Osmium is an exceptionally dense platinum-group metal used in very hard alloys and specialized catalysts. It occurs with other platinum metals and can be recovered during nickel refining. Osmium metal and its volatile, toxic oxide differ sharply, making chemical identity essential to understanding their behavior.
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AN ELEMENT IN CONTEXT
Why use an osmium-containing hard alloy at a small wearing surface?
Osmium-containing hard alloy
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Identify the contact requirement
A pen point or instrument component may face repeated contact with another material. The small working region needs appropriate resistance to wear.
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OsFORM → INTERACTION → CONSEQUENCE
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Atomic identity, reference properties and structure models
INTERACTIVE 3D76 visible sites
An electron censusDrag to rotate · scroll or pinch to zoom
[Xe] 4f14 5d6 6s2. Grouping electrons by principal shell connects the neutral-atom configuration to periodic-table patterns.
What this representation means
A three-dimensional counting diagram. Dots are count markers, not measured electron positions; spherical placement and spacing are arbitrary. There are no electron trajectories here. Orbitals describe quantum states.
Smithson Tennant investigated the residue left during platinum processing in 1803 and distinguished osmium and iridium. Osmium's name refers to the odor of an formed in that chemistry, not to a general smell of every metal sample. Much later, osmium-based chemistry contributed to the work recognized by the 2001 chemistry Nobel Prize, connecting an early analytical clue to controlled molecular transformations.
1803
Osmium distinguished
Tennant identified osmium within platinum-processing residue.
2001
Catalytic oxidation recognized
Sharpless’s Nobel-recognized work included osmium-based asymmetric oxidation chemistry.
Osmium occurs with other platinum-group metals, sometimes in natural such as osmiridium. Recovery is associated with processing complex and nickel-refining streams. Its presence in a mixed metallic or residue is therefore a more useful resource picture than imagining an ordinary deposit of pure osmium blocks.
Osmium is a dense, hard metal, while osmium tetroxide is a volatile, toxic compound with very different behavior. This is a particularly important form distinction. Mechanical wear applications exploit metallic materials; oxidation chemistry uses controlled molecular forms. Neither application should transfer its properties indiscriminately to every osmium-containing substance.
Each section links its supporting references. Descriptions and diagrams were authored for this atlas. Source checks completed. Source checks dated 2026-09-06.
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Family labels and the group-3 layout are teaching conventions. A table position does not establish an unknown bulk property. Electronic configurations refer to neutral atoms; ions and material environments require their own account.
Read each reference property together with its units, conditions and the reference information below.
Not yet recorded: electron affinity, second ionization energy, ground-state term symbol, van der waals radius, thermal conductivity, specific heat capacity, electrical resistivity, crystal structure, lattice parameter a, space group, abundance in seawater, abundance in the universe, annual production, supply-risk listing, hazard classification, biological role, cas registry number, pubchem cid, wikidata item. These families are declared and awaiting an ingestion run against the source each names; they are listed here rather than shown as empty rows.
Physical
Intended reference: CRC Handbook of Chemistry and Physics · CRC Press
Phase at 20 °C
solid
293.15 K, 101.325 kPa
Melting point in K
3306 K
at standard pressure unless noted
Boiling point in K
5285 K
101.325 kPa
Density in g/cm³
22.59 g/cm³
solids and liquids at 293 K; gases at 273 K and 101.325 kPa
Atomic and electronic
Intended reference: Pauling electronegativity scale · Widely tabulated; original in The Nature of the Chemical Bond
Electronegativity in Pauling
2.2 Pauling
Pauling scale
First ionization energy in kJ/mol
840 kJ/mol
gas-phase neutral atom, ground state
Covalent radius in pm
144 pm
single-bond covalent radius
Common oxidation states
+4
states met in ordinary compounds; not exhaustive
Occurrence and identity
Intended reference: CRC Handbook of Chemistry and Physics · CRC Press
Abundance in the crust in mg/kg
0.0015 mg/kg
upper continental crust, mass fraction
Has stable isotopes
Yesderived
Discovery year in CE
1803 CEderived
WHERE IT SITS AMONG ITS NEIGHBORS
Electronegativity across period 6
Os 2.2 Pauling · Osmium
Electronegativity across period 6. Exact values.
Cs
0.79
Ba
0.89
La
1.1
Ce
1.12
Pr
1.13
Nd
1.14
Sm
1.17
Eu
1.2
Gd
1.2
Tb
1.1
Dy
1.22
Ho
1.23
Er
1.24
Tm
1.25
Yb
1.1
Lu
1.27
Hf
1.3
Ta
1.5
W
2.36
Re
1.9
Os
2.2
Ir
2.2
Pt
2.28
Au
2.54
Hg
2
Tl
1.62
Pb
2.33
Bi
2.02
Po
2
At
2.2
Electronegativity down group 8
Os 2.2 Pauling · Osmium
Electronegativity down group 8. Exact values.
Fe
1.83
Ru
2.2
Os
2.2
The trend uses the same reference-property values as the periodic table. Elements with no recorded value are left out of the line rather than drawn at zero.
