|
Symbol
|
Ru
|
|
Atomic number |
44 |
|
Atomic mass |
101.1 g.mol -1 |
|
Electronegativity
according to Pauling |
2.2 |
|
Density |
12.2 g.cm-3 at 20°C |
|
Melting point |
2250 °C |
|
Boiling point |
4150 °C |
|
Vanderwaals radius |
0.135 nm |
|
Isotopes |
11 |
|
Electronic shell |
[ Kr ] 4d7 5s1 |
|
Energy of first
ionisation |
722.4 kJ.mol -1 |
| Energy of second ionisation |
1620 kJ.mol -1 |
| Energy of third ionisation |
2747 kJ.mol -1 |
|
Standard Potential |
0.45 V |
Ruthenium
Ruthenium, together with rhodium,
palladium, osmium, iridium, and
platinum form a group of elements referred to as the platinum group metals
(PGM).
Ruthenium is a
hard, white metal. It does not tarnish at room temperatures, but
oxidises in air at about 800°C. The metal is not attacked by hot or
cold acids or aqua regia, but when potassium chlorate is added to the
solution, it oxidises explosively.
It dissolved in molten alkalis.
Applications
Ruthenium demand is rising: the metal find use in the electronic
industry (50%) and the chemical industry (40%), with smaller amounts
being used in alloying. In electronics it used to be used mainly for
electrical contacts but most now goes into chip resistors. In the
chemical industry it is used in the anodes for chlorine production in
electrochemical cells.
The metal is used as a hardener for palladium
and platinum and added in small amounts improves
the corrosion resistance of titaniumin. It is
used in electrical contact alloys and filaments, in jewelry, in pen
nibs, and in instrument pivots. It is also used in alloys with
cobalt, molybdenum,
nickel, tungsten, and
other metals. Ruthenium compounds are used to color ceramics and glass.
Ruthenium is also a versatile catalyst, used for instance in the removal
of H2S from oil refineries and from other industrial
processes, for the production of ammonia from natural gas, and for the
production of acetic acid from methanol.
Some ruthenium complexes absorb light throughout the visible spectrum
and are being actively researched in various, potential, solar energy
technologies.
Ruthenium in the environment
Ruthenium is one of the rarest metals on Earth.
Ruthenium is found as the free
metal, sometimes associated with platinum, osmium and
iridium, in North
and South America, and in South Africa. There are few minerals, such as
laurite, ruarsite and ruthenarsenite. All are rare and none acts as a
commercial source of the metal. Ruthenium is
also associated with nickel and deposits (from which it is recovered
commercially).
World production is 12 tonnes per year and reserves are hestimated to be
ariund 5.000 tonnes.
Back to
the periodic table of elements
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