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About Rhodium

Rhodium Bohr

Rhodium is a hard, durable metal with a shiny silver appearance and high resistance to corrosion. It is one of the rarest metals in the Earth’s crust, a factor that, along with its value for many applications, ensures its extremely high cost. The majority of new rhodium produced is used to produce three-way catalytic converters, where it is more efficient than other platinum group elements at reducing nitrogen oxides. Additionally, rhodium-based catalysts are widely used in industrial processes and other organic chemistry applications.

The remaining rhodium is used as an alloying agent that improves the corrosion resistance and increases the hardness of platinum and palladium, or used ornamentally. Rhodium-containing alloys are used in spark plugs, advanced laboratory equipment, and in thermocouples. In jewelry manufacturing, extremely thin layers of the precious metal are electroplated onto white gold or platinum to give a reflective white surface, a process known as “rhodium flashing”.

Platinum first came to Europe as platina, grey metallic crumbs that were unusable to metalworkers in their native form. Initially, few people could convert platina to workable platinum, and the process involved was a carefully guarded secret. The problem with early platina processing had been that the final material produced did not seem to have consistent properties--a problem solved when it was recognized that platina actually included several different metals. William Hyde Wollaston, an English chemist, was the first to isolate rhodium from platina samples and named the element based on the rose-red color of one of its compounds.

Like other platinum group metals, rhodium is typically obtained for commercial use as a byproduct from nickel and copper mining and processing, but can also be obtained from ores rich in platinum and alluvial deposits. Along with ruthenium and palladium, rhodium is a decomposition product of uranium and could theoretically be recovered from spent nuclear fuel, but the problems inherent in working with radioactive materials make this an impractical source for the rare element.


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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 in compound forms with purities ranging 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. Rhodium oxides is an insoluble rhodium source available in powder and dense pellet form for such uses as optical coating and thin film applications Rhodium fluoride is another insoluble form of 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 Properties

Rhodium(Rh) atomic and molecular weight, atomic number and elemental symbolRhodium is a Block D, Group 9, Period 5 element. Rhodium Bohr Model. Rhodium was first discovered by William Wollaston in 1803. The name rhodium originates from the Greek word 'Rhodon,' which means rose.

