Rhodium Elemental Symbol

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Rhodium Rhodium Rodio Ródio Rodio Rhodium

Rhodium(Rh) atomic and molecular weight, atomic number and elemental symbolRhodium is a Block D, Group 9, Period 5 element. Rhodium Bohr ModelThe number of electrons in each of Rhodium's shells is 2, 8, 18, 16, 1 and its electron configuration is [Kr] 4d8 5s1. Elemental RhodiumThe rhodium atom has a radius of 134.5.pm and its Van der Waals radius is 200.pm. In its elemental form, CAS 7440-16-6, rhodium has a silvery white metallic appearance. Rhodium is a member of the platinum group of metals. It has a higher melting point than platinum, but a lower density. Rhodium is found in ores mixed with other metals such as palladium, silver, platinum, and gold. Rhodium was first discovered by William Wollaston in 1803. The name Rhodium originates from the Greek word 'Rhodon,' which means rose.

Rhodium 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. High Purity (99.999%) Rhodium Oxide (Rh2O3) PowderRhodium 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). High Purity (99.999%) Rhodium (Rh) Sputtering TargetElemental or metallic forms include pellets, rod, wire and granules for evaporation source material purposes. Rhodium 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 powder and dense pellet form 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 also available in soluble forms including chlorides, nitrates and acetates. These compounds can be manufactured as solutions at specified stoichiometries.

Rhodium is not toxic in its elemental form; however, safety data for Rhodium 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 Products tab below.

  • Properties
  • Safety Data
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  • Research
  • Isotopes
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Rhodium Properties

Symbol: Rh Melting Point: 2237 K, 1964 °C, 3567 °F
Atomic Number: 45 Boiling Point: 3968 K, 3695 °C, 6683 °F
Atomic Weight: 102.90550 Density: 12.41 g·cm−3
Element Category: transition metal Liquid Density @ Melting Point: 10.7 g·cm−3
Group, Period, Block: 9, 5, d Specific Heat: 0.24 (kJ/kg K)
    Heat of Vaporization 494.34 kJ mol-1
CHEMICAL STRUCTURE Heat of Fusion 21.55 kJ mol-1
Electrons: 45 Thermal Conductivity: 150 W·m−1·K−1
Protons: 45 Thermal Expansion: (25 °C) 8.2 µm·m−1·K−1
Neutrons: 58 Electrical Resistivity: (0 °C) 43.3 nΩ·m
Electron Configuration: [Kr] 4d85s1 Electronegativity: 2.28 (Pauling scale)
Atomic Radius: 134 pm Tensile Strength:  
Covalent Radius: 142±7 pm Molar Heat Capacity: 24.98 J·mol−1·K−1
Van der Waals radius: 200.pm Young's Modulus: 380 GPa
Oxidation States: 6, 5, 4, 3, 2, 1, -1 (amphoteric oxide) Shear Modulus: 150 GPa
Phase: Solid Bulk Modulus: 275 GPa
Crystal Structure: face-centered cubic Poisson Ratio: 0.26
Magnetic Ordering: paramagnetic Mohs Hardness: 6.0
1st Ionization Energy: 719.68 kJ mol-1 Vickers Hardness: 1246 MPa
2nd Ionization Energy: 1744.47 kJ mol-1 Brinell Hardness: 1100 MPa
3rd Ionization Energy: 2996.86 kJ mol-1 Speed of Sound: (20 °C) 4700 m·s−1
CAS Number: 7440-16-6 Abundance in typical human body, by weight: N/A
ChemSpider ID: 22389 Abundance in typical human body, by atom: N/A
PubChem CID: 23948 Abundance in universe, by weight: 0.6 ppb
MDL Number: MFCD00011201 Abundance in universe, by atom: 0.007 ppb
EC Number: 231-125-0 Discovered By: William Hyde Wollaston
Beilstein Number: N/A Discovery Date: 1804
SMILES Identifier: [Rh]  
InChI Identifier: InChI=1S/Rh Other Names: Rodio, Ródio

Rhodium Products

Metal Forms  •  Compounds  •  Alloys  •  Oxide Forms  •  Organometallic Compounds
Sputtering Targets  •  Nanomaterials  •  Semiconductor Materials

