PTL:Ruthenium

From ChemEd Collaborative

Ruthenium is a transition metal in the iron subgroup of Group VIIIB (Group 8) and the 5th period. Other elements in the group are iron (Fe) and osmium (Os). It is one of the six platinum group elements: ruthenium (Ru), osmium (Os), rhodium (Rh), iridium (Ir), palladium (Pd), and platinum (Pt).

1 Discovered
2 Name
3 Characteristics
4 Reactions
5 Uses
6 Emission Spectra

Discovered

Like osmium, rhodium, and iridium, ruthenium was discovered in the residue left after dissolving crude platinum in aqua regia. Although the element was apparently first discovered in 1807 by the Polish chemist J. Sniadecki, the credit is generally given to K. Klaus (1844) who

Name

named the element after Ruthenia, the Latin name for Russia and the source of the platinum ores used in his work.

Characteristics

Ruthenium is exceedingly rare in the earth's crust (0.0001 ppm), some 50 times less abundant than its neighbor osmium. (Note the contrast between these abundances and that of iron, the other member of this subgroup.) As a consequence, Ru is an expensive element, costing about $1400 per 100 grams (in 1991), although not nearly as expensive as the other platinum group elements (except for Pd, which costs less than Ru). Like osmium, rhodium, and iridium, ruthenium is a by-product of the nickel processing industry.

Ru has oxidation numbers ranging from 0 to 8 in its compounds, but +2, +3, and +4 are most common.

Reactions

The metal is white and extremely hard. It does not tarnish in air, but it is attacked at temperatures higher than 800°C. It does not react with hot or cold acids or with aqua regia. In contrast, it is attacked by halogens and hydroxides.

Uses

Ruthenium is used in many alloys used in everyday objects such as telephone relay switches and fountain pens (above)

Ruthenium is a very effective hardener in alloys with Pt and Pd and so is used to make [electrical contacts] that have high wear resistance. Ruthenium alloys are used in [fountain pen] points. When only a trace is added to titanium, the corrosion resistance of the titanium is increased 100-fold. Finally, ruthenium compounds are very effective catalysts.