Ruthenium

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, ruthenium 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. Ruthenium is usually found as a minor component of platinum ores; the annual production has risen from about 19 tonnes in 2009 to some 35.5 tonnes in 2017. Most ruthenium produced is used in wear-resistant electrical contacts and thick-film resistors. A minor application for ruthenium is in platinum alloys and as a chemistry catalyst. A new application of ruthenium is as the capping layer for extreme ultraviolet photomasks. Ruthenium 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.

Ruthenium, ₄₄Ru

Ruthenium
Pronunciation	/ruːˈθiːniəm/ ​(roo-THEE-nee-əm)
Appearance	silvery white metallic
Standard atomic weight Ar°(Ru)
	101.07±0.02 101.07±0.02 (abridged)
Ruthenium in the periodic table
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson Fe ↑ Ru ↓ Os technetium ← ruthenium → rhodium
Atomic number (Z)	44
Group	group 8
Period	period 5
Block	d-block
Electron configuration	[Kr] 4d7 5s1
Electrons per shell	2, 8, 18, 15, 1
Physical properties
Phase at STP	solid
Melting point	2607 K ​(2334 °C, ​4233 °F)
Boiling point	4423 K ​(4150 °C, ​7502 °F)
Density (near r.t.)	12.45 g/cm3
when liquid (at m.p.)	10.65 g/cm3
Heat of fusion	38.59 kJ/mol
Heat of vaporization	619 kJ/mol
Molar heat capacity	24.06 J/(mol·K)
Vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 2588 2811 3087 3424 3845 4388
Atomic properties
Oxidation states	−4, −2, 0, +1, +2, +3, +4, +5, +6, +7, +8 (a mildly acidic oxide)
Electronegativity	Pauling scale: 2.2
Ionization energies	1st: 710.2 kJ/mol 2nd: 1620 kJ/mol 3rd: 2747 kJ/mol
Atomic radius	empirical: 134 pm
Covalent radius	146±7 pm
Spectral lines of ruthenium
Other properties
Natural occurrence	primordial
Crystal structure	​hexagonal close-packed (hcp)
Speed of sound thin rod	5970 m/s (at 20 °C)
Thermal expansion	6.4 µm/(m⋅K) (at 25 °C)
Thermal conductivity	117 W/(m⋅K)
Electrical resistivity	71 nΩ⋅m (at 0 °C)
Magnetic ordering	paramagnetic
Molar magnetic susceptibility	+39×10−6 cm3/mol (298 K)
Young's modulus	447 GPa
Shear modulus	173 GPa
Bulk modulus	220 GPa
Poisson ratio	0.30
Mohs hardness	6.5
Brinell hardness	2160 MPa
CAS Number	7440-18-8
History
Naming	after Ruthenia, the 19th-century Latin name for Russia
Discovery and first isolation	Karl Ernst Claus (1844)
Isotopes of ruthenium v e
Main isotopes Decay abun­dance half-life (t1/2) mode pro­duct 96Ru 5.54% stable 97Ru synth 2.9 d ε 97Tc γ – 98Ru 1.87% stable 99Ru 12.8% stable 100Ru 12.6% stable 101Ru 17.1% stable 102Ru 31.6% stable 103Ru synth 39.26 d β− 103Rh γ – 104Ru 18.6% stable 106Ru synth 373.59 d β− 106Rh
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