Osmium

76
Os
Group
8
Period
6
Block
d
Protons
Electrons
Neutrons
76
76
114
General Properties
Atomic Number
76
Atomic Weight
190.23
Mass Number
190
Category
Transition metals
Colour
Slate Gray
Radioactive
No
From the Greek word osme, meaning smell
Crystal Structure
Simple Hexagonal
History
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.
Electrons per shell
2, 8, 18, 32, 14, 2
Electron Configuration
[Xe] 4f14 5d6 6s2
Os
Osmium is the least abundant stable element in the Earth's crust
Physical Properties
Phase
Solid
Density
22.61 g/cm3
Melting Point
3306.15 K | 3033 °C | 5491.4 °F
Boiling Point
5285.15 K | 5012 °C | 9053.6 °F
Heat of Fusion
31 kJ/mol
Heat of Vaporization
630 kJ/mol
Specific Heat Capacity
0.13 J/g·K
Abundance in Earth's crust
1.8×10-7%
Abundance in Universe
3×10-7%
Osmium
Image Credits: Wikimedia Commons (Alchemist-hp)
Osmium crystals produced by chemical transport reaction in chlorine gas
CAS Number
7440-04-2
PubChem CID Number
23937
Atomic Properties
Atomic Radius
135 pm
Covalent Radius
144 pm
Electronegativity
2.2 (Pauling scale)
Ionization Potential
8.4382 eV
Atomic Volume
8.49 cm3/mol
Thermal Conductivity
0.876 W/cm·K
Oxidation States
-2, 1, 2, 3, 4, 5, 6, 7, 8
Applications
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.
Even low concentrations in air can cause lung congestion, skin damage, or eye damage
Isotopes
Stable Isotopes
184Os, 187Os, 188Os, 189Os, 190Os, 192Os
Unstable Isotopes
161Os, 162Os, 163Os, 164Os, 165Os, 166Os, 167Os, 168Os, 169Os, 170Os, 171Os, 172Os, 173Os, 174Os, 175Os, 176Os, 177Os, 178Os, 179Os, 180Os, 181Os, 182Os, 183Os, 185Os, 186Os, 191Os, 193Os, 194Os, 195Os, 196Os