Periodic Table

Chromium

Transition Metal

Quick Facts about Chromium

V
  • solid- state of matter at room temperature
  • Stable- has at least one stable isotope
  • +6, +3, +2- common oxidation states in compounds
  • BCC- crystal structure, atomic arrangement in solid form
Mn

Chromium (Cr) is element 24 on the periodic table. Atomic mass of Cr: 51.9960 u. Cr is in period 4, group 6. Melting point of Cr: 2180.00 K.Density of Cr: 7.15 g/cm³.

Why Chromium Matters

The element that makes stainless steel stainless and chrome shine

In Your Home

  • Stainless steel appliances and cutlery
  • Chrome-plated faucets and fixtures
  • Some leather tanning
  • Green glass bottles

Industry Uses

SteelStainless steel contains 10-30% chromium
PlatingDecorative and hard chrome plating
PigmentsChrome yellow and green pigments
AerospaceSuperalloys for jet engines

In Your Body

✓ Essential for life

Trivalent chromium (Cr3+) is essential in trace amounts for insulin function and glucose metabolism. Deficiency may affect blood sugar.

Safety: Cr3+ is essential and safe. Cr6+ (hexavalent chromium) is highly toxic and carcinogenic (Erin Brockovich case).

Discovery of Chromium

Discovered by Louis Vauquelin in France, 1797

Name origin: Greek: chrôma (color).

History & Events

1797
Discovery
Louis Nicolas Vauquelin discovered chromium in Siberian red lead ore
1913
Stainless Steel
Harry Brearley invented stainless steel in Sheffield, England
1996
Erin Brockovich Case
PG&E settled $333 million for hexavalent chromium contamination

About Chromium

Hard silvery transition element. Used in decorative electroplating. Discovered in 1797 by Vauquelin.

Atomic Properties of Cr

Atomic Number of Cr
24
Atomic Mass of Cr
51.9960 u
Electron Configuration
[Ar] 3d5 4s1
Electronegativity
1.66
Block
d-block
Group
6
Period
4

Physical Properties of Cr

Phase (STP)
solid
Melting Point of Cr
2180.00 K
Boiling Point of Cr
2944.00 K
Density of Cr
7.1500 g/cm3

Thermal Properties

Heat of Fusion
21.00 kJ/mol
Heat of Vaporization
342.00 kJ/mol
Specific Heat
0.45 J/g·K
Molar Heat Capacity
23.35 J/mol·K
Thermal Conductivity
93.90 W/m·K

Atomic Radii

Calculated
140 pm
Covalent
122 pm
Van der Waals
206 pm
Metallic
119 pm

Common Misconceptions

Wrong:All chromium is dangerous.
Correct:Only hexavalent chromium (Cr6+) is toxic. Trivalent chromium (Cr3+) in food and supplements is safe and essential.
Wrong:Chrome and chromium are different.
Correct:Chrome is just short for chromium. 'Chrome plating' means chromium plating.
Wrong:Stainless steel can't rust.
Correct:Stainless steel resists corrosion but can rust under certain conditions (low oxygen, high chloride).

Isotopes of Chromium

Chromium has 4 naturally occurring isotopes, plus 1 notable radioactive isotope.

IsotopeAtomic Mass (u)AbundanceHalf-LifeDecay Mode
5024Cr (Cr-50)Chromium-50 isotope49.946041834.345%——
5124Cr (Cr-51)Chromium-51 isotope50.94476740%27.7 daysEC
5224Cr (Cr-52)Chromium-52 isotope51.9405062383.79%——
5324Cr (Cr-53)Chromium-53 isotope52.940648159.501%——
5424Cr (Cr-54)Chromium-54 isotope53.938879162.365%——

Data source: NIH PubChem (aggregated from IUPAC, NIST)

Isotope Applications

Isotopes of Chromium have important real-world applications in science and industry.

Medical Applications

Stable isotopes of chromium are used to investigate the metabolism of chromium (III), which is an essential nutrient. Chromium stable isotopes (53Cr and 54Cr) have been administered to patients and the relative metabolic activity of each isotope is measured to study insulin function in patients suffering from diabetes (a disease in which the body is unable to produce any or enough insulin, and/or is not able to properly use the insulin that it does produce, resulting in elevated levels of glucose in the blood) [210]. 51Cr and 53Cr have been used to label red blood cells to determine blood volume and life-time of red blood cells in the body [210].

Abundance

Earth's Crust
102.0 mg/kg
Seawater
3.00×10-4 mg/L

Uses

Used to make stainless steel. It gives the color to rubies and emeralds. Iron-nickel-chromium alloys in various percentages yield an incredible variety of the most important metals in modern technology.

Sources

Chromite [Fe,Mg(CrO4)] is its most important mineral. Produced commercially by heating its ore in the presence of silicon or aluminium.

Geochemistry

Goldschmidt
litophile
Geochemical Class
first series transition metal

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