Symbol: Rh
Atomic Number: 45
Atomic Weight: 102.9055
Element Category: transition metal
Group, Period, Block: 9, 5, d
Color: silvery white metallic/ silvery-white
Other Names: Rodio, Ródio
Melting Point: 1964 °C, 3567 °F, 2237 K
Boiling Point: 3695 °C, 6683 °F, 3968 K
Density: 12.41 g·cm3
Liquid Density @ Melting Point: 10.7 g·cm3
Density @ 20°C: 12.4 g/cm3
Density of Solid: 12450 kg·m3
Specific Heat: 0.24 (kJ/kg K)
Superconductivity Temperature: N/A
Triple Point: N/A
Critical Point: N/A
Heat of Fusion (kJ·mol-1): 21.55
Heat of Vaporization (kJ·mol-1): 494.34
Heat of Atomization (kJ·mol-1): 555.59
Thermal Conductivity: 150 W·m-1·K-1
Thermal Expansion: (25 °C) 8.2 µm·m-1·K-1
Electrical Resistivity: (0 °C) 43.3 nΩ·m
Tensile Strength: N/A
Molar Heat Capacity: 24.98 J·mol-1·K-1
Young's Modulus: 380 GPa
Shear Modulus: 150 GPa
Bulk Modulus: 275 GPa
Poisson Ratio: 0.26
Mohs Hardness: 6
Vickers Hardness: 1246 MPa
Brinell Hardness: 1100 MPa
Speed of Sound: (20 °C) 4700 m·s-1
Pauling Electronegativity: 2.28
Sanderson Electronegativity: N/A
Allred Rochow Electronegativity: 1.45
Mulliken-Jaffe Electronegativity: N/A
Allen Electronegativity: N/A
Pauling Electropositivity: 1.72
Reflectivity (%): 84
Refractive Index: N/A
Electrons: 45
Protons: 45
Neutrons: 58
Electron Configuration: [Kr] 4d8 5s1
Atomic Radius: 134 pm
Atomic Radius,
non-bonded (Å):
Covalent Radius: 142±7 pm
Covalent Radius (Å): 1.34
Van der Waals Radius: 200 pm
Oxidation States: 6, 5, 4, 3, 2, 1, -1 (amphoteric oxide)
Phase: Solid
Crystal Structure: face-centered cubic
Magnetic Ordering: paramagnetic
Electron Affinity (kJ·mol-1) 109.665
1st Ionization Energy: 719.68 kJ·mol-1
2nd Ionization Energy: 1744.47 kJ·mol-1
3rd Ionization Energy: 2996.86 kJ·mol-1
CAS Number: 7440-16-6
EC Number: 231-125-0
MDL Number: MFCD00011201
Beilstein Number: N/A
SMILES Identifier: [Rh]
InChI Identifier: InChI=1S/Rh
PubChem CID: 23948
ChemSpider ID: 22389
Earth - Total: 252 ppb 
Mercury - Total: 194 ppb
Venus - Total: 265 ppb
Earth - Seawater (Oceans), ppb by weight: N/A
Earth - Seawater (Oceans), ppb by atoms: N/A
Earth -  Crust (Crustal Rocks), ppb by weight: 0.7
Earth -  Crust (Crustal Rocks), ppb by atoms: 0.1
Sun - Total, ppb by weight: 2
Sun - Total, ppb by atoms: 0.02
Stream, ppb by weight: N/A
Stream, ppb by atoms: N/A
Meterorite (Carbonaceous), ppb by weight: 180
Meterorite (Carbonaceous), ppb by atoms: 40
Typical Human Body, ppb by weight: N/A
Typical Human Body, ppb by atom: N/A
Universe, ppb by weight: 0.6
Universe, ppb by atom: 0.007
Discovered By: William Hyde Wollaston
Discovery Date: 1804
First Isolation: William Hyde Wollaston (1804)

Health, Safety & Transportation Information for Rhodium

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. The below information applies to elemental (metallic) Rhodium.

Safety Data
Signal Word Danger
Hazard Statements H228
Hazard Codes N/A
Risk Codes N/A
Safety Precautions N/A
RTECS Number VI9069000
Transport Information N/A
WGK Germany 3
Globally Harmonized System of
Classification and Labelling (GHS)
Review and Print SDS for Rhodium Metal


Date Created: 05/15/2015
Date Revised: 05/15/2015


Product Name: Rhodium Metal

Product Number: All applicable American Elements product codes, e.g. RH-M-02, RH-M-03, RH-M-04, RH-M-05

CAS #: 7440-16-6

Relevant identified uses of the substance: Scientific research and development

Supplier details:
American Elements
1093 Broxton Ave. Suite 2000
Los Angeles, CA 90024
Tel: +1 310-208-0551
Fax: +1 310-208-0351

Emergency telephone number:
Domestic, North America +1 800-424-9300
International +1 703-527-3887


Classification of the substance or mixture
Classification according to Regulation (EC) No 1272/2008
The substance is not classified as hazardous to health or the environment according to the CLP regulation.
Classification according to Directive 67/548/EEC or Directive 1999/45/EC
Not applicable
Information concerning particular hazards for human and environment:
No information known.
Hazards not otherwise classified
No information known.
Label elements
Labelling according to Regulation (EC) No 1272/2008
Not applicable
Hazard pictograms
Not applicable
Signal word
Not applicable
Hazard statements
Not applicable
WHMIS classification
Not controlled
Classification system
HMIS ratings (scale 0-4)
(Hazardous Materials Identification System)

Health (acute effects) = 0
Flammability = 0
Physical Hazard = 0
Other hazards
Results of PBT and vPvB assessment
PBT: Not applicable.
vPvB: Not applicable.


