Ruthenium, Ru

Ruthenium is a chemical element that has the symbol Ru and atomic number 44. A rare transition metal of the platinum group of the periodic table, ruthenium is found associated with platinum ores and used as a catalyst in some platinum alloys.

A polyvalent hard white metal, ruthenium is a member of the platinum group, has four crystal modifications and does not tarnish at normal temperatures, but does oxidize readily on exposure to air to form ruthenium tetroxide, RuO4, a strong oxidising agent with properties analogous to those of osmium tetroxide. Ruthenium dissolves in fused alkalis, is not attacked by acids but is attacked by halogens at high temperatures. 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 ruthenium.

This metal can be plated either through electrodeposition or by thermal decomposition methods. One ruthenium-molybdenum alloy has been found to be superconductive at 10.6 K. The oxidation states of ruthenium range from +1 to +8, and -2 is known, though oxidation states of +2, +3, and +4 are most common.

Technical Data
Symbol Ru Density (20°C)/gcm3 12.41
Atomic number 44 Melting point / °C 2282(+/-20)
No. of naturally occurring isotopes 7 Boiling point / °C 4050(+/-100)
Atomic weight 101.07(+/-3) ΔHfus/kJmol-1 -25.5
Electronic configuration [Kr]4d75s1 ΔHvap/kJmol-1 -
Metal radius(12-coordinate)/pm 134 ΔHf(monoatomic gas)/kJmol-1 640
Ionic radius(4-coordinate)/pm VIII 36 Electrical resistivity  
Ionic radius(4-coordinate)/pm VII 38 (20°C)/μohm cm 6.71
Ionic radius(6-coordinate)/pm V 56.5 Ionization energy/kJmol-1 I 711
Ionic radius(6-coordinate)/pm IV 62 Ionization energy/kJmol-1 II 1617
Ionic radius(6-coordinate)/pm III 68 Ionization energy/kJmol-1 III 2747
Evaporation Techniques
Temperature (oC) @Vap. Pressure Techniques Remarks
10-8 Torr 10-6 Torr 10-4 Torr Electron Beam Crucible Coil Boat
1780 1990 2260 Poor - - Tungsten Spits violently in EB, requires degas.

Evaporation Materials
R4-5000-M pieces 1-4mm
R4-10000-P -20 mesh
R4-10001-P -325 mesh
R4-10004-P -200 mesh
R4-2000-R 0.0625" (1.58mm)
R4-2001-R 0.125" (3.175mm)
R4-2002-R 0.250" (6.35mm)
R4-2003-R 0.500" (12.7mm)