Metal Forms

Rhodium Balls
Rhodium Bands
Rhodium Bars
Rhodium Bits
Rhodium Black
Rhodium Board
Rhodium Briquette
Rhodium Capsules
Rhodium Chunk
Rhodium Circle
Rhodium Coil
Rhodium Coins
Rhodium Concentrate
Rhodium Crucibles
Rhodium Cylinder
Rhodium Disc
Rhodium Dust
Rhodium Flake
Rhodium Flanges
Rhodium Foil
Rhodium Fragments
Rhodium Grain
Rhodium Granules
Rhodium Ingot
Rhodium Lump
Rhodium Mesh
Rhodium Metal
Rhodium Microfoil
Rhodium Microleaf
Rhodium Nugget
Rhodium on Alumina
Rhodium Particles
Rhodium Parts
Rhodium Pebbles
Rhodium Pellets
Rhodium Pieces
Rhodium Pills
Rhodium Plate
Rhodium Powder
Rhodium Precipitate
Rhodium Puck
Rhodium Residue
Rhodium Ribbon
Rhodium Rings
Rhodium Rocks
Rhodium Rod
Rhodium Samples
Rhodium Scraps
Rhodium Segments
Rhodium Shaving
Rhodium Sheets
Rhodium Shot
Rhodium Sleeves
Rhodium Slugs
Rhodium Specimens
Rhodium Spheres
Rhodium Sponges
Rhodium Spring
Rhodium Strip
Rhodium Tape
Rhodium Tube
Rhodium Wafer
Rhodium Wedding Rings
Rhodium Wire
Ultra Thin Rhodium Foil


Ammonium Aquopentachlororhodate(III)
Ammonium Hexachlororhodate(III)
Ammonium Hexachlororhodate(III) Hydrate
Diammonium Sodium Hexanitrorhodate(III)
Pentaamminechlororhodium(III) Dichloride
Potassium Hexanitrorhodate(III)
Potassium Pentachlororhodate(III)
Potassium Pentachlororhodate(III) Hydrate
Potassium Hexanitrorhodate(III)
Rhodium Acetate
Rhodium Acetate Solution
Rhodium Bromide
Rhodium Bromide Hydrate
Rhodium Carbide
Rhodium Chloride
Rhodium Chloride Solution
Rhodium Fluoride
Rhodium Iodide
Rhodium Nitrate
Rhodium Nitrate Solution
Rhodium Oxide
Rhodium Oxide Hydrate
Rhodium Phosphate Solution
Rhodium Sulfate
Rhodium Sulfate Solution
Rhodium Trichloride Hydrate
Sodium Hexabromorhodate(III) Hydrate
Sodium Hexachlororhodate(III) Dodecahydrate
Organometallic Compounds

(1,5-Cyclooctadiene)bis(triphenylphosphine) rhodium(I) Hexafluorophosphate Dichloromethane Complex
(Bicyclo[2.2.1]hepta-2,5-diene)-rhodium(I) Chloride Dimer
(Bicyclo[2.2.1]hepta-2,5-diene)[(2S,3S)-bis(diphenylphosphino)butane]rhodium(I) Perchlorate
(Bicyclo[2.2.1]hepta-2,5-diene)[1,1'-bis(diphenylphosphino)ferrocene]rhodium(I) Perchlorate
(Bicyclo[2.2.1]hepta-2,5-diene)[1,4-bis(diphenylphosphino)butane]rhodium(I) Tetrafluoroborate
(R,R,R,R)-2,3-Bis(2,5-dimethyl-phospholanyl)benzo[b]thiophene Cyclooctadiene Rhodium(I) Tetrafluoroborate Complex
(S,S,S,S)-2,3-Bis(2,5-dimethyl-phospholanyl)benzo[b]thiophene Cyclooctadiene Rhodium(I) Tetrafluoroborate Complex
1,2-Bis[(2R,5R)-2,5-diethylphospholano]benzene(1,5-cyclooctadiene)rhodium(I) tetrafluoroborate
1,2-Bis[(2R,5R)-2,5-diethylphospholano]benzene(1,5-cyclooctadiene)rhodium(I) trifluoromethanesulfonate
1,2-Bis[(2R,5R)-2,5-diisopropylphospholano]benzene(1,5-cyclooctadiene)rhodium(I) tetrafluoroborate
1,2-Bis[(2R,5R)-2,5-dimethylphospholano]benzene(cyclooctadiene) rhodium(I) trifluoromethanesulfonate
(cyclooctadiene)rhodium(I) tetrafluoroborate

