Ruthenium is a chemical element with the symbol Ru and atomic number 44. It is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, Ru is inert to most other chemicals. Russian-born scientist of Baltic-German ancestry Karl Ernst Claus discovered the element in 1844 at Kazan State University and named ruthenium in honor of Russia, Ruthenia is the Latin name of Rus.
Most ruthenium produced is used in wear-resistant electrical contacts and thick-film resistors. A minor application for Ru is in platinum alloys and as a chemistry catalyst. A new application of ruthenium is as the capping layer for extreme ultraviolet photo-masks. It is generally found in ores with the other platinum group metals in the Ural Mountains and in North and South America. Small but commercially important quantities are also found in pentlandite extracted from Sudbury, Ontario and in pyroxenite deposits in South Africa.
Characteristics of Ru
- It is a polyvalent hard white metal, is a member of the platinum group and is in group 8 of the periodic table.
- It has four crystal modifications and does not tarnish at ambient conditions; it oxidizes upon heating to 800 °C.
- It is dissolves in fused alkalis to give ruthenates (RuO2−4), is not attacked by acids but is attacked by halogens at high temperatures.
- Ru is most readily attacked by oxidizing agents. Small amounts of ruthenium can increase the hardness of platinum and palladium. The corrosion resistance of titanium is increased markedly by the addition of a small amount of Ru.
- The metal can be plated by electroplating and by thermal decomposition. A ruthenium-molybdenum alloy is known to be superconductive at temperatures below 10.6 K.
- Ru is the last of the 4d transition metals that can assume the group oxidation state +8, and even then it is less stable there than the heavier congener osmium.
- It is the first group from the left of the table where the second and third-row transition metals display notable differences in chemical behavior.