Facts about Chromium
Deposits of native chromium metal are rare, but they have been discovered.
Writing in the journal Science, Tailuan Nguyen, a graduate student working with Philip Power of the University of California, Davis, describes the synthesis of a compound of chromium(I) and a hydrocarbon radical.
Chromium (chemical symbol Cr, atomic number 24) is a hard, shiny, steel-gray metal that takes a high polish and does not tarnish.
Chronic exposure to chromium (VI) compounds can cause permanent eye injury unless properly treated.
The lethal dose of poisonous chromium (VI) compounds is about one-half teaspoon of material.
Chromium isotopic contents in the earth are typically combined with manganese (Mn) isotopic contents and have found application in isotope geology.
Chromium and its compounds have a variety of applications, some of which are noted below.
Chromium is a transition metal in period four of the periodic table, situated between vanadium and manganese.
Various chromium compounds, such as chromium(III) oxide and lead chromate, are brightly colored and used in paints and pigments.
Chromium is highly likely to induce sensitization leading to dermatitis, especially of the hand and forearms, which is chronic and difficult to treat.
Now its primary use is for metal alloys, accounting for 85 percent of the use of chromium.
Primer paint containing hexavalent chromium is still widely used for aerospace and automobile refinishing applications.
Potassium dichromate is one of the most common culprits in causing chromium dermatitis.
The isotopes of chromium range in atomic weight from 43 atomic mass units (amu) (43Cr) to 67 amu (67Cr).
Chromium metal and chromium(III) compounds are not usually considered health hazards, but hexavalent chromium (chromium VI) compounds can be toxic if orally ingested or inhaled.
Naturally occurring chromium is composed of three stable isotopes: 52Cr, 53Cr, and 54Cr.
Chromium currently remains the only element for which quintuple bonds have been observed.
Chromium trioxide, CrO3, the acid anhydride of chromic acid, is sold industrially as "chromic acid."
Most chromium (VI) compounds are irritating to the eyes, skin, and mucous membranes.
In 1798, Vauquelin discovered that he could isolate metallic chromium by heating the oxide in a charcoal oven.
Chromium was named after the Greek word "chroma" meaning color, because of the many colorful compounds made from it.
Chromium(III) oxide (Cr2O3) also known as chromium sesquioxide or chromia, is one of four oxides of chromium.
The human body needs trace amounts of trivalent chromium (chromium(III)) for sugar metabolism, but hexavalent chromium (chromium(VI)) is very toxic.
Trivalent chromium (Cr(III) or Cr3+) is required in trace amounts for sugar metabolism in humans, and its deficiency can cause chromium deficiency.
In 1797, Nicolas-Louis Vauquelin received samples of crocoite ore. By mixing crocoite with hydrochloric acid, he was able to produce chromium oxide, with the chemical formula CrO3.
According to recommendations by the World Health Organization, the maximum allowable concentration of chromium (VI) in drinking water is 0.05 milligrams per liter.