the sky Uranus|
|Discovery||Martin Heinrich Klaproth (1789)|
|First isolation||Eugène-Melchior Péligot (1841)|
|Main isotopes of uranium|
Uranium is a chemical element (a metal) on the periodic table. It has an atomic number of 92, which means that a uranium atom has 92 protons in its center, which is called a nucleus. Uranium that is dug out of the ground will be made from three different isotopes: three different types of uranium with different numbers of neutrons in their nuclei. Most of it is Uranium-238; uranium-235 is less common; uranium-234 is the rarest. Pitchblende is the main ore that is mined for uranium.
Uranium-235 can be used in nuclear reactors and nuclear weapons by making a nuclear chain reaction. This turns the uranium-235 into uranium-236 and splits the nucleus into two smaller nuclei. This makes two completely different elements with smaller atomic numbers. This process is called nuclear fission and creates lots of heat. This heat makes it very useful for making steam in nuclear reactors, or for making explosions with nuclear weapons. But most such weapons use Plutonium made from uranium-238. Uranium is a bit radioactive.
Uranium which has had its uranium-235 taken out of it is called depleted uranium. It is used in anti-tank weapons. Uranium can also be used as a dye for stained glass or pottery, which is how it was used before people found out that it was radioactive.
Uranium is a dangerous substance. Because Uranium is radioactive it is often seen with the hazard sign for radioactive elements, a group of three triangles with curved outer edges pointing in towards the middle (as you can see on the left). Some people believe that Uranium is light green, and glows, due to the way it is depicted in many movies. However, this is not true. Uranium is a shiny white metal, but is usually seen in its oxide form which is black. Spent or partially spent uranium fuel rods kept underwater, for example inside a nuclear reactor or in a spent fuel pool, can glow blue due to Cherenkov radiation. In addition to being radioactive, uranium is a heavy metal and is chemically toxic.
Characteristics[change | change source]
Uranium is a silvery white, weakly radioactive metal. It has a Mohs hardness of 6. It is malleable, ductile and slightly paramagnetic. It is strongly electropositive. It is a poor electrical conductor. Uranium metal has a very high density of 19.1 g/cm3.
Uranium metal reacts with almost all non-metal elements and their compounds. Hydrochloric and nitric acids dissolve uranium, but non-oxidizing acids other than hydrochloric acid dissolve the element very slowly.
History[change | change source]
Pre-discovery use[change | change source]
The use of uranium in its natural oxide form dates back to the year 79 CE. It was used in the Roman Empire to make ceramic glazes yellow. Yellow glass with 1% uranium oxide was found in a Roman villa on Cape Posillipo in the Bay of Naples, Italy. It was found by R. T. Gunther of the University of Oxford in 1912. In the late Middle Ages, pitchblende was extracted from the Habsburg silver mines in Joachimsthal, Bohemia (now Jáchymov in the Czech Republic). In the early 19th century, the world's only known sources of uranium ore were these mines.
References[change | change source]
- Meija, Juris; et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry. 88 (3): 265–91. doi:10.1515/pac-2015-0305.
- Morss, L.R.; Edelstein, N.M.; Fuger, J., eds. (2006). The Chemistry of the Actinide and Transactinide Elements (3rd ed.). Netherlands: Springer. ISBN 978-9048131464.
- Morss, L.R.; Edelstein, N.M.; Fuger, J., eds. (2006). The Chemistry of the Actinide and Transactinide Elements (3rd ed.). Netherlands: Springer. ISBN 9048131464.
- McGraw-Hill concise encyclopedia of science & technology (5th ed ed.). New York: McGraw-Hill. 2005. ISBN 0-07-142957-3. OCLC 56198760.
|edition=has extra text (help)
- CRC handbook of chemistry and physics, 2000-2001. Lide, David R., 1928- (81st ed ed.). Boca Raton: CRC Press. 2000. ISBN 0-8493-0481-4. OCLC 44440496.
|edition=has extra text (help)CS1 maint: others (link)
- "Uranium - Element information, properties and uses | Periodic Table". www.rsc.org. Retrieved 2020-11-20.