1,2-Bis[(2R,5R)-2,5-diphenylphospholano]ethane(1,5-cyclooctadiene)rhodium(I) tetrafluoroborate
1,2-Bis[(2S,5S)-2,5-diethylphospholano]benzene(1,5-cyclooctadiene)rhodium(I) tetrafluoroborate
1,2-Bis[(2S,5S)-2,5-diethylphospholano]benzene(1,5-cyclooctadiene)rhodium(I) Trifluoromethanesulfonate
(cyclooctadiene)rhodium(I) Tetrafluoroborate

(cyclooctadiene)rhodium(I) Trifluoromethanesulfonate

(cyclooctadiene)rhodium(I) Tetrafluoroborate

µ-Dichlorotetraethylene Dirhodium(I)
Bis(1,5-cyclooctadiene)dirhodium(I) dichloride
Bis(1,5-cyclooctadiene)rhodium(I) hexafluoroantimonate
Bis(1,5-cyclooctadiene)rhodium(I) tetrafluoroborate
Bis(1,5-cyclooctadiene)rhodium(I) Tetrafluoroborate Hydrate
Bis(1,5-cyclooctadiene)rhodium(I) tetrakis[bis(3,5-trifluoromethyl)phenyl]borate
Bis(1,5-cyclooctadiene)rhodium(I) Trifluoromethanesulfonate

Bis(norbornadiene)rhodium(I) tetrafluoroborate
Bis(norbornadiene)rhodium(I) trifluoromethanesulfonate
Bis(triphenylphosphine)rhodium(I) Carbonyl Chloride
Bis[rhodium(a,a,a',a'-tetramethyl-1,3-benzenedipropionic acid)]



Chloro(1,5-cyclooctadiene)rhodium(I) Dimer
Chlorobis(2-phenylpyridine)rhodium(III) Dimer
Organometallic Compounds (continued)

Chlorobis(ethylene)rhodium(I) dimer
Chlorotris[(3,3',3''-phosphinidynetris(benzenesulfonato)] rhodium(I) Nonasodium Salt Hydrate

Dichloropentamethylcyclopentadienylrhodium(III) Dimer
Hexa(acetato)-µ-oxotris(aqua)trirhodium(III) acetate
(0) Hexadecacarbonyl
Hydridotetrakis(triphenylphosphine) rhodium(I)
Hydroxy(cyclooctadiene)rhodium(I) dimer
Methoxy(cyclooctadiene)rhodium(I) dimer
Pentamethylcyclopentadienylrhodium(III) chloride,dimer l
Rhodium 2-Ethylhexanoate
Rhodium(III) 2,4-pentanedionate
Rhodium Acetylacetonate
Rhodium(II) Heptafluorobutyrate dimer
Rhodium(II) Hexanoate, Dimer
Rhodium Octanoate Dimer
Rhodium Trifluoroacetate Dimer
Rhodium Trifluoromethanesulfonate
Rhodium Trimethylacetate Dimer
Tetracarbonyldi-µ-chlorodirhodium(I), Rh
Tetrarhodium Dodecacarbonyl
trans-Dichlorotetrakis(pyridine)rhodium(III) chloride

Triphenylphosphine(2,5-norbornadiene)rhodium(I) tetrafluoroborate
cyclopentadienylrhodium(III) hexafluoroantimonate

Tris(ethylenediamine)rhodium(III) Chloride Trihydrate
Tris(ethylenediamine)rhodium(III) Nitrate
Tris(triphenylphosphine)rhodium(I) Carbonyl Hydride
Tris(triphenylphosphine)rhodium(I) Chloride
[1,4-Bis(diphenylphosphino)butane](1,5-cyclooctadiene)rhodium(I) Tetrafluoroborate
[Tris(dimethylphenylphosphine)](2,5-norbornadiene)rhodium(I) hexafluorophosphate


Cobalt Rhodium Zirconium Alloy
Iron Nickel Rhodium Alloy
Iron Rhodium Alloy
Manganese Rhodium Alloy
Molybdenum Rhodium Alloy
Platinum Rhodium Alloy
Platinum Rhodium Foil
Platinum Rhodium Wire

Sputtering Targets

Rhodium Oxide Rotatable Sputtering Target
Rhodium Oxide Sputtering Target
Rhodium Phosphide Sputtering Target
Rhodium Rotatable Sputtering Target
Rhodium Selenide Sputtering Target
Rhodium Sputtering Target
Rhodium Telluride Sputtering Target

