Rhodium

Rhodium (Rh)

Silvery white metallic transition element. Found with platinum and used in some platinum alloys. Not attacked by acids, dissolves only in aqua regia. Discovered in 1803 by W.H. Wollaston.
Atomic Number45
Atomic Weight102.9055
Mass Number103
Group9
Period5
Blockd
Protons45 p+
Neutrons58 n0
Electrons45 e-
Rhodium powder pressed melted.jpg Animated Bohr Model Enhanced Bohr Model Bohr Model Orbital Diagram

Properties

Atomic Radius
135 pm
Atomic Volume
Covalent Radius
125 pm
Metallic Radius
125 pm
Ionic Radius
66.5 pm
Crystal Radius
80.5 pm
Van der Waals radius
210 pm
Density
12.4 g/cm³
Boiling Point
4,000 K
Melting Point
2,239 K
Electrons per shell2, 8, 18, 16, 1
Electronegativity
2.28
Electrophilicity
1.4609827901818 eV/particle
Proton Affinity
768 kJ/mol
Electron Affinity
Ionization Potential
Heat of Vaporization
494 kJ/mol
Heat of Fusion
21.8 kJ/mol
Heat of Formation
556 kJ/mol
Molar Heat Capacity
24.98 J/(mol K)
Specific Heat Capacity
0.243 J/(g⋅K)
Thermal Conductivity
Gas Basicity
745.4 kJ/mol
Dipole Polarizability
66 a₀
C6 Dispersion Coefficient
Oxidation States-1, 1, 2, 3, 4, 5, 6
Color
Silver
Crystal StructureFace Centered Cubic (FCC)
Lattice Constant
3.8 Å
Bulk Modulus
Electrical Resistivity
Electron Configuration[Kr] 4d8 5s1
Magnetic Ordering
Magnetic Susceptibility
PhaseSolid
Poisson Ratio
Shear Modulus
Young's Modulus
Allotropes
Alternate Names
Adiabatic Index
Appearance
Electric Conductivity
Critical Pressure
Critical Temperature
Curie Point
Electrical
Hardness
Magnetic Susceptibility
Magnetic
Neel Point
Neutron Cross Section
Neutron Mass Absorption
Gas Phase
Quantum Numbers
Refractive Index
Space Group
Speed of Sound
Superconducting Point
Thermal Expansion
Valence Electrons
Classification
CategoryTransition metals, Transition metals
CAS GroupVIIIA
IUPAC GroupVIII
Glawe Number63
Mendeleev Number64
Pettifor Number66
Geochemical Classnoble metal
Goldschmidt Classsiderophile
Radioactivity
RadioactiveNo
Decay Mode
Half-Life
Lifetime
Abundance
Abundance in Earth's crust
0.001 mg/kg
Abundance in Oceans
Abundance in Human Body
Abundance in Meteor
Abundance in Sun
Abundance in Universe6×10-8%

Isotopes of Rhodium

Stable Isotopes
103Rh
Unstable Isotopes
89Rh 90Rh 91Rh 92Rh 93Rh 94Rh 95Rh 96Rh 97Rh 98Rh 99Rh 100Rh 101Rh 102Rh 104Rh 105Rh 106Rh 107Rh 108Rh 109Rh 110Rh 111Rh 112Rh 113Rh 114Rh 115Rh 116Rh 117Rh 118Rh 119Rh 120Rh 121Rh 122Rh

History

Rhodium was discovered in 1803 by William Hyde Wollaston in London. He used crude platinum ore presumably obtained from South America. The introduction of the three way catalytic converter by Volvo in 1976 increased the demand for rhodium. From the Greek word rhodon, rose

DiscoverersWilliam Wollaston
Discovery LocationEngland
Discovery Year1803
Name OriginGreek: rhodon (rose). Its salts give a rosy solution.
Rhodium is considered to be non-toxic
Rhodium metal does not normally form an oxide, even when heated

Uses

The element's major use is as one of the catalysts in the three-way catalytic converters in automobiles. Rhodium is used as an alloying agent for hardening and improving the corrosion resistance of platinum and palladium. It is also used as a filter in mammography systems because of the characteristic X-rays it produces. Rhodium is also used for jewelry and for decorations. Used as a coating to prevent wear on high quality science equipment and with platinum to make thermocouples.

Sources

Obtained as a by-product of nickel production.