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About Osmium

Osmium Bohr

Osmium was first isolated in the form of osmium tetroxide, OsO4, and was in fact named from the Greek osme, meaning “a smell”, due to the intense odor of this compound. This compound forms spontaneously when pure osmium metal is in contact with air, and is both volatile and extremely toxic, and thus the pure metal is rarely used. Osmium is, however, the densest naturally occurring element and imparts hardness when used in metal alloys. Hard osmium-containing alloys are used in many contexts where resistance to wear due to friction or frequent operation is desirable; this includes use in the tips of fountain pens, instrument pivots, and electrical contacts.

Despite its extreme toxicity, osmium tetroxide is the most frequently used osmium compound. It is valuable in the life sciences for staining and fixing biological tissue for electron microscopy, where it provides contrast that would otherwise be lacking when imaging substances made primarily of carbon. Additionally, it is used as a lipid stain in light microscopy and in some cases for fingerprint detection. Osmium tetroxide is also valued as a chemical catalyst in Sharpless asymmetric dihydroxylation, a reaction for which Karl Barry Sharpless won the Nobel Prize in Chemistry in 2001. The expense of the compound limits its use for this purpose to some degree, but it is considered a far superior catalyst for this process compared to the alternative, KMnO4. Finally, organometallic complexes containing osmium are under investigation for potential use in cancer treatment.

Like other platinum group metals, osmium is typically obtained for commercial use as a byproduct of nickel and copper mining and processing, but can also be obtained from ores rich in platinum and from alluvial deposits.


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High Purity (99.999%) Osmium Oxide (OsO) Powder Osmium is the densest naturally occurring element and metal, and is almost entirely used to produce very hard alloys with other metals of the platinum group. Osmium tetroxide has recently been used to detect fingerprints and as an aid to stain biological samples in preparation for microscopy studies. Osmium is available as metal and compounds with purities from 99% to 99.999% (ACS grade to ultra-high purity). High Purity (99.999%) Osmium (Os) Sputtering TargetElemental or metallic forms include pellets, rod, wire and granules for evaporation source material purposes. Osmium nanoparticles and nanopowders are also available. Oxides are available in powder and dense pellet form for such uses as optical coating and thin film applications. Oxides tend to be insoluble. Fluorides are another insoluble form for uses in which oxygen is undesirable such as metallurgy, chemical and physical vapor deposition and in some optical coatings. Osmium is also available in soluble forms including chlorides, nitrates and acetates. These compounds can be manufactured as solutions at specified stoichiometries.

Osmium Properties

Osmium(Os) atomic and molecular weight, atomic number and elemental symbolOsmium is a Block D, Group 8, Period 6 element. The number of electrons in each of osmium's shells is 2, 8, 18, 32, 14, 2 and its electron configuration is [Xe] 4f14 5d6 6s2. Elemental OsmiumThe osmium atom has a radius of and its Van der Waals radius is In its elemental form, CAS 7440-04-2, Osmium has a silvery blue cast apperance. Osmium has the highest melting point and the lowest vapor pressure of any of the platinum group of metals. Osmium Bohr ModelOsmium is the least abundant stable element in the earth's crust and is the densest stable element. It is found in the alloys osmiridium and iridiosmium and as an uncombined element. Osmium was first discovered by Smithson Tennant in 1803. The origin of the name Osmium comes from the Greek word osme meaning a smell or odor.

