Uranium,  ₉₂U

General properties
Pronunciation	/jʊəˈreɪniəm/ ​(ewr-AY-nee-əm)
Appearance	silvery gray metallic; corrodes to a spalling black oxide coat in air
Standard atomic weight (Ar, standard)	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	group n/a
Period	period 7
Block	f-block
Element category	actinide
Electron configuration	[Rn] 5f3 6d1 7s2
Electrons per shell	2, 8, 18, 32, 21, 9, 2
Physical properties
Phase at STP	U: 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	U: 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 (1/2) 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
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A small amount of uranium in a glass dish

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, the nucleus.

Uranium dug out of the ground is made from three different isotopes. The isotopes are 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.