Element Osmium

Osmium ElementOsmium (from Greek ὀσμή osme, “smell”) is a chemical element with the symbol Os and atomic number 76.
It is a hard, brittle, bluish-white transition metal in the platinum group that is found as a trace element in alloys, mostly in platinum ores.
Osmium has a blue-gray tint and is the densest stable element; it is approximately twice as dense as lead[3] and slightly denser than iridium. Calculations of density from the X-ray diffraction data may produce the most reliable data for these elements, giving a value of 22.587±0.009 g/cm3 for osmium, slightly denser than the 22.562±0.009 g/cm3 of iridium; both metals are nearly 23 times as dense as water

Names and Identifiers

Chemical Formula:Os
CAS:7440-04-2
Molecular Weight:190.230 g/mol
EC Number :231-114-0
MDL Number:MFCD00011147
Color:bluish gray/ bluish-white
Other Names:Osmio
PubChem CID:22379
IUPAC Name:Osmium
Inchl:InChI=1S/Os
InChI Key:SYQBFIAQOQZEGI-UHFFFAOYSA-N
Canonical SMILES:[Os]
ICSC Number:n/a

Physical & Chemical Properties

Phase:Solid
Density:22.59 g/cm³
Boiling Point:5285 K ​(5012 °C, ​9054 °F)
Melting Point:3306 K ​(3033 °C, ​5491 °F)
Molecular Formula:Os
Flash Point:n/a
Exact Mass:191.961502
Symbol:Globally Harmonized System of ClassificationGlobally Harmonized System of ClassificationGlobally Harmonized System of Classification
Signal Word:Danger
Hazard Statements:H228-H315-H318-H335
Precautionary Statements:P210-P261-P280-P305 + P351 + P338
Hazard Codes:F,Xi
Risk Phrases:11-37/38-41-36/38
Safety Phrases:S16-S26-S36/37/39
RIDADR:UN 3089 4.1/PG 2
WGK Germany:n/a
RTECS:RN1100000
Packaging Group:II
Hazard Class:4.1

Osmium has seven naturally occurring isotopes, six of which are stable: 184Os, 187Os, 188Os, 189Os, 190Os, and (most abundant) 192Os. 186 Os undergoes alpha decay with such a long half-life (2.0±1.1)×1015 years, approximately 140000 times the age of the universe, that for practical purposes it can be considered stable.

Naturally occurring isotopes

IsotopeMass/DaNatural abundance (atom %)Nuclear spin (I)Magnetic moment (μ/μN)
184Os183.952488 (4)0.02 (1)0
186Os185.953830 (4)1.59 (3)0
187Os186.955741 (3)1.96 (2)1/20.06465185
188Os187.955830 (3)13.24 (8)0
189Os188.958137 (4)16.15 (5)3/20.659933
190Os189.958436 (4)26.26 (2)0
192Os191.961467 (4)40.78 (19)0

Radiosotope data

IsotopeMass/DaHalf-lifeMode of decayNuclear spinNuclear magnetic moment
182Os181.9521921.5 hEC to 182Re0
183Os182.953113 hEC to 183Re9/2
185Os184.95404393.6 dEC to 185Re1/2
191Os190.96092815.4 dβ to 191Ir9/2
193Os192.96413830.5 hβ to 193Ir3/20.73
194Os193.9651796.0 yβ to 194Ir0

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