An Overview about the Chemical Element Ruthenium

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Symbol: Ru

Atomic Number: 44

Atomic Mass: 101.07 amu (atomic mass units)

Melting Point: 2250.0 C (2523.15 K, 4082.0 F)

Boiling Point: 3900.0 C (4173.15 K, 7052.0 F)

Number of Protons: 44

Number of Electrons: 44

Number of Neutrons: 57

Classification: Transition Metal

Group name: Platinum Group Metal (PGM) or Precious Metal

Crystal Structure: Hexagonal

Density @ 293 K: 12.2 grams per cubic centimeter

Color: silver

The first person to believe he had discovered ruthenium was a Polish chemist called Jedrzej Sniadecki. In 1807 he isolated what he thought to be a new element from platinum ore. He called his new element vestium. As his claim was not ratified he withdrew it.

In 1828 Gottfried Wilhelm Osann, a German chemist, was working with the Swedish chemist Jons Jacob Berzelius. Working on the residue left after dissolving platinum ore in aqua regia Osann believed he found three new metals which he named ruthenium, polinium and pluranium. Berzelius was unable to confirm this.

The man eventually credited with the discovery of ruthenium is the Russian chemist Karl Karlovich Klaus who produced about six grams of ruthenium from platinum ore in 1844. The name of the element comes from the Latin word for Russia "Ruthenia".

Along with platinum, palladium, osmium, rhodium, and iridium, ruthenium is a member of the Platinum Group Metals (PGM). The silver-white element is a hard metal which has four different crystal modifications. While the metal will not tarnish at room temperatures it will oxidize at temperatures in excess of 800 C (1073 K, 1472 F). The metal is not attacked by either dilute or concentrated acids or by aqua regia. Potassium chlorate can induce an explosive oxidation of ruthenium.

Natural ruthenium is made up of seven stable isotopes. The most common isotope is ruthenium-102 at 31.55%. The other isotopes in order of abundance are ruthenium-104 (18.62%), ruthenium-101 (17.66%), ruthenium-99 (12.76%), ruthenium-100 (12.60%), ruthenium-96 (5.54%) and ruthenium-98 (1.87%). There are a number of unstable isotopes of ruthenium with mass numbers ranging from 87 to 120.

Ruthenium is extracted from platinum ores. It is also a commercial by product from the Nickel mining of Sudbury, Ontario, Canada and the pyroxinite deposits found in South .Africa. Mainly used as an alloy it has a number of applications.

* Alloyed to platinum or palladium it increases hardness making the resistant to wear. Such alloys are used to make electrical contacts.

* As little as 0.1% ruthenium alloyed to titanium will increase titanium's corrosion resistance 100 times.

* Ruthenium-molybdenum alloy is a super-conductor at temperatures lower than minus 262.55 C (10.6 K, minus 440.59 F).

* Ruthenium is being used to make a number of medically therapeutic drugs. These drugs include antimalarials, antibiotics, immunosuppressives and cancer therapies.

A possible use that is being worked on is as a catalyst to break down hydrogen sulfide in the petroleum refining and other chemical industries. An aqueous suspension of cadmium sulfide particle which has been loaded with ruthenium oxide will split hydrogen sulfide with the aid of light.

Los Alamos National Laboratory Chemistry Division

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