10 Chromium Facts

Facts about the Element Chromium or Cr

This is decorative chrome on a motorcycle. Chrome refers to electroplated chromium over another metal. Chrome may be either hexavalent chromium or trivalent chromium. Hexavalent chromium is extremely toxic.
This is decorative chrome on a motorcycle. Chrome refers to electroplated chromium over another metal. Chrome may be either hexavalent chromium or trivalent chromium. Hexavalent chromium is extremely toxic. Brian Stablyk / Getty Images

Here are 10 fun and interesting facts about the element chromium, a shiny blue-gray transition metal.

  1. Chromium has atomic number 24. It is the first element in Group 6 on the Periodic Table, with an atomic weight of 51.996 and density of 7.19 grams per cubic centimeter.

     

  2. Chromium is a hard, lustrous, steel-gray metal. Chromium may be highly polished. Like many transition metals, it has a high melting point (1907°C, 3465°F) and boiling point (2671°C, 4840°F).

     

  1. Stainless steel is hard and resists corrosion due to the addition of chromium.

     

  2. Chromium is the only element which shows antiferromagnetic ordering in its solid state at and below room temperature. Chromium becomes paramagnetic above 38°C. The element's magnetic properties are among its most notable characteristics.

     

  3. Trace amounts of trivalent chromium are needed for lipid and sugar metabolism. Hexavalent chromium and its compounds are extremely toxic and also carcinogenic. The +1, +4 and +5 oxidation states also occur, although they are less common.

     

  4. Chromium occurs naturally as a mix of three stable isotopes: Cr-52, Cr-53, and Cr-54. Chromium-52 is the most abundant isotope, accounting for 83.789% of its natural abundance. 19 radioisotopes have been characterized. The most stable isotope is chromium-50, which has a half life of over 1.8×1017 years.

     

  5. Chromium is used to prepare pigments (including yellow, red and green), color glass green, color rubies red and emeralds green, in some tanning processes, as a decorative and protective metal coating and as a catalyst.

     

  1. Chromium in air is passivated by oxygen, forming a protective layer that is essentially a spinel that is a few atoms thick. The coated is metal is usually called chrome.

     

  2. Chromium is the 21st or 22nd most abundant element in the Earth's crust. It is present at a concentration of approximately 100 ppm.

     

  1. Most chromium is obtained by mining the mineral chromite. Although it is rare, native chromium also exists. It may be found in kimberlite pipe, where the reducing atmosphere favors the formation of diamond in addition to elemental chromium.

Additional Chromium Facts

  • About 75-85% of the chromium that is commercially produced is used to make alloys, such as stainless steel. Most of the remaining chromium is used in the chemical industry and in foundries and refractories.
  • Chromium was discovered by French chemist Nicolas Louis Vauquelin in 1797 from a sample of the mineral crocoite (lead chromate). He reacted chromium trioxide (Cr2O3) with charcoal (carbon), which yield needle-like crystals of chromium metal. Although it wasn't purified until the 18th century, people had been using chromium compounds for thousands of years. The Qin Dynasty of China used chromium oxide on their weapons. Although it's unclear whether they sought the color of the compounds or the properties, the metal did protect the weapons from degradation.
  • The name of the element comes from the Greek word chroma, which translates as "color". The name "chromium" was proposed by French chemists Antoine Francis de Fourcoy and René-Just Haüy. This reflects the colorful nature of chromium compounds and the popularity of its pigments, which may be found in yellow, orange, green, purple, and black. The color of a compound may be used to predict the oxidation state of the metal.