Osmium

Osmium (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.

What the numbers say

At standard temperature and pressure Osmium is a solid, sitting in period 6, group 8 of the d-block.

Its melting point of 3306 K (3033 °C) is the 4th highest of the 110 elements with a measured value — one of the most refractory elements there is.

At 22.59 g/cm³ it is the 1st densest of 96 elements with a quoted density.

Pauling electronegativity is 2.2. Paired with oxygen (3.44) that is a difference of 1.24, which puts the bond polar covalent — oxides here tend to be semiconducting or refractory rather than salt-like.

In the solid state it takes a simple hexagonal structure — hexagonal packing offers few easy slip systems, so properties are anisotropic and formability is limited.

It is reported in 9 oxidation states (-2, 1, 2, 3, 4, 5, 6, 7, 8), which sets how many distinct compounds and phases it can form.

First identified in 1803.

Crystal structure

Check it against computed structures

The structure search queries the Materials Project, OQMD and the Open Materials Database for computed crystal structures containing Os — with DFT formation energy, hull stability and band gap where the provider publishes them.