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Rhodium , including Technical Data, Safety Data and its high purity propertiesresearch, applications and other useful facts are discussed below. Scientific facts such as the atomic structure,ionization energyabundance on Earthconductivity and thermal properties are included. 

Rhodium is a member of the platinum group of metals. It has a higher melting point than platinum, but a lower density. It is alloyed with platinum and palladium in electrodes for spark plugs, advanced laboratory equipment and in thermocouples. Rhodium compounds also have catalytic uses in automotive catalytic converters. Rhodium is used as a plating metal in jewelry production to enhance the whiteness of white gold. Rhodium is available as metal and compounds with purities from 99% to 99.999% (ACS grade to ultra-high purity); metals in the form of foil, sputtering target, and rod, and compounds as submicron and nanopowder.

 Rhodium facts, including appearance, CAS #, and molecular formula and safety data, research and properties are available for many specific states, forms and shapes on the product pages listed to the left. Elemental or metallic forms include pellets, rod, wire and granules for evaporation source material purposes. Nanoparticles and nanopowders provide ultra high surface area which nanotechnology research and recent experiments demonstrate function to create new and unique properties and benefits. 

Oxides are available in forms including powders and dense pellets for such uses as optical coating and thin film applications. Oxides tend to be insoluble. Fluorides are another insoluble form for uses in which oxygen is undesirable such as metallurgy, chemical and physical vapor deposition and in some optical coatings. Rhodium is available in soluble forms including chlorides, nitrates and acetates. These compounds are also manufactured as solutions at specified stoichiometries. 

Rhodium is a Block D, Group 9, Period 5 element. The number of electrons in each of Rhodium‘s shells is 2, 8, 18, 16, 1 and its electronic configuration is [Kr] 4d8 5s1. In its elemental form rhodium‘s CAS number is 7440-16-6. The rhodium atom has a radius of and it‘s Van der Waals radius is Rhodium is not toxic. 

All elemental metals, compounds and solutions may be synthesized in ultra high purity (e.g. 99.999%) for laboratory standards, advanced electronic, thin fillm deposition using sputtering targets and evaporation materials, metallurgy and optical materials and other high technology applications. Information is provided for stable (non-radioactive) isotopesOrgano-Metallic Rhodium compounds are soluble in organic or non-aqueous solvents. See Analytical Services for information on available certified chemical and physical analysis techniques including MS-ICP, X-Ray Diffraction, PSD and Surface Area (BET) analysis. 

Rhodium was first discovered by William Wollaston in 1803. The name Rhodium, originates from the Greek word ‘Rhodon‘ which means rose.

Abundance. The following table shows the abundance of rhodium and each of its naturally occurringisotopes on Earth along with the atomic mass for each isotope.

Isotope Atomic Mass % Abundance on Earth
Rh-103 102.905504 100

The following table shows the abundance of Rhodium present in the human body and in the universe scaled to parts per billion (ppb) by weight and by atom:
  Typical Human Body Universe
by Weight no data 0.6 ppb
by Atom no data 0.007 ppb

Safety Data and Biological Role. The safety data for rhodium metalnanoparticles and its compounds can vary widely depending on the form. For potential hazard information, toxicity, and road, sea and air transportation limitations, such as DOT Hazard Class, DOT Number, EU Number, NFPA Health rating and RTECS Class, please see the specific material or compound referenced in the left margin. Rhodium compounds have no biological role.

Ionization Energy. The ionization energy for rhodium (the least required energy to release a single electron from the atom in it‘s ground state in the gas phase) is stated in the following table:

1st Ionization Energy 719.68 kJ mol-1
2nd Ionization Energy 1744.47 kJ mol-1
3rd Ionization Energy 2996.86 kJ mol-1

Conductivity. As to rhodium‘s electrical and thermal conductivity, the electrical conductivity measured as to electrical resistivity @ 20 ?C is 4.51 μΩcm and its electronegativities (or its ability to draw electrons relative to other elements) is 2.28. The thermal conductivity of rhodium is 150 W m-1 K-1.

Thermal Properties. The melting point and boiling point for rhodium are stated below. The following chart sets forth the heat of fusion, heat of vaporization and heat of atomization.

Heat of Fusion 21.55 kJ mol-1
Heat of Vaporization 494.34 kJ mol-1
Heat of Atomization 555.59 kJ mol-1

Formula Atomic Number Molecular Weight Electronegativity (Pauling) Density Melting Point Boiling Point Vanderwaals radius Ionic radius Energy of first ionization
Rh 45 102.91 g.mol-1 2.2 12.4 at 20 °C 1970 °C 3727 °C unknown 719.68 kJ.mol-1