Chemical characterization: Substances
CAS# Description:
7440-16-6 Rhodium
Identification number(s):
EC number: 231-125-0


Description of first aid measures
General information
No special measures required.
After inhalation
Seek medical treatment in case of complaints.
After skin contact
Generally the product does not irritate the skin.
After eye contact
Rinse opened eye for several minutes under running water. If symptoms persist, consult a doctor.
After swallowing
If symptoms persist consult doctor.
Information for doctor
Most important symptoms and effects, both acute and delayed
No further relevant information available.
Indication of any immediate medical attention and special treatment needed
No further relevant information available


Extinguishing media
Suitable extinguishing agents
Special powder for metal fires. Do not use water.
For safety reasons unsuitable extinguishing agents
Special hazards arising from the substance or mixture
If this product is involved in a fire, the following can be released:
Rhodium oxide
Advice for firefighters
Protective equipment:
No special measures required.


Personal precautions, protective equipment and emergency procedures
Not required.
Environmental precautions:
Do not allow material to be released to the environment without proper governmental permits.
Do not allow product to reach sewage system or any water course.
Do not allow to penetrate the ground/soil.
Methods and material for containment and cleaning up:
Pick up mechanically.
Prevention of secondary hazards:
No special measures required.
Reference to other sections
See Section 7 for information on safe handling
See Section 8 for information on personal protection equipment.
See Section 13 for disposal information.


Precautions for safe handling
Keep container tightly sealed.
Store in cool, dry place in tightly closed containers.
Information about protection against explosions and fires:
No special measures required.
Conditions for safe storage, including any incompatibilities
Requirements to be met by storerooms and receptacles:
No special requirements.
Information about storage in one common storage facility:
No information known.
Further information about storage conditions:
Keep container tightly sealed.
Store in cool, dry conditions in well sealed containers.
Specific end use(s)
No further relevant information available.


Additional information about design of technical systems:
No further data; see section 7.
Control parameters
Components with limit values that require monitoring at the workplace: 7440-16-6 Rhodium (100.0%)
PEL (USA) Long-term value: 0.1 mg/m³
REL (USA) Long-term value: 0.1 mg/m³ as Rh
TLV (USA) Long-term value: 1 mg/m³
EL (Canada) Short-term value: 0.3 mg/m³
Long-term value: 0.1 mg/m³ as Rh
EV (Canada) Long-term value: 1* 0.01** mg/m³ *metal,water-insol. compds.;**water-soluble compds
Additional information: No data
Exposure controls
Personal protective equipment
General protective and hygienic measures
The usual precautionary measures for handling chemicals should be followed.
Maintain an ergonomically appropriate working environment.
Breathing equipment: Not required.
Protection of hands: Not required.
Penetration time of glove material (in minutes)
Not determined
Eye protection: Safety glasses
Body protection: Protective work clothing.


Information on basic physical and chemical properties
General Information
Form: Solid in various forms
Color: Not determined
Odor: Not determined
Odor threshold: Not determined.
pH-value: Not applicable.
Change in condition
Melting point/Melting range: 1966 °C (3571 °F)
Boiling point/Boiling range: 3695 °C (6683 °F)
Sublimation temperature / start: Not determined
Flammability (solid, gaseous): Not determined.
Ignition temperature: Not determined
Decomposition temperature: Not determined
Auto igniting: Not determined.
Danger of explosion: Not determined.
Explosion limits:
Lower: Not determined
Upper: Not determined
Vapor pressure at 20 °C (68 °F): 0 hPa
Density at 20 °C (68 °F): 12.41 g/cm³ (103.561 lbs/gal)
Relative density: Not determined.
Vapor density: Not applicable.
Evaporation rate: Not applicable.
Solubility in / Miscibility with Water: Not determined
Partition coefficient (n-octanol/water): Not determined.
dynamic: Not applicable.
kinematic: Not applicable.
Other information
No further relevant information available.


