New scientific results confirm an anomaly seen in previous experiments, which may point to an as-yet-unconfirmed new elementary particle, the sterile neutrino, or indicate the need for a new interpretation of an aspect of ...
General Physics
Jun 16, 2022
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3328
Rusted iron pipes can react with residual disinfectants in drinking water distribution systems to produce carcinogenic hexavalent chromium in drinking water, reports a study by engineers at UC Riverside.
Environment
Dec 3, 2020
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3536
Researchers find calcium outshines chromium in the catalytic production of ammonia. Working together, a humble trio of calcium atoms have defied expectations to break apart one of the strongest chemical bonds known. The atoms ...
Materials Science
Aug 10, 2023
1
14
Chromium steel—similar to what we know today as tool steel—was first made in Persia, nearly a millennium earlier than experts previously thought, according to a new study led by UCL researchers.
Archaeology
Sep 23, 2020
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2127
The chrome plating on the Terracotta Army bronze weapons—once thought to be the earliest form of anti-rust technology—derives from a decorative varnish rather than a preservation technique, finds a new study co-led by ...
Archaeology
Apr 4, 2019
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1000
(Phys.org) —Geologists are letting the air out of a nagging mystery about the development of animal life on Earth.
Earth Sciences
Oct 31, 2014
97
1
(Phys.org) -- University at Buffalo researchers are making significant progress on rust-proofing steel using a graphene-based composite that could serve as a nontoxic alternative to coatings that contain hexavalent chromium, ...
Nanomaterials
May 18, 2012
2
0
Found in jewelry, car parts, pigments, and industrial chemical reactions, the metal chromium and its compounds are often employed for their color, finish, and anti-corrosive and catalytic properties. Currently, geoscientists ...
Earth Sciences
Apr 6, 2021
0
704
The water crisis in Flint, Michigan, brought much-needed attention to the problem of potentially toxic metals being released from drinking water distribution pipes when water chemistry changes. Now, researchers reporting ...
Environment
Sep 30, 2020
2
276
(Phys.org) —Two French researchers, Guilhem Larrieu and Xiang‑Lei Han, may have succeeded in possibly setting back the date to which Moore's Law would no longer apply by creating a new kind of nanowire Field-Effect Transistor ...
Chromium ( /ˈkroʊmiəm/ kroh-mee-əm) is a chemical element which has the symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point. It is also odorless, tasteless, and malleable. The name of the element is derived from the Greek word "chrōma" (χρώμα), meaning colour, because many of its compounds are intensely coloured. Chromium oxide was used by the Chinese in the Qin dynasty over 2,000 years ago to coat weapons such as bronze crossbow bolts and steel swords found at the Terracotta Army. It later came to the attention of the west when it was discovered by Louis Nicolas Vauquelin in the mineral crocoite (lead(II) chromate) in 1797. Crocoite was used as a pigment, and after the discovery that the mineral chromite also contains chromium, this latter mineral was used to produce pigments as well.
Chromium was regarded with great interest because of its high corrosion resistance and hardness. A major development was the discovery that steel could be made highly resistant to corrosion and discoloration by adding chromium to form stainless steel. This application, along with chrome plating (electroplating with chromium) are currently the highest-volume uses of the metal. Chromium and ferrochromium are produced from the single commercially viable ore, chromite, by silicothermic or aluminothermic reaction or by roasting and leaching processes.
Although trivalent chromium (Cr(III)) is required in trace amounts for sugar and lipid metabolism, few cases have been reported where its complete removal from the diet has caused chromium deficiency. In larger amounts and different forms chromium can be toxic and carcinogenic. The most prominent example of toxic chromium is hexavalent chromium (Cr(VI)). Abandoned chromium production sites often require environmental cleanup.
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