Skip to Main Content

About Chromium

Chromium Bohr Model

When French chemist Louis Nicolas Vauquelin first received a sample of Siberian red lead in 1797, the mineral--known today as crocoite--had been in use as a pigment for over three decades, but its chemical composition had remained a subject of dispute. Vauquelin resolved the debate when he was able to isolate a new metallic element, chromium, from the sample, a discovery he reported in the scientific literature the following year. The process he used to isolate pure chromium metal had produced a variety of vibrantly colored solutions and compounds, and it was due to this that Vauquelin’s colleagues had suggested the element be named from chroma, Greek for “color”. Vauquelin went on to detect traces of chromium in precious gems such as rubies and emeralds, and to hypothesize correctly that chromium gave these gems their brilliant colors.

The earliest uses of chromium exploited its compounds. Lead chromate, the main compound in crocoite, was used to produce a pigment called “chrome yellow”, a color well known due to its widespread use for school buses in the United States and postal vehicles in some European countries. Use of actual lead chromate has declined significantly due to toxicity concerns, but the color is still used, replicated using less toxic alternatives. Viridian, a green pigment produced from chromium(III) oxide, is not toxic and is still used widely in ceramics and glassware. Other chromium(III) compounds have been used in tanning since the early 19th century, as a reaction between chromium and the collagen fibers stabilizes leather.

Chromium compounds continue to find applications in industry. A number of chemical processes use chromium-containing catalysts including the production of polyethylene, the most common form of plastic. Chromium salts are used in wood preservatives, and chromium provides color to synthetic rubies and emeralds. The first laser was built using a synthetic ruby. Both chromite and chromium(III) oxide can withstand high temperatures, and are frequently used as refractory materials such as brick molds and foundry sands. Chromium (IV) oxide is magnetic, and is used to manufacture the magnetic tape used in audio cassettes.

The vast majority of chromium is used in metalworking , either as a component of alloys or in various types of surface treatments. Chromium strengthens and imparts corrosion resistance to alloys. High-speed tool steels include small percentages of chromium for added strength, while higher percentages of chromium produce stainless steel. Additionally, nickel-based superalloys derive increased strength from the inclusion of chromium; these alloys are frequently found in devices such as jet engines that require materials to be stable and strong at very high temperatures. Chromium can be applied to metal surfaces via electroplating, and such surface treatments can provide wear resistance and, because chromium can be polished to an appealing silvery sheen, decoration. Additionally, chromic acid is used in chromate conversion coating, which produces a distinctive yellow finish on metal surfaces that may be used for corrosion inhibition or as a primer for further coatings. Anodization of aluminum is yet another finishing process that utilizes chromic acid, though it does not produce a chromium-containing coating.

Unfortunately, chromium(VI), known commonly as hexavalent chromium, is now known to be a potent carcinogen. Hexavalent chromium ions wreak havoc in the body because they are strong oxidizing agents that are easily transported into cells, where they cause significant damage to DNA and proteins. Many industrial processes that involve chromium, including chrome plating and chromium conversion coating, usually use hexavalent forms of chromium, and therefore the contamination of groundwater with hexavalent chromium from industrial waste is a major environmental problem. Alternative processes using trivalent chromium, which does not present the same toxicity concerns, are under investigation, as use and disposal of hexavalent chromium is now highly regulated.

Chromium is mined as chromite, an iron chromium oxide mineral. This ore can be processed either to pure chromium metal or to ferrochrome, an iron-chrome alloy used primarily in the production of stainless steel. Chromium can also be recovered from scrap, and recycled metal accounts for almost a third of chromium used annually.