No information known.
Chemical stability
Stable under recommended storage conditions.
Thermal decomposition / conditions to be avoided:
Decomposition will not occur if used and stored according to specifications.
Possibility of hazardous reactions
No dangerous reactions known
Conditions to avoid
No further relevant information available.
Incompatible materials:
No information known.
Hazardous decomposition products:
Rhodium oxide


Information on toxicological effects
Acute toxicity: No effects known.
LD/LC50 values that are relevant for classification: No data
Skin irritation or corrosion: Powder: irritant effect
Eye irritation or corrosion: Powder: irritant effect
Sensitization: No sensitizing effects known.
Germ cell mutagenicity: No effects known.
ACGIH A4: Not classifiable as a human carcinogen: Inadequate data on which to classify the agent in terms of its carcinogenicity in humans and/or animals.
Reproductive toxicity: No effects known.
Specific target organ system toxicity - repeated exposure: No effects known.
Specific target organ system toxicity - single exposure: No effects known.
Aspiration hazard: No effects known.
Subacute to chronic toxicity: No effects known.
Additional toxicological information:
To the best of our knowledge the acute and chronic toxicity of this substance is not fully known


Aquatic toxicity:
No further relevant information available.
Persistence and degradability
No further relevant information available.
Bioaccumulative potential
No further relevant information available.
Mobility in soil
No further relevant information available.
Additional ecological information:
General notes:
Do not allow material to be released to the environment without proper governmental permits.
Do not allow undiluted product or large quantities to reach ground water, water course or sewage system.
Avoid transfer into the environment.
Results of PBT and vPvB assessment
PBT: Not applicable.
vPvB: Not applicable.
Other adverse effects
No further relevant information available


Waste treatment methods
Consult state, local or national regulations to ensure proper disposal.
Uncleaned packagings:
Disposal must be made according to official regulations.


Not applicable
UN proper shipping name
Not applicable
Transport hazard class(es)
Not applicable
Packing group
Not applicable
Environmental hazards:
Not applicable.
Special precautions for user
Not applicable.
Transport in bulk according to Annex II of MARPOL73/78 and the IBC Code
Not applicable.
Transport/Additional information:
Marine Pollutant (DOT):
UN "Model Regulation":


Safety, health and environmental regulations/legislation specific for the substance or mixture
National regulations
All components of this product are listed in the U.S. Environmental Protection Agency Toxic Substances Control Act Chemical substance Inventory.
All components of this product are listed on the Canadian Domestic Substances List (DSL).
SARA Section 313 (specific toxic chemical listings)
Substance is not listed.
California Proposition 65
Prop 65 - Chemicals known to cause cancer
Substance is not listed.
Prop 65 - Developmental toxicity
Substance is not listed.
Prop 65 - Developmental toxicity, female
Substance is not listed.
Prop 65 - Developmental toxicity, male
Substance is not listed.
Information about limitation of use:
For use only by technically qualified individuals.
Other regulations, limitations and prohibitive regulations
Substance of Very High Concern (SVHC) according to the REACH Regulations (EC) No. 1907/2006.
Substance is not listed.
The conditions of restrictions according to Article 67 and Annex XVII of the Regulation (EC) No 1907/2006 (REACH) for the manufacturing, placing on the market and use must be observed.
Substance is not listed.
Annex XIV of the REACH Regulations (requiring Authorisation for use)
Substance is not listed.
REACH - Pre-registered substances
Substance is listed.
Chemical safety assessment:
A Chemical Safety Assessment has not been carried out.


Safety Data Sheet according to Regulation (EC) No. 1907/2006 (REACH). The above information is believed to be correct but does not purport to be all inclusive and shall be used only as a guide. The information in this document is based on the present state of our knowledge and is applicable to the product with regard to appropriate safety precautions. It does not represent any guarantee of the properties of the product. American Elements shall not be held liable for any damage resulting from handling or from contact with the above product. See reverse side of invoice or packing slip for additional terms and conditions of sale. COPYRIGHT 1997-2016 AMERICAN ELEMENTS. LICENSED GRANTED TO MAKE UNLIMITED PAPER COPIES FOR INTERNAL USE ONLY.