Symbol: Os
Atomic Number: 76
Atomic Weight: 190.23
Element Category: transition metal
Group, Period, Block: 8, 6, d
Color: bluish gray/ bluish-white
Other Names: Osmio
Melting Point: 3033 °C, 5491 °F, 3306 K
Boiling Point: 5012 °C, 9054 °F, 5285 K
Density: 22.59 g·cm3
Liquid Density @ Melting Point: 20 g·cm3
Density @ 20°C: 22.61 g/cm3
Density of Solid: 22610 kg·m3
Specific Heat: 0.13 (kJ/kg K)
Superconductivity Temperature: 0.66 [or -272.49 °C (-458.48 °F)] K
Triple Point: N/A
Critical Point: N/A
Heat of Fusion (kJ·mol-1): 29.3
Heat of Vaporization (kJ·mol-1): 738.06
Heat of Atomization (kJ·mol-1): 791
Thermal Conductivity: 87.6 W·m-1·K-1
Thermal Expansion: (25 °C) 5.1 µm·m-1·K-1
Electrical Resistivity: (0 °C) 81.2 nΩ·m
Tensile Strength: N/A
Molar Heat Capacity: 24.7 J·mol-1·K-1
Young's Modulus: N/A
Shear Modulus: 222 GPa
Bulk Modulus: 462 GPa
Poisson Ratio: 0.25
Mohs Hardness: 7
Vickers Hardness: 3920 MPa
Brinell Hardness: N/A
Speed of Sound: (20 °C) 4940 m·s-1
Pauling Electronegativity: 2.2
Sanderson Electronegativity: N/A
Allred Rochow Electronegativity: 1.52
Mulliken-Jaffe Electronegativity: N/A
Allen Electronegativity: N/A
Pauling Electropositivity: 1.8
Reflectivity (%): N/A
Refractive Index: N/A
Electrons: 76
Protons: 76
Neutrons: 114
Electron Configuration: [Xe] 4f14 5d6 6s2
Atomic Radius: 135 pm
Atomic Radius,
non-bonded (Å):
Covalent Radius: 144±4 pm
Covalent Radius (Å): 1.36
Van der Waals Radius: 216 pm
Oxidation States: 8, 7, 6, 5, 4, 3, 2, 1, 0, -1, -2 (mildly acidic oxide)
Phase: Solid
Crystal Structure: hexagonal close-packed
Magnetic Ordering: paramagnetic
Electron Affinity (kJ·mol-1) 106.096
1st Ionization Energy: 840 kJ·mol-1
2nd Ionization Energy: 1600 kJ·mol-1
3rd Ionization Energy: N/A
CAS Number: 7440-04-2
EC Number: 231-114-0
MDL Number: MFCD00011147
Beilstein Number: N/A
SMILES Identifier: [Os]
InChI Identifier: InChI=1S/Os
PubChem CID: 22379
ChemSpider ID: 23937
Earth - Total: 880 ppb
Mercury - Total: 670 ppb
Venus - Total: 920 ppb
Earth - Seawater (Oceans), ppb by weight: N/A
Earth - Seawater (Oceans), ppb by atoms: N/A
Earth -  Crust (Crustal Rocks), ppb by weight: 1.8
Earth -  Crust (Crustal Rocks), ppb by atoms: 0.2
Sun - Total, ppb by weight: 2
Sun - Total, ppb by atoms: 0.02
Stream, ppb by weight: N/A
Stream, ppb by atoms: N/A
Meterorite (Carbonaceous), ppb by weight: 670
Meterorite (Carbonaceous), ppb by atoms: 70
Typical Human Body, ppb by weight: N/A
Typical Human Body, ppb by atom: N/A
Universe, ppb by weight: 3
Universe, ppb by atom: 0.02
Discovered By: Smithson Tennant
Discovery Date: 1803
First Isolation: Smithson Tennant (1803)

Health, Safety & Transportation Information for Osmium

Osmium is extremely volatile and toxic in its oxide state. Safety data for Osmium and its compounds can vary widely depending on the form. For potential hazard information, toxicity, and road, sea and air transportation limitations, such as DOT Hazard Class, DOT Number, EU Number, NFPA Health rating and RTECS Class, please see the specific material or compound referenced in the Products tab. The below information applies to elemental (metallic) Osmium.

Safety Data
Signal Word Danger
Hazard Statements H228-H315-H318-H335
Hazard Codes F, Xi
Risk Codes 11-37/38-41
Safety Precautions 16-26-36/37/39
RTECS Number RN1100000
Transport Information UN 3089 4.1/PG 2
WGK Germany nwg
Globally Harmonized System of
Classification and Labelling (GHS)
Exclamation Mark-Acute Toxicity Corrosion-Corrosive to metals Flame-Flammables
Review and Print SDS for Osmium Metal


Date Created: 05/15/2015
Date Revised: 05/15/2015


Product Name: Osmium Metal

Product Number: All applicable American Elements product codes, e.g. OS-M-02, OS-M-03, OS-M-04, OS-M-05