Oxide Forms

Rhodium Oxide Nanopowder
Rhodium Oxide Particles
Rhodium Oxide Pellets
Rhodium Oxide Pieces
Rhodium Oxide Powder
Rhodium Oxide Rotatable Sputtering Target
Rhodium Oxide Shot
Rhodium Oxide Sputtering Target
Rhodium Oxide Tablets

Crystal/ Semiconductor Materials

Rhodium Phosphide
Rhodium Selenide
Rhodium Sulfide
Rhodium Telluride


Rhodium Nanofoil
Rhodium Nanoparticles Entrapped in Aluminum Hydroxide Matrix
Rhodium Nanorods
Rhodium Oxide Nanopowder

Recent Research & Development for Rhodium

  • Iwona A. Rutkowska, Margaretta D. Koster, Gary J. Blanchard, Pawel J. Kulesza, Enhancement of ethanol oxidation at Pt and PtRu nanoparticles dispersed over hybrid zirconia-rhodium supports, Journal of Power Sources, Volume 272, 25 December 2014
  • Basu D. Panthi, Stephen L. Gipson, Andreas Franken, Structural Studies of Some Rhodium(III) Acyl Complexes Containing Bidentate Phosphines, Inorganica Chimica Acta, Available online 7 October 2014
  • Elizaveta P. Shestakova, Yuri S. Varshavsky, Victor N. Khrustalev, Galina L. Starova, Sergei N. Smirnov, Rhodium(III) cationic methyl complexes containing dimethylformamide ligand, cis-[Rh(β-diket)(PPh3)2(CH3)(DMF)][BPh4] (β-diket = acetylacetonate or benzoylacetonate), in comparison with their acetonitrile analogs, Journal of Organometallic Chemistry, Available online 7 October 2014
  • Stephany García, Jannise J. Buckley, Richard L. Brutchey, Simon M. Humphrey, Effect of microwave heating on the synthesis of rhodium nanoparticles in ionic liquids, Inorganica Chimica Acta, Volume 422, 1 October 2014
  • Arnab Kumar Maity, Manish Bhattacharjee, Sujit Roy, SnCl2 insertion into Ir–Cl and Rh–Cl bonds: Synthesis, characterization and catalytic activity of three-legged piano-stool trichlorostannyl iridium and rhodium complexes, Journal of Organometallic Chemistry, Volume 768, 1 October 2014
  • Song-Il O, Jun-Min Yan, Hong-Li Wang, Zhi-Li Wang, Qing Jiang, Ni/La2O3 catalyst containing low content platinum–rhodium for the dehydrogenation of N2H4·H2O at room temperature, Journal of Power Sources, Volume 262, 15 September 2014
  • Srikanth Cheemalapati, Shen-Ming Chen, M. Ajmal Ali, Fahad M.A. Al-Hemaid, Enhanced electrocatalytic oxidation of isoniazid at electrochemically modified rhodium electrode for biological and pharmaceutical analysis, Colloids and Surfaces B: Biointerfaces, Volume 121, 1 September 2014
  • Mahesh Kalidasan, S.H. Forbes, Yurij Mozharivskyj, Mohan Rao Kollipara, Half-sandwich η6-arene ruthenium and Cp∗ rhodium/iridium compounds comprising with thioether ligands: Synthesis, spectral and molecular studies, Inorganica Chimica Acta, Volume 421, 1 September 2014
  • Hee-Chul Yang, Min-Woo Lee, Ho-Sang Hwang, Jei-Kwon Moon, Dong-Yong Chung, Study of cerium-promoted rhodium alumina catalyst as a steam reforming catalyst for treatment of spent solvents, Journal of Rare Earths, Volume 32, Issue 9, September 2014
  • Sebastian D. Pike, Indrek Pernik, Robin Theron, J. Scott McIndoe, Andrew S. Weller, Relative binding affinities of fluorobenzene ligands in cationic rhodium bisphosphine η6–fluorobenzene complexes probed using collision-induced dissociation, Journal of Organometallic Chemistry, Available online 23 August 2014

Rhodium Isotopes

Naturally occurring rhodium (Rh) has one stable isotope: 103Rh.

Nuclide Symbol Isotopic Mass Half-Life Nuclear Spin
103Rh 102.905504 Stable 1/2-