Rhodium Isotopes

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

Nuclide Isotopic Mass Half-Life Mode of Decay Nuclear Spin Magnetic Moment Binding Energy (MeV) Natural Abundance
(% by atom)
89Rh 88.94884(48)# 10# ms [>1.5 µs] ß+ to 89Ru 7/2+# N/A 716.96 -
90Rh 89.94287(54)# 15(7) ms [12(+9-4) ms] ß+ to 90Ru 0+# N/A 730.63 -
91Rh 90.93655(43)# 1.74(14) s ß+ to 91Ru 7/2+# N/A 744.29 -
92Rh 91.93198(43)# 4.3(13) s ß+ to 92Ru (6+) N/A 757.03 -
93Rh 92.92574(43)# 11.9(7) s ß+ to 93Ru 9/2+# N/A 770.7 -
94Rh 93.92170(48)# 70.6(6) s ß+ to 94Ru; ß+ + p to 93Tc (2+,4+) N/A 782.5 -
95Rh 94.91590(16) 5.02(10) min ß+ to 95Ru (9/2)+ N/A 796.17 -
96Rh 95.914461(14) 9.90(10) min ß+ to 96Ru (6+) N/A 805.18 -
97Rh 96.91134(4) 30.7(6) min ß+ to 97Ru 9/2+ N/A 816.06 -
98Rh 97.910708(13) 8.72(12) min ß+ to 98Ru (2)+ N/A 825.07 -
99Rh 98.908132(8) 16.1(2) d EC to 99Ru 1/2- N/A 835.01 -
100Rh 99.908122(20) 20.8(1) h EC to 100Ru 1- N/A 843.09 -
101Rh 100.906164(18) 3.3(3) y EC to 101Ru; IT 1/2- N/A 858.62 -
102Rh 101.906843(5) 207.0(15) d EC to 102Ru; ß- to 102Pd (1-,2-) 4.04 866.7 -
103Rh 102.905504(3) Observationally Stable - 1/2- -0.0884 874.78 100
104Rh 103.906656(3) 42.3(4) s EC to 104Ru; ß- to 104Pd 1+ N/A 882.86 -
105Rh 104.905694(4) 35.36(6) h ß- to 105Pd 7/2+ 4.45 890.93 -
106Rh 105.907287(8) 29.80(8) s ß- to 106Pd 1+ N/A 899.01 -
107Rh 106.906748(13) 21.7(4) min ß- to 107Pd 7/2+ N/A 907.09 -
108Rh 107.90873(11) 16.8(5) s ß- to 108Pd 1+ N/A 915.17 -
109Rh 108.908737(13) 80(2) s ß- to 109Pd 7/2+ N/A 923.25 -
110Rh 109.91114(5) 28.5(15) s ß- to 110Pd (>3)(+#) N/A 922.01 -
111Rh 110.91159(3) 11(1) s ß- to 111Pd (7/2+) N/A 930.09 -
112Rh 111.91439(6) 3.45(37) s ß- to 112Pd 1+ N/A 938.17 -
113Rh 112.91553(5) 2.80(12) s ß- to 113Pd (7/2+) N/A 946.25 -
114Rh 113.91881(12) 1.85(5) s ß- to 114Pd; ß- + n to 113Pd 1+ N/A 954.33 -
115Rh 114.92033(9) 0.99(5) s ß- to 115Pd (7/2+)# N/A 953.09 -
116Rh 115.92406(15) 0.68(6) s ß- to 116Pd; ß- + n to 115Pd 1+ N/A 961.17 -
117Rh 116.92598(54)# 0.44(4) s ß- to 117Pd (7/2+)# N/A 969.25 -
118Rh 117.93007(54)# 310(30) ms ß- to 118Pd (4-10)(+#) N/A 968.01 -
119Rh 118.93211(64)# 300# ms [>300 ns] ß- to 119Pd 7/2+# N/A 976.09 -
120Rh 119.93641(64)# 200# ms [>300 ns] ß- to 120Pd N/A N/A 984.17 -
121Rh 120.93872(97)# 100# ms [>300 ns] ß- to 121Pd 7/2+# N/A 992.24 -
122Rh 121.94321(75)# 50# ms [>300 ns] Unknwon N/A N/A 991.01 -