CAS #: 7440-04-2

Relevant identified uses of the substance: Scientific research and development

Supplier details:
American Elements
1093 Broxton Ave. Suite 2000
Los Angeles, CA 90024
Tel: +1 310-208-0551
Fax: +1 310-208-0351

Emergency telephone number:
Domestic, North America +1 800-424-9300
International +1 703-527-3887


Classification of the substance or mixture
Classification according to Directive 67/548/EEC or Directive 1999/45/EC
Information concerning particular hazards for human and environment: Not applicable
Label elements
Labelling according to EU guidelines:
Code letter and hazard designation of product:
Risk phrases:
Hazard description:
WHMIS classification
Classification system
HMIS ratings (scale 0-4)
(Hazardous Materials Identification System)
Health (acute effects) = 0
Flammability = 0
Reactivity = 0
Other hazards
Results of PBT and vPvB assessment
PBT: Not applicable.
vPvB: Not applicable.


Chemical characterization: Substances
CAS# Description:
7440-04-2 Osmium
Identification number(s):
EC number: 231-114-0


Description of first aid measures
After inhalation
Supply fresh air. If required, provide artificial respiration. Keep patient warm.
Seek immediate medical advice.
After skin contact
Immediately wash with water and soap and rinse thoroughly.
Seek immediate medical advice.
After eye contact
Rinse opened eye for several minutes under running water. Then consult a doctor.
After swallowing Seek medical treatment.
Information for doctor
Most important symptoms and effects, both acute and delayed
No further relevant information available.
Indication of any immediate medical attention and special treatment needed
No further relevant information available.


Extinguishing media
Suitable extinguishing agents Special powder for metal fires. Do not use water.
For safety reasons unsuitable extinguishing agents Water
Special hazards arising from the substance or mixture
In case of fire, the following can be released:
Toxic metal oxide fume
Advice for firefighters
Protective equipment:
Wear self-contained respirator.
Wear fully protective impervious suit.


Personal precautions, protective equipment and emergency procedures
Wear protective equipment. Keep unprotected persons away.
Ensure adequate ventilation
Keep away from ignition sources
Environmental precautions:
Do not allow material to be released to the environment without proper governmental permits.
Methods and material for containment and cleaning up:
Ensure adequate ventilation.
Keep away from ignition sources.
Reference to other sections
See Section 7 for information on safe handling
See Section 8 for information on personal protection equipment.
See Section 13 for disposal information.


Precautions for safe handling
Handle under dry protective gas.
Keep container tightly sealed.
Store in cool, dry place in tightly closed containers.
Ensure good ventilation at the workplace.
Information about protection against explosions and fires:
Protect against electrostatic charges.
Conditions for safe storage, including any incompatibilities
Requirements to be met by storerooms and receptacles: Store in a cool location.
Information about storage in one common storage facility:
Store away from oxidizing agents.
Store away from halogens.
Do not store with interhalogens.
Store away from phosphorus.
Store away from air.
Further information about storage conditions:
Store under dry inert gas.
Keep container tightly sealed.
Store in cool, dry conditions in well sealed containers.
This product is air sensitive.
Specific end use(s) No further relevant information available.


Additional information about design of technical systems:
Properly operating chemical fume hood designed for hazardous chemicals and having an average
face velocity of at least 100 feet per minute.
Control parameters
Components with limit values that require monitoring at the workplace:
Additional information: No data
Exposure controls
Personal protective equipment
General protective and hygienic measures
The usual precautionary measures for handling chemicals should be followed.
Keep away from foodstuffs, beverages and feed.
Remove all soiled and contaminated clothing immediately.
Wash hands before breaks and at the end of work.
Maintain an ergonomically appropriate working environment.
Breathing equipment: Use suitable respirator when high concentrations are present.
Protection of hands:
Impervious gloves
Check protective gloves prior to each use for their proper condition.
Material of gloves
The selection of suitable gloves not only depends on the material, but also on quality.
Quality will vary from manufacturer to manufacturer.
Eye protection: Safety glasses
Body protection: Protective work clothing.


