CAS Number7440-04-2
PubChem CID23937
Atomic Radius135
Atomic Volume8.49
Atomic Weight190.23
Boiling Point5,012
Bulk Modulus
CategoryTransition metals
Crystal StructureSimple Hexagonal
ColorSlate Gray
Covalent Radius144
Electrical Resistivity
Electron Configuration[Xe] 4f14 5d6 6s2
Electrons per shell2, 8, 18, 32, 14, 2
Heat of Fusion31
Heat of Vaporization630
Ionization Potential8.438
Magnetic Ordering
Magnetic Susceptibility
Mass Number76
Melting Point3,033
Atomic Number190
Oxidation States-2, 1, 2, 3, 4, 5, 6, 7, 8
Poisson Ratio
Shear Modulus
Specific Heat Capacity0.13
Thermal Conductivity0.876
Van der Waals radius
Young's Modulus
Abundance in Earth's crust1.8×10-7%
Abundance in Universe3×10-7%
Os Osmium 76 190.23 8 6 d 76 3045.0 5030.0 [Xe] 4f14 5d6 6s2 2 8 18 32 14 2 22.6 1.8E-7% SlateGray Hexagonal 2.2 1.65 {"1":"840","2":"1600"} 840 106.1 +4,6,8 1.35 8.43 29.29 627.6 0.13 87.6 0 Solid, Paramagnetic, Conductor, TransitionMetal, Metal, Stable, Natural OZ-mi-em Hard fine black powder or hard, lustrous, blue-white metal. Used to tip gold pen points, instrument pivots, to make electric light filaments. Used for high temp. alloys and pressure bearings. Very hard and resists corrosion better than any other. Obtained from the same ores as platinum. AdX-T2Vv68Y Osmium
The existence of an element between neodymium and samarium was first predicted by Czech chemist Bohuslav Brauner in 1902.

Promethium was first produced and characterized at Oak Ridge National Laboratory in 1945 by Jacob A. Marinsky, Lawrence E. Glendenin and Charles D. Coryell.

It was produced by the separation and analysis of the fission products of uranium fuel irradiated in a graphite reactor. Named after the Greek Prometheus, who, according to mythology, stole fire from heaven 76 1803 Smithson Tennant England From the Greek word "osme" meaning "smell"

Isotopes of Promethium

Standard Atomic Weight


Stable Isotopes

184Os 186Os 187Os 188Os 189Os 190Os 192Os

Unstable Isotopes

162Os 163Os 164Os 165Os 166Os 167Os 168Os 169Os 170Os 171Os 172Os 173Os 174Os 175Os 176Os 177Os 178Os 179Os 180Os 181Os 182Os 183Os 185Os 191Os 193Os 194Os 195Os 196Os

Promethium is harmful due to its radioactivity
Promethium is the only lanthanide that has no stable isotopes
Promethium is also used in atomic batteries for spacecraft and guided missiles.

Promethium is also used to measure the thickness of materials by evaluating the amount of radiation from a promethium source that passes through the sample.

It has possible future uses in portable X-ray sources, and as auxiliary heat or power sources for space probes and satellites.