Sputtering Targets
+ Open All
- Close All

High Purity (99.999%) Chromium Oxide (Cr2O3) Powder Chromium's hardness and high resistance to corrosion make it ideal for alloying and steel producing applications. Steel can be made highly resistant to corrosion and discoloration by the addition of chromium, forming stainless steel. High Purity (99.99%) Chromium (Cr) Sputtering TargetWhen chromium is added to glass or ceramic glazes, it produces a brilliant green color. Chromium is available as metal and compounds with purities from 99% to 99.999% (ACS grade to ultra-high purity). Elemental or metallic forms include pellets, rod, wire and granules for evaporation source material purposes. Chromium nanoparticles and nanopowders are also available. Chromium oxides are available in powder and dense pellet form for such uses as optical coating and thin film applications. Oxides tend to be insoluble. Chromium fluoride is another insoluble form for uses in which oxygen is undesirable such as metallurgy, chemical and physical vapor deposition and in some optical coatings. Chromium is also available in soluble forms including chlorides, nitrates and acetates. These compounds can be manufactured as solutions at specified stoichiometries.

Chromium Properties

Chromium(Cr) atomic and molecular weight, atomic number and elemental symbolChromium is a Block D, Group 6, Period 4 element. Chromium Bohr ModelThe number of electrons in each of Chromium's shells is 2, 8, 13, 1 and its electron configuration is [Ar] 3d5 4s1. The chromium atom has a radius of and its Van der Waals radius is In its elemental form, CAS 7440-47-3, Elemental Chromiumchromium has a lustrous steel-gray appearance. Chromium is the hardest metal element in the periodic table. The most common source of chromium is chromite ore (FeCr2O4). Chromium was first discovered by Louis Nicolas Vauquelin in 1797. Due to its various colorful compounds, chromium was named after the Greek word 'chroma' meaning color.

Symbol: Cr
Atomic Number: 24
Atomic Weight: 51.9961
Element Category: transition metal
Group, Period, Block: 6, 4, d
Color: silvery metallic/ silver-gray
Other Names: Chrom, Cromo, Krom, Crômio
Melting Point: 1907 °C, 3465 °F, 2180 K
Boiling Point: 2671 °C, 4840 °F, 2944 K
Density: 7.19 g/cm3; @ 20 °C
Liquid Density @ Melting Point: 6.3 g/cm3
Density @ 20°C: 7.19 g/cm3
Density of Solid: 7140 kg·m3
Specific Heat: 0.46 kJ/kg/K
Superconductivity Temperature: N/A
Triple Point: N/A
Critical Point: N/A
Heat of Fusion (kJ·mol-1): 15.3
Heat of Vaporization (kJ·mol-1): 341.8
Heat of Atomization (kJ·mol-1): 394.51
Thermal Conductivity: 93.9 W·m-1·K-1
Thermal Expansion: (25 °C) 4.9 µm·m-1·K-1
Electrical Resistivity: (20 °C) 125 nΩ·m
Tensile Strength: 282 MPa
Molar Heat Capacity: 23.35 J·mol-1·K-1
Young's Modulus: 279 GPa
Shear Modulus: 115 GPa
Bulk Modulus: 160 GPa
Poisson Ratio: 0.21
Mohs Hardness: 8.5
Vickers Hardness: 1060 MN m-2
Brinell Hardness: 1120 MN m-2
Speed of Sound: (20 °C) 5940 m·s-1
Pauling Electronegativity: 1.66
Sanderson Electronegativity: 1.66
Allred Rochow Electronegativity: 1.56
Mulliken-Jaffe Electronegativity: N/A
Allen Electronegativity: N/A
Pauling Electropositivity: 2.34
Reflectivity (%): N/A
Refractive Index: N/A
Electrons: 24
Protons: 24
Neutrons: 28
Electron Configuration: [Ar] 3d5 4s1
Atomic Radius: 128 pm
Atomic Radius,
non-bonded (Å):
Covalent Radius: 139±5 pm
Covalent Radius (Å): 1.3
Van der Waals Radius: 200 pm
Oxidation States: 6, 5, 4, 3, 2, 1, -1, -2 (strongly acidic oxide)
Phase: Solid
Crystal Structure: body-centered cubic
Magnetic Ordering: AFM
Electron Affinity (kJ·mol-1) 64.237
1st Ionization Energy: 652.87 kJ·mol-1
2nd Ionization Energy: 1590.64 kJ·mol-1
3rd Ionization Energy: 2987.21 kJ·mol-1
CAS Number: 7440-47-3
EC Number: 231-157-5
MDL Number: MFCD00010944
Beilstein Number: N/A
SMILES Identifier: [Cr]
InChI Identifier: InChI=1S/Cr
PubChem CID: 23976
ChemSpider ID: 22412
Earth - Total: 4120 ppm
Mercury - Total: 7180 ppm
Venus - Total: 4060 ppm 
Earth - Seawater (Oceans), ppb by weight: 0.6
Earth - Seawater (Oceans), ppb by atoms: 0.071
Earth -  Crust (Crustal Rocks), ppb by weight: 140000
Earth -  Crust (Crustal Rocks), ppb by atoms: 55000
Sun - Total, ppb by weight: 20000
Sun - Total, ppb by atoms: 400
Stream, ppb by weight: 1
Stream, ppb by atoms: 0.02
Meterorite (Carbonaceous), ppb by weight: 3100000
Meterorite (Carbonaceous), ppb by atoms: 1200000
Typical Human Body, ppb by weight: 30
Typical Human Body, ppb by atom: 4
Universe, ppb by weight: 15000
Universe, ppb by atom: 400
Discovered By: Louis Nicolas Vauquelin
Discovery Date: 1797
First Isolation: Louis Nicolas Vauquelin (1798)

