48Cd Cadmium

Year Discovered

1817

Discovered By

Friedrich Stromeyer of Germany

Biological Rating

Not necessary for life.

Description

Named from the Greek word meaning “calamine”, cadmium is a soft, bluish-white metal. It is soft enough to be cut with a knife. It is an active metal, reacting with air and acids. Cadmium is used in low-melting alloys, especially solder. It is also used in electroplating, paint pigments (cadmium sulfide is the common pigment cadmium yellow) and rechargeable batteries (ni-cads). Cadmium absorbs neutrons and is used in the control rods that dampen nuclear reactions in fission reactors. Cadmium compounds are used in black and white television tubes and in the blue and green phosphors in color television tubes. Due to the toxicity, cadmium is being phased out wherever possible.

Biological Benefits

Cadmium is believed to be a required trace element, although its need and use are not currently understood. It is thought to be involved with metabolism.

Role in Life Processes

No known benefits for life processes.

Percentage Amount in the Human Body: 0.00007%

Sources

Cadmium minerals are very rare and include cadmoselite (cadmium selinide), greenockite (cadmium sulfide) and otavite (cadmium carbonate). Cadmium substitutes for zinc in sphalerite, so most is recovered during the processing of zinc ores. It is produced in most zinc-smelting countries of the world.