Chromium, Physical and Chemical Properties
Chromium is a metallic element in the first transition series, Group IVB (6).
General Chromium Chemistry and Biochemistry
Chromium (Cr, atomic weight, 51.996; atomic number, 24) is an abundant metallic element usually found associated with iron-containing minerals and ores; chromite (FeCr2O4) is the most important source. The name “chromium” is derived from the Greek, χρώμα (color), referring to the intense coloration of many Cr compounds, such as PbCrO4 (crocoite), a yellow pigment. Cr metal resists corrosion due to the formation of an oxide layer that passivates its surface (cf. aluminum). Cr metal is used in iron and stainless steel alloys for its hardening and anticorrosion properties; it is also used to electroplate surfaces.
Cr belongs to the first transition series, possesses an [Ar] 3d5 4s1electronic configuration, and can form compounds in every oxidation state from −2 to +6. The biologically important oxidation states include...