Health, Safety & Transportation Information for Chromium

Although chromium metal is an essential trace element, hexavalent chromium (Cr(VI)) is especially toxic and carcinogenic to humans. Safety data for Chromium 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) Chromium.

Safety Data
Signal Word Warning
Hazard Statements H400
Hazard Codes N/A
Risk Codes N/A
Safety Precautions N/A
RTECS Number GB4200000
Transport Information N/A
WGK Germany N/A
Globally Harmonized System of
Classification and Labelling (GHS)
Environment-Hazardous to the aquatic environment
Review and Print SDS for Chromium Metal


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


Product Name: Chromium Metal

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

CAS #: 7440-47-3

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
Not applicable.
Not applicable.


Chemical characterization: Substances
CAS# Description:
7440-47-3 Chromium
Identification number(s):
EC number: 231-157-5


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 Water
Special hazards arising from the substance or mixture
In case of fire, the following can be released:
Toxic metal oxide fume
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.
Methods and material for containment and cleaning up: Pick up mechanically.
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:
7440-47-3 Chromium (100.0%)
PEL (USA) Long-term value: 1* 0.5** mg/m³
*metal;**inorganic compds., as Cr
REL (USA) Long-term value: 0.5* mg/m³
* Cr;See Pocket Guide App. C
TLV (USA) Long-term value: 0.5 mg/m³
EL (Canada) Short-term value: C 0.1*** ppm
Long-term value: 0.5* 0.01** 0.025*** mg/m³
IARC1,ACGIH A1;*metal, i
EV (Canada) Long-term value: 0.05 mg/m³
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: Grey
Odor: Odorless
Odor threshold: Not determined.
pH-value: Not applicable.
Change in condition
Melting point/Melting range: 1907 °C (3465 °F)
Boiling point/Boiling range: 2671 °C (4840 °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): 7.19 g/cm³ (60.001 lbs/gal)
Bulk density at 20 °C (68 °F): 3300 kg/m³
Relative density
Not determined.
Vapor density
Not applicable.
Evaporation rate
Not applicable.
Solubility in / Miscibility with Water: Insoluble
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:
Toxic metal oxide fume


Information on toxicological effects
Acute toxicity:
The Registry of Toxic Effects of Chemical Substances (RTECS) contains acute toxicity data for components in this product.
LD/LC50 values that are relevant for classification:
No data
Skin irritation or corrosion:
Generally the product does not irritate the skin.
Eye irritation or corrosion:
May cause irritation
No sensitizing effects known.
Germ cell mutagenicity:
The Registry of Toxic Effects of Chemical Substances (RTECS) contains mutation data for this substance.
IARC-3: Not classifiable as to carcinogenicity to humans.
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.
(inhalation) EPA-A: human carcinogen: sufficient evidence from epidemiologic studies to support a causal association between exposure and cancer.
(inhalation) EPA-K: Known human carcinogens.
(oral) EPA-D: Not classifiable as to human carcinogenicity: inadequate human and animal
evidence of carcinogenicity or no data are available.
(oral) EPA-CBD: Carginogenic potential cannot be determined.
The Registry of Toxic Effects of Chemical Substances (RTECS) contains tumorigenic and/or carcinogenic and/or neoplastic data for this substance.
Reproductive toxicity:
The Registry of Toxic Effects of Chemical Substances (RTECS) contains reproductive data for this substance.
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
Not applicable.
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):


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)
7440-47-3 Chromium
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.

