Rhodium

Rhodium is a chemical element with the symbol Rh and atomic number 45. It is an extraordinarily rare, silvery-white, hard, corrosion-resistant, and chemically inert transition metal.

What the numbers say

At standard temperature and pressure Rhodium is a solid, sitting in period 5, group 9 of the d-block.

Its melting point of 2237 K (1964 °C) is the 14th highest of the 110 elements with a measured value — mid-range among the elements.

At 12.45 g/cm³ it is the 18th densest of 96 elements with a quoted density.

Pauling electronegativity is 2.28. Paired with oxygen (3.44) that is a difference of 1.16, 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 face-centered cubic structure — FCC packing gives 12 independent slip systems, which is why FCC metals are the ductile, formable ones.

It is reported in 7 oxidation states (-1, 1, 2, 3, 4, 5, 6), 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 Rh — with DFT formation energy, hull stability and band gap where the provider publishes them.