CAS Number7440-61-1
PubChem CID23989
Atomic Radius156
Atomic Volume12.59
Atomic Weight238.029
Boiling Point4,131
Bulk Modulus
Crystal StructureBase Centered Orthorhombic
Covalent Radius196
Electrical Resistivity
Electron Configuration[Rn] 5f3 6d1 7s2
Electrons per shell2, 8, 18, 32, 21, 9, 2
Heat of Fusion14
Heat of Vaporization420
Ionization Potential6.194
Magnetic Ordering
Magnetic Susceptibility
Mass Number92
Melting Point1,132.2
Atomic Number238
Oxidation States3, 4, 5, 6
Poisson Ratio
Shear Modulus
Specific Heat Capacity0.116
Thermal Conductivity0.276
Van der Waals radius
Young's Modulus
Abundance in Earth's crust0.00018%
Abundance in Universe2×10-8%
U Uranium 92 238.02891 7 f 92 1132.0 3818.0 [Rn] 5f3 6d1 7s2 2 8 18 32 21 9 2 19.0 0.00018% Silver Orthorhombic 1.4 {"1":"597.6","2":"1420"} 598 +6,3,4,5 1.38 12.5 15.48 422.58 0.12 27.6 1 4.471×1099y AlphaEmission Solid, Conductor, Actinide, Radioactive, Natural yoo-RAY-ni-em Silvery-white, dense, ductile, malleable, radioactive metal. For many centuries it was used as a pigment for glass. Now it is used as a fuel in nuclear reactors and in bombs. Occurs in many rocks, but in large amounts only in such minerals as pitchblende and carnotite. B8vVZTvJNGk Uranium
Osmium was discovered in 1803 by English chemist Smithson Tennant in London.

Chemists who studied platinum dissolved it in aqua regia to create soluble salts and observed a small amount of a dark, insoluble residue.

Smithson Tennant analyzed the insoluble residue and concluded that it must contain a new metal. From the Greek word osme, meaning smell 92 1789 Martin Klaproth Germany Named after the planet "Uranus"

Isotopes of Osmium

Standard Atomic Weight


Stable Isotopes

234U 235U 238U

Unstable Isotopes

217U 218U 219U 220U 221U 222U 223U 224U 225U 226U 227U 228U 229U 230U 231U 232U 233U 236U 237U 239U 240U 241U 242U

Even low concentrations in air can cause lung congestion, skin damage, or eye damage
Osmium is the least abundant stable element in the Earth's crust
Osmium is used alloyed with other metals in the platinum group to produce very hard alloys.

Osmium alloys are used in the tips of fountain pens, instrument pivots, and electrical contacts

Osmium tetroxide has been used in fingerprint detection and in staining fatty tissue for optical and electron microscopy.