sciencefairadventure
44 Ru 101.07(2)

Ruthenium

Transition metal
Symbol Ru
Atomic Number 44
Atomic Weight 101.07(2)
CAS Registry ID 7440-18-8
Group Name Precious metal
Period Number 5
Block d-block
State at STP Solid

Description

Sample of Ruthenium ⌕ Enlarge Image

Ruthenium is a rare transition metal that is a silvery white metal in its natural solid state. This element is known for having ‘hard’ characteristics; it does not tarnish in normal temperatures, but it will yield an explosive effect if it is oxidized. Ruthenium has an atomic weight of 101.07, a melting point of 4233 °F, and a boiling point of 7502 °F. Ruthenium is most commonly used as an addition to other metals such as platinum and titanium to give the metals extra strength.

Isolation

The isolation process of ruthenium is highly complex, and it is not normally conducted in a small laboratory setting.

Ruthenium ⌕ Enlarge Image

Ruthenium is never found free in nature, and it is very rare. Mineral ores which contain elements from the platinum group sometimes contain minute quantities of ruthenium. The ore pentlandite is the ore that is most frequently used for ruthenium isolation. The isolation process of ruthenium is complex due to the many other elements that it is found with; isolating ruthenium out of these other elements involves a number of steps.

The first step to ruthenium isolation is treating the ore with sodium bisulphate and heat; the melted ore contains rhodium sulfate which is insoluble. The liquid ore is then combined with sodium peroxide, and the mixture is then extracted with water to yield the salts of ruthenium and osmium in addition to iron oxide. The salt form of ruthenium is reacted with chlorine gas to yield the highly volatile oxide of ruthenium, RuO4. This oxide is treated with hydrochloric acid; the oxide dissolves in the acid and is precipitated out by treating the solution with ammonium chloride. The precipitate is then subjected to drying and burning under hydrogen gas to yield pure ruthenium metal.

General

NameRuthenium
SymbolRu
Number44
Chemical seriesTransition metal
Group8
Period5
Blockd
Appearancesilvery white metallic
Standard atomic weight101.07(2) g·mol⁻¹
Electron configuration[Kr] 4d7 5s1
Electrons per shell2, 8, 18, 15, 1

Atomic Properties

Crystal structurehexagonal
Oxidation states2, 3, 4, 6, 8 (mildly acidic oxide)
Electronegativity2.2 (scale Pauling)
Ionization energies1st: 710.2 kJ/mol
2nd: 1620 kJ/mol
3rd: 2747 kJ/mol
Atomic radius130 pm
Atomic radius (calc.)178 pm
Covalent radius126 pm
Van der Waals radius

Physical Properties

Phase
Density (near r.t.)12.45  g·cm−3
Liquid density at m.p.10.65  g·cm−3
Melting point2607 K (2334 °C, 4233 °F)
Boiling point4423 K (4150 °C, 7502 °F)
Critical point
Heat of fusion38.59  kJ·mol−1
Heat of vaporization591.6  kJ·mol−1
Heat capacity(25 °C) 24.06  J·mol−1·K−1

Miscellaneous

Magnetic ordering
Electrical resistivity(0 °C) 71 nΩ·m
Thermal conductivity(300 K) 117  W·m−1·K−1
Thermal expansion(25 °C) 6.4  µm·m−1·K−1
Speed of sound (thin rod)(20 °C) 5970 m/s
Young's modulus447  GPa
Shear modulus173  GPa
Bulk modulus220  GPa
Poisson ratio0.30
Mohs hardness6.5
Vickers hardness
Brinell hardness2160  MPa