Cadmium and its congeners are not always considered transition metals, in that they do not have partly filled d or f electron shells in the elemental or common oxidation states. Chemical properties Īlthough cadmium usually has an oxidation state of +2, it also exists in the +1 state.
As a bulk metal, cadmium is insoluble in water and is not flammable however, in its powdered form it may burn and release toxic fumes. Unlike most other metals, cadmium is resistant to corrosion and is used as a protective plate on other metals. It is similar in many respects to zinc but forms complex compounds. One of its few new uses is in cadmium telluride solar panels.Īlthough cadmium has no known biological function in higher organisms, a cadmium-dependent carbonic anhydrase has been found in marine diatoms.Ĭharacteristics Physical properties Ĭadmium is a soft, malleable, ductile, silvery-white divalent metal. Cadmium use is generally decreasing because it is toxic (it is specifically listed in the European Restriction of Hazardous Substances Directive ) and nickel-cadmium batteries have been replaced with nickel-metal hydride and lithium-ion batteries. Cadmium was used for a long time as a corrosion-resistant plating on steel, and cadmium compounds are used as red, orange, and yellow pigments, to color glass, and to stabilize plastic. It was discovered in 1817 simultaneously by Stromeyer and Hermann, both in Germany, as an impurity in zinc carbonate.Ĭadmium occurs as a minor component in most zinc ores and is a byproduct of zinc production. The average concentration of cadmium in Earth's crust is between 0.1 and 0.5 parts per million (ppm).
Cadmium and its congeners in group 12 are often not considered transition metals, in that they do not have partly filled d or f electron shells in the elemental or common oxidation states. Like zinc, it demonstrates oxidation state +2 in most of its compounds, and like mercury, it has a lower melting point than the transition metals in groups 3 through 11.
This soft, silvery-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Cadmium is a chemical element with the symbol Cd and atomic number 48.
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