Revision 8 for 'Chromium'

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Chromium (chemical symbol Cr) is one of the trace elements, and is required for the normal functioning of several enzymes, and is also important in glucose homeostasis.


Basic chemistry

Chromium has the atomic number 24 with an atomic weight of 51.9961 g/mol. Like iron, it is one of the transition metals. It exists in multiple oxidation states, but physiologically the trivalent (3+) state is the most important. 


In nature, chromium exists as three stable isotopes: 52Cr, 53Cr and 54Cr. 52Cr is the commonest on Earth, accounting for 83.8% of the total. In total an additional 19 unstable isotopes are known, ranging from the stablest, 50Cr with a half life of 1.8 × 1017 years, and 51Cr with a half-life of 27.7 days, and the rest with half lives all shorter than a day. Several decaying in seconds only.



Biological function

Its importance in normal human physiology is contentious.

History and etymology

In 1761, Johann Gottlob Lehmann (1719–1767) 2, a German geologist, discovered the mineral crocoite in the Urals, which is now known to be lead chromate. 

Louis-Nicolas Vauquelin (1763–1829) 2, a French chemist, produced chromium (III) oxide from crocoite in 1797. The following year he extracted impure chromium from reducing chromium (III) oxide with charcoal in 1798.

Chromium originates from the Ancient Greek word, χρώμα (chroma), which means color.

Related pathology

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