chorim
thin rod
5940 m/s (at 20 °C)
Thermal expansion
4.9 µm/(m⋅K) (at 25 °C)
Thermal conductivity
93.9 W/(m⋅K)
Electrical resistivity
125 nΩ⋅m (at 20 °C)
Magnetic ordering
antiferromagnetic (rather: SDW)[2]
Molar magnetic susceptibility
+280.0×10−6 cm3/mol (273 K)[3]
Young's modulus
279 GPa
Shear modulus
115 GPa
Bulk modulus
160 GPa
Poisson ratio
0.21
Mohs hardness
8.5
Vickers hardness
1060 MPa
Brinell hardness
687–6500 MPa
CAS Number
7440-47-3
History
Discovery and first isolation
Louis Nicolas Vauquelin (1794, 1797)
Isotopes of chromiumve
Main isotopes[4] Decay
abundance half-life (t1/2) mode product
50Cr 4.34% stable
51Cr synth 27.7025 d ε 51V
γ –
52Cr 83.8% stable
53Cr 9.50% stable
54Cr 2.37% stable
Category: Chromium
viewtalkedit | references
Chromium metal is valued for its high corrosion resistance and hardness. A major development in steel production was the discovery that steel could be made highly resistant to corrosion and discoloration by adding metallic chromium to form stainless steel. Stainless steel and chrome plating (electroplating with chromium) together comprise 85% of the commercial use. Chromium is also greatly valued as a metal that is able to be highly polished while resisting tarnishing. Polished chromium reflects almost 70% of the visible spectrum, and almost 90% of infrared light.[6] The name of the element is derived from the Greek word χρῶμα, chrōma, meaning color,[7] because many chromium compounds are intensely colored.
Industrial production of chromium proceeds from chromite ore (mostly FeCr2O4) to produce ferrochromium, an iron-chromium alloy, by means of aluminothermic or silicothermic reactions. Ferrochromium is then used to produce alloys such as stainless steel. Pure chromium metal is produced by a different process: roasting and leaching of chromite to separate it from iron, followed by reduction with carbon and then aluminium.
In the United States, trivalent chromium (Cr(III)) ion is considered an essential nutrient in humans for insulin, sugar, and lipid metabolism.[8] However, in 2014, the European Food Safety Authority, acting for the European Union, concluded that there was insufficient evidence for chromium to be recognized as essential.[9]
While chromium metal and Cr(III) ions are considered non-toxic, hexavalent chromium, Cr(VI), is toxic and carcinogenic. According to the European Chemicals Agency (ECHA), chromium trioxide that is used in industrial electroplating processes is a "substance of very high concern" (SVHC).[10]
Abandoned chromium production sites often require environmental cle