Information on basic physical and chemical properties
General Information
Form: Disc/Target
Color: grey
pH-value: Not applicable.
Change in condition
Melting point/Melting range: 3045°C (5513 °F)
Boiling point/Boiling range: 5027°C (9081 °F)
Sublimation temperature / start: Not determined
Flammability (solid, gaseous) Highly flammable.
Ignition temperature: Not determined
Decomposition temperature: Not determined
Auto igniting: Not determined.
Explosion limits:
Lower: Not determined
Upper: Not determined
Vapor pressure at 2450°C (4442 °F): 0.0013 hPa
Density at 20°C (68 °F): 22.61 g/cm³ (188.68 lbs/gal)
Relative density Not determined.
Vapour density Not applicable.
Evaporation rate Not applicable.
Solubility in / Miscibility with
Water: Insoluble
Segregation coefficient (n-octonol/water): Not determined.
dynamic: Not applicable.
kinematic: Not applicable.
Other information No further relevant information available.


Chemical stability
Thermal decomposition / conditions to be avoided:
Decomposition will not occur if used and stored according to specifications.
Possibility of hazardous reactions
Osmium powder forms toxic osmium tetroxide when exposed to air.
Incompatible materials:
Oxidizing agents
Hazardous decomposition products: Toxic metal oxide fume


Information on toxicological effects
Acute toxicity:
Primary irritant effect:
on the skin: May cause irritation
on the eye: May cause irritation
Sensitization: No sensitizing effects known.
Additional toxicological information:
To the best of our knowledge the acute and chronic toxicity of this substance is not fully known.
No classification data on carcinogenic properties of this material is available from the EPA, IARC, NTP, OSHA or ACGIH.
The Registry of Toxic Effects of Chemical Substances (RTECS) contains acute and/or other multiple dose toxicity data for components in this product.


Aquatic toxicity: No further relevant information available.
Persistence and degradability No further relevant information available.
Behavior in environmental systems:
Bioaccumulative potential No further relevant information available.
Mobility in soil No further relevant information available.
Additional ecological information:
General notes:
Do not allow material to be released to the environment without proper governmental permits.
Results of PBT and vPvB assessment
PBT: Not applicable.
vPvB: Not applicable.
Other adverse effects No further relevant information available.


Waste treatment methods
Recommendation Consult state, local or national regulations to ensure proper disposal.
Uncleaned packagings:
Recommendation: Disposal must be made according to official regulations.


DOT, ADR, ADN, IMDG, IATA Not applicable
UN proper shipping name
DOT, ADR, ADN, IMDG, IATA Not applicable
Transport hazard class(es)
Class Not applicable
Packing group
DOT, ADR, IMDG, IATA Not applicable
Environmental hazards:
Marine pollutant: Yes (PP)
Special precautions for user Not applicable.
Transport in bulk according to Annex II of
MARPOL73/78 and the IBC Code Not applicable.


Safety, health and environmental regulations/legislation specific for the substance or mixture
Product related hazard informations:
Hazard symbols:
F Highly flammable
Risk phrases:
11 Highly flammable.
National regulations
All components of this product are listed in the U.S. Environmental Protection Agency Toxic Substances Control Act Chemical substance Inventory.
All components of this product are listed on the Canadian Domestic Substances List (DSL).
Information about limitation of use: For use only by technically qualified individuals.
Other regulations, limitations and prohibitive regulations
REACH - Pre-registered substances Substance is listed.
Chemical safety assessment: A Chemical Safety Assessment has not been carried out.


Safety Data Sheet according to Regulation (EC) No. 1907/2006 (REACH). The above information is believed to be correct but does not purport to be all inclusive and shall be used only as a guide. The information in this document is based on the present state of our knowledge and is applicable to the product with regard to appropriate safety precautions. It does not represent any guarantee of the properties of the product. American Elements shall not be held liable for any damage resulting from handling or from contact with the above product. See reverse side of invoice or packing slip for additional terms and conditions of sale. COPYRIGHT 1997-2016 AMERICAN ELEMENTS. LICENSED GRANTED TO MAKE UNLIMITED PAPER COPIES FOR INTERNAL USE ONLY.

