Chemistry

An Overview about the Chemical Element Cadmium



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Cadmium is a potent poison. It has no role whatsoever in the human body and exposure to it causes cancer. We only use it in industry and art when we must, and then we must take strong precautions.

Cadmium, symbol Cd, has an atomic number of 48, meaning there are 48 protons in its nucleus. This places it in the zinc family, which used to be called IIB, and it is usually found in small quantities in combination with zinc ore. China produces the largest share of mined cadmium.

Its standard atomic weight is 112.411. Atomic weight is an average of the weights of all the isotopes of an element in the earth's crust and atmosphere, weighted according to their occurrence in nature. An isotope is a species of an element that has the same number of protons, 48 in the case of cadmium, but a varying number of neutrons, which give it a different atomic weight. There appear to be eight naturally occurring isotopes of cadmium. Purified, cadmium appears as a soft silvery metallic element which is easily cut with a knife.

Three quarters of the cadmium supply goes into batteries, the well-known NiCd (nickel-cadmium) types. These are rechargeable; a great advantage for decreasing the production of waste. They also weigh less than other batteries, for the amount of energy they produce, and recharge quickly and efficiently. They are more expensive than disposable batteries. However, the great disadvantage of these batteries is the cadmium they add to the environment if they are incinerated or added to landfill. It is essential that NiCd batteries be properly recycled.

Almost all the rest of cadmium in commerce goes for paints, pigments and coatings. So it is important in architecture, decoration, and the arts. Potters grind cadmium compounds, carefully, to add to their glazes, and it is found in the best and brightest red and yellow pigments for oil painters. It's in other types of paint too, and in silver solder. Artists should use extreme care that cadmium is not inhaled or absorbed through the skin.

Some cadmium is used in plastics, and cadmium rods can be used in nuclear power plants to absorb neutrons and slow or stop nuclear reactions. It's also useful in some semi-conductors, such as solar cells.

One route of exposure to cadmium, which causes kidney diseases and pulmonary edema as well as many kinds of cancer, is through industrial, on-the-job, contact. Yet society is now well aware of the dangers of cadmium, so these pathways are well policed. Consequently, the most common way for modern citizens to be exposed to cadmium is through cigarette smoking. Smokers are believed to have twice the amount of deadly cadmium in their bodies as non-smokers. Yet another good reason to stop.



http://www.epa.gov/ttn/atw/hlthef/cadmium.html
http://www.webelements.com/cadmium/
http://www.webelements.com/periodicity/atomic_weight/#footnote_g
http://www.hardwaresecrets.com/article/292
http://findarticles.com/p/articles/mi_m1200/is_n11_v138/ai_8936190
http://www.buzzle.com/articles/the-worlds-first-nuclear-reactor.html

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