Uranium facts for kids

Quick facts for kids
Uranium, ₉₂U

Uranium
Pronunciation	/jʊəˈreɪniəm/ ​(ewr-AY-nee-əm)
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
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson Nd ↑ U ↓ (Uqh) protactinium ← uranium → neptunium
Atomic number (Z)	92
Group	n/a
Period	period 7
Block	f
Electron configuration	[Rn] 5f3 6d1 7s2
Electrons per shell	2, 8, 18, 32, 21, 9, 2
Physical properties
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)
Vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 2325 2564 2859 3234 3727 4402
Atomic properties
Oxidation states	+1, +2, +3, +4, +5, +6 (a weakly basic oxide)
Electronegativity	Pauling scale: 1.38
Ionization energies	1st: 597.6 kJ/mol 2nd: 1420 kJ/mol
Atomic radius	empirical: 156 pm
Covalent radius	196±7 pm
Van der Waals radius	186 pm
Spectral lines of uranium
Other properties
Natural occurrence	primordial
Crystal structure	​orthorhombic
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)
Magnetic ordering	paramagnetic
Young's modulus	208 GPa
Shear modulus	111 GPa
Bulk modulus	100 GPa
Poisson ratio	0.23
Vickers hardness	1960–2500 MPa
Brinell hardness	2350–3850 MPa
CAS Number	7440-61-1
History
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
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct 232U syn 68.9 y SF – α 228Th 233U trace 1.592×105 y SF – α 229Th 234U 0.005% 2.455×105 y SF – α 230Th 235U 0.720% 7.04×108 y SF – α 231Th 236U trace 2.342×107 y SF – α 232Th 238U 99.274% 4.468×109 y α 4.270 234Th SF 205.87 – β−β− – 238Pu

A small amount of uranium in a glass dish

Uranium is a special metal found on the periodic table. It is a chemical element with an atomic number of 92. This means a uranium atom has 92 protons in its center, called the nucleus.

When uranium is dug from the ground, it comes in three main types called isotopes. These types have different numbers of neutrons in their nuclei. Most of it is Uranium-238. Uranium-235 is less common, and Uranium-234 is very rare. The main rock mined for uranium is called Pitchblende.

Uranium-235 is very important because it can be used in nuclear reactors and nuclear weapons. It works by creating a nuclear chain reaction. This process, called nuclear fission, splits the uranium-235 nucleus into two smaller nuclei. This creates lots of heat. This heat is useful for making steam in nuclear reactors to produce electricity. It can also cause big explosions in nuclear weapons. However, most nuclear weapons use Plutonium, which is made from Uranium-238.

Uranium is also a bit radioactive. This means it gives off energy that can be harmful.

Radiation warning

Uranium that has had its Uranium-235 removed is called depleted uranium. It is used in special anti-tank weapons. Uranium was also once used as a dye for stained glass or pottery. People used it this way before they knew it was radioactive.

Uranium is a dangerous substance. Because it is radioactive, you often see it with the hazard sign for radioactive elements. This sign is a group of three triangles pointing inwards. Some movies show uranium as light green and glowing, but this is not true. Uranium is a shiny white metal. However, it is usually seen in its oxide form, which is black. Spent uranium fuel rods under water can glow blue due to Cherenkov radiation. Besides being radioactive, uranium is a heavy metal and can be toxic.

What is Uranium Like?

Uranium is a silvery-white metal that is slightly radioactive. It is quite hard, with a Mohs hardness of 6. It is malleable, meaning it can be shaped. It is also ductile, meaning it can be pulled into wires. Uranium is slightly paramagnetic and strongly electropositive. It does not conduct electricity very well. Uranium metal is very dense, weighing 19.1 grams per cubic centimeter.

Uranium metal reacts with almost all non-metal elements. Acids like hydrochloric and nitric acids can dissolve uranium.

Uranium-235 was the first isotope found to be fissile. This means its nucleus can be split easily. Other natural isotopes can also be split, but not as easily.

Only about 15 pounds (7 kg) of Uranium-235 can be used to make an atomic bomb. The atomic bomb dropped on Hiroshima, called Little Boy, used uranium fission.

How Uranium Was Discovered

The planet Uranus, which uranium is named after

People used uranium in its natural oxide form as early as 79 CE. In the Roman Empire, it was used to make ceramic glazes yellow. Yellow glass with 1% uranium oxide was found in a Roman villa in Italy. This discovery was made in 1912 by R. T. Gunther.

In the late Middle Ages, pitchblende was dug up from silver mines in Joachimsthal, Bohemia (now in the Czech Republic). In the early 1800s, these mines were the only known places to find uranium ore.

Images for kids

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  Various militaries use depleted uranium as high-density penetrators.

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  The most visible civilian use of uranium is as the thermal power source used in nuclear power plants.

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  Uranium glass glowing under UV light

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  Uranium ceramic glaze glowing under UV light Design and developed by Dr. Sencer Sarı

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  Antoine Henri Becquerel discovered the phenomenon of radioactivity by exposing a photographic plate to uranium in 1896.

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  Cubes and cuboids of uranium produced during the Manhattan project

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  The mushroom cloud over Hiroshima after the dropping of the uranium-based atomic bomb nicknamed 'Little Boy'

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  Uraninite, also known as pitchblende, is the most common ore mined to extract uranium.

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  Monthly uranium spot price in US$ per pound. The 2007 price peak is clearly visible.

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  Uranium in its oxidation states III, IV, V, VI

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  Uranium hexafluoride is the feedstock used to separate uranium-235 from natural uranium.

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  Cascades of gas centrifuges are used to enrich uranium ore to concentrate its fissionable isotopes.

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  World uranium production (mines) and demand

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  Yellowcake is a concentrated mixture of uranium oxides that is further refined to extract pure uranium.

See also

In Spanish: Uranio para niños