Osmium Isotopes

Osmium (Os) has seven naturally occurring isotopes. Six of them are stable: 184Os, 187Os, 188Os, 189Os, 190Os, and (most abundant) 192Os. One of them, 186Os, has an extremely long half-life (2×1015 years)

Nuclide Isotopic Mass Half-Life Mode of Decay Nuclear Spin Magnetic Moment Binding Energy (MeV) Natural Abundance
(% by atom)
162Os 161.98443(54)# 1.87(18) ms a to 158W 0+ N/A 1242.11 -
163Os 162.98269(43)# 5.5(6) ms a to 159W; ß+ + p to 162W; ß+ to 163Re 7/2-# N/A 1250.19 -
164Os 163.97804(22) 21(1) ms a to 160W; ß+ to 164Re 0+ N/A 1267.58 -
165Os 164.97676(22)# 71(3) ms a to 161W; ß+ to 165Re (7/2-) N/A 1275.66 -
166Os 165.972691(20) 216(9) ms a to 162W; ß+ to 166Re 0+ N/A 1283.74 -
167Os 166.97155(8) 810(60) ms a to 163W; ß+ to 167Re 3/2-# N/A 1291.82 -
168Os 167.967804(13) 2.06(6) s ß+ to 168Re; a to 164W 0+ N/A 1309.21 -
169Os 168.967019(27) 3.40(9) s ß+ to 169Re; a to 165W 3/2-# N/A 1317.29 -
170Os 169.963577(12) 7.46(23) s ß+ to 170Re; a to 166W 0+ N/A 1325.37 -
171Os 170.963185(20) 8.3(2) s ß+ to 171Re; a to 167W (5/2-) N/A 1333.45 -
172Os 171.960023(16) 19.2(5) s ß+ to 172Re; a to 168W 0+ N/A 1341.53 -
173Os 172.959808(16) 22.4(9) s ß+ to 173Re; a to 169W (5/2-) N/A 1358.92 -
174Os 173.957062(12) 44(4) s ß+ to 174Re; a to 170W 0+ N/A 1367 -
175Os 174.956946(15) 1.4(1) min ß+ to 175Re (5/2-) N/A 1375.08 -
176Os 175.95481(3) 3.6(5) min ß+ to 176Re 0+ N/A 1383.16 -
177Os 176.954965(17) 3.0(2) min ß+ to 177Re 1/2- N/A 1391.24 -
178Os 177.953251(18) 5.0(4) min ß+ to 178Re 0+ N/A 1399.31 -
179Os 178.953816(19) 6.5(3) min ß+ to 179Re (1/2-) N/A 1407.39 -
180Os 179.952379(22) 21.5(4) min ß+ to 180Re 0+ N/A 1415.47 -
181Os 180.95324(3) 105(3) min ß+ to 181Re 1/2- N/A 1423.55 -
182Os 181.952110(23) 22.10(25) h EC to 182Re 0+ N/A 1431.63 -
183Os 182.95313(5) 13.0(5) h EC to 183Re 9/2+ N/A 1439.71 -
184Os 183.9524891(14) Observationally Stable - 0+ N/A 1447.79 0.02
185Os 184.9540423(14) 93.6(5) d EC to 185Re 1/2- N/A 1455.87 -
186Os 185.9538382(15) 2.0(11)E+15 y - 0+ N/A 1463.94 1.59
187Os 186.9557505(15) Observationally Stable - 1/2- 0.06465185 1472.02 1.96
188Os 187.9558382(15) Observationally Stable - 0+ N/A 1480.1 13.24
189Os 188.9581475(16) Observationally Stable - 3/2- 0.659933 1488.18 16.15
190Os 189.9584470(16) Observationally Stable - 0+ N/A 1496.26 26.26
191Os 190.9609297(16) 15.4(1) d ß- to 191Ir 9/2- N/A 1495.02 -
192Os 191.9614807(27) Observationally Stable - 0+ N/A 1503.1 40.78
193Os 192.9641516(27) 30.11(1) h ß- to 193Ir 3/2- 0.73 1511.18 -
194Os 193.9651821(28) 6.0(2) y ß- to 194Ir 0+ N/A 1519.26 -
195Os 194.96813(54) 6.5 min ß- to 195Ir 3/2-# N/A 1527.34 -
196Os 195.96964(4) 34.9(2) min ß- to 196Ir 0+ N/A 1535.41 -
197Os 197 2.8(6) min Unknown N/A N/A N/A -