Chromium Isotopes

Naturally occurring chromium (Cr) has four stable isotopes; 50Cr, 52Cr, 53Cr, and 54Cr. 52Cr is the most abundant (83.79%). 50Cr decays by ß+ß+ to 50Ti with a half-life of (more than) 1.8x1017 years.

Nuclide Isotopic Mass Half-Life Mode of Decay Nuclear Spin Magnetic Moment Binding Energy (MeV) Natural Abundance
(% by atom)
42Cr 42.00643(32)# 14(3) ms [13(+4-2) ms] ß+ to 42V; ß+ + 2p to 40Ti (3/2+) N/A 306.79 -
43Cr 42.99771(24)# 21.6(7) ms ß+ to 43V; ß+ + p to 42Ti; ß+ + 2p to 41Sc; ß+ + a to 39Sc 0+ N/A 323.25 -
44Cr 43.98555(5)# 54(4) ms [53(+4-3) ms] ß+ to 44V; ß+ + p to 43Ti 7/2-# N/A 342.51 -
45Cr 44.97964(54) 50(6) ms ß+ to 45V; ß+ + p to 44Ti 0+ N/A 356.18 -
46Cr 45.968359(21) 0.26(6) s ß+ to 46V 3/2- N/A 374.5 -
47Cr 46.962900(15) 500(15) ms ß+ to 47V 0+ N/A 388.17 -
48Cr 47.954032(8) 21.56(3) h EC to 48V 5/2- N/A 403.7 -
49Cr 48.9513357(26) 42.3(1) min EC to 49V 0+ 0.476 414.58 -
50Cr 49.9460442(11) Observationally Stable - 7/2- N/A 403.7 4.345
51Cr 50.9447674(11) 27.7025(24) d EC to 51V 0+ -0.934 414.58 -
52Cr 51.9405075(8) STABLE - 3/2- N/A 427.31 83.789
53Cr 52.9406494(8) STABLE - 0+ -0.47454 437.26 9.501
54Cr 53.9388804(8) STABLE - 3/2- N/A 449.06 2.365
55Cr 54.9408397(8) 3.497(3) min ß- to 55Mn 0+ N/A 457.14 -
56Cr 55.9406531(20) 5.94(10) min ß- to 56Mn (3/2-) N/A 467.08 -
57Cr 56.943613(2) 21.1(10) s ß- to 57Mn 0+ N/A 486.66 -
58Cr 57.94435(22) 7.0(3) s ß- to 58Mn 5/2-# N/A 493.81 -
59Cr 58.94859(26) 460(50) ms ß- to 59Mn 0+ N/A 498.16 -
60Cr 59.95008(23) 560(60) ms ß- to 60Mn 5/2-# N/A 504.37 -
61Cr 60.95472(27) 261(15) ms ß- to 61Mn; ß- + n to 60Mn 0+ N/A 508.73 -
62Cr 61.95661(36) 199(9) ms ß- to 62Mn; ß- + n to 61Mn (1/2-)# N/A 514.94 -
63Cr 62.96186(32)# 129(2) ms ß- to 63Mn; ß- + n to 62Mn 0+ N/A 518.36 -
64Cr 63.96441(43)# 43(1) ms ß- to 64Mn (1/2-)# N/A 523.65 -
65Cr 64.97016(54)# 27(3) ms ß- to 65Mn 0+ N/A 526.14 -
66Cr 65.97338(64)# 10(6) ms ß- to 66Mn 1/2-# N/A 531.42 -
67Cr 66.97955(75)# 10# ms [>300 ns] ß- to 67Mn 1/2 N/A 533.91 -