Cadmium

Cadmium
An Internet Hotlist on Cadmium

created by chloereid09
The Stoneleigh-Burnham School

Introduction

Image from http://www.neyco.fr/images/10_8_base_cadmium.jpg
Cadmium is an incredibly complex and unique element. Here is some basic information on cadmium.

Atomic number: 48

Atomic mass: 112

Physical characteristics: Pure cadmium, the metal, is a soft silver white color. Cadmium is most often found combined with other elements, which produces compounds such as Cadmium chloride, Cadmium oxide, and Cadmium sulfite.

Chemical properties: Cadmium and its compounds are stable. In water some of the compounds will be quite soluble and others will be insoluble. As fine powder cadmium metal will burn, releasing toxic fumes of cadmium oxide.

Toxicity: Cadmium is an occupational hazard associated with industrial processes such as metal plating and the production of nickel-cadmium batteries, pigments, plastics and other synthetics. The primary route of exposure in industrial settings is inhalation. Inhalation of cadmium-containing fumes can result initially in metal fume fever but may progress to chemical pneumonitis, pulmonary edema, and death.

Uses: About three-quarters of cadmium is used in batteries and most of the remaining quarter is used mainly for pigments, coatings and plating, and as stabilizers for plastics.

Production: Cadmium is a common impurity in zinc, and it is most often isolated during the production of zinc. Zinc sulfide ores are roasted in the presence of oxygen converting the zinc sulfide to the oxide. Zinc metal is produced either by smelting the oxide with carbon or by electrolysis in sulfuric acid. Cadmium is isolated from the zinc metal by vacuum distillation if the zinc is smelted, or cadmium sulfate is precipitated out of the electrolysis solution.

History: Cadmium was discovered in Germany in 1817 by Friedrich Strohmeyer. Strohmeyer found the new element within an impurity in zinc carbonate and for 100 years Germany remained the only important producer of the metal.

The Internet Resources
- Cadmium - Wikipedia was the first place I went for information on the element Cadmium, or Cd. It gave me a relatively brief, six-page overview, which was what I was looking for. It explained the notable characteristics, applications, history, occurrence, toxicity, and necessary precautions. I give this site five stars out of five stars.
- Cadmium Compounds - I became more and more specific by searching for �Cadmium compounds� and I found another Wikipedia site. This was a very general site because it had seventeen sub-pages about Cadmium and its compounds, even when I was looking to get more specific. It did, however, refer me to several other interesting links. I give this site four-and-a-half stars out of five stars.
- Cadmium Exposure - Included in this site were several very interesting statistics in Cadmium: the largest sources of airborne cadmium in the environment are the burning of fossil fuels such as coal or oil, and incineration of municipal waste materials. Cadmium may also be emitted into the air from zinc, lead, or copper smelters. For nonsmokers, food is generally the largest source of cadmium exposure. Cadmium levels in some foods can be increased by the application of phosphate fertilizers or sewage sludge to farm fields. Smoking is another important source of cadmium exposure. Smokers have about twice as much cadmium in their bodies as do nonsmokers. Because this site did not pertain directly to what I am studying, I do not give this site any stars out of five stars.
- Cadmium Sulphuratum - This site was specifically on cadmium poisoning, which can be deadly. Cadmium sulphuratum poisoning includes wanting to be perfectly quiet and desiring company but being too tired to communicate or react, as well as no or little fear of death. Symptoms include: yellow fever, cholera, one-sided paralysis and paralysis of a part or pain and formication in paralyzed parts and numbness of parts. I give this site two stars out of five stars because it did not pertain directly to my project.
- Cadmium World - This site has information on Nickel-Cadmium batteries, cadmium pigments, cadmium stabilizers, cadmium coatings, and alloys and minor uses. This site was such a good resource to have found because it is only about cadmium, and it has so much information on cadmium. It explained the isolation of cadmium, including how it is rare that preparation of cadmium in the laboratory should be required because of environmental concerns about cadmium. The isolation of cadmium is associated with zinc recovery as cadmium is an impurity in zinc ores. Most zinc production is based upon sulphide ores. These are roasted in industrial plants to form zinc oxide. This may be reduced with carbon to form zinc metal, but in practice ingenious technology is required to ensure that the resulting zinc does not contain oxide impurities. It had information on recycling cadmium and the environment, collection, and cadmium and the future. I give this site one star out of five stars.
- Cadmium and Cars - This website taught me more about what Cadmium is. Cadmium is a natural element in the earth's crust. It is usually found as a mineral combined with other elements such as oxygen (cadmium oxide), chlorine (cadmium chloride), or sulfur (cadmium sulfate, cadmium sulfide). All soils and rocks, including coal and mineral fertilizers, contain some cadmium. Most cadmium used in the United States is extracted during the production of other metals like zinc, lead, and copper. Cadmium does not corrode easily and has many uses, including batteries, pigments, metal coatings, and plastics. This site, as the title hints, is about cars and how cadmium can be used. Its pros and cons include: low galvanic corrosion in contact with aluminum: exceptional white luster similar to silver plating: corrosion resistance in marine environment: excellent lubricity: low electrical contact resistance: uniform ductile deposit: pliant: and solid rust prevention. I give this site one star out of five stars.
- Cadmium and Toxic Metals - This site taught me that Cadmium is an extremely toxic metal commonly found in industrial workplaces, particularly where any ore is being processed or smelted. Due to its low permissible exposure limit (PEL), overexposures may occur even in situations where trace quantities of cadmium are found in the parent ore or smelter dust. Cadmium is used extensively in electroplating, although the nature of the operation does not generally lead to overexposures. Several deaths from acute exposure have occurred among welders who have unsuspectingly welded on cadmium-containing alloys or worked with silver solders. Cadmium is also found in some industrial paints and may represent a hazard when sprayed. Operations involving removal of cadmium paints by scraping or blasting may similarly pose a significant hazard. Cadmium is also present in the manufacture of some types of batteries. Cadmium emits a characteristic brown fume (CdO) upon heating, which is relatively non-irritating, and thus does not alarm the exposed individual. I give this site three stars out of three stars.
- Cadmium as a Commodity - This was a “dot gov” site as well. It was a good place to go to look for information on specifically how Cadmium is a commodity. It had several interesting statistics which I learned from. It has a very short write-up of Cadmium on the actual page, but publications and references included on the page were extensive and did such things as highlight all of the positive uses of Cadmium. I give this site four stars out of five stars.
- Chemical Element - I searched “chemical element” to find this site to get a little bit more specific. Starting so broadly made me slow down and take a breath and assess everything that I needed to do. This website taught me that a chemical element, or element, is a type of atom that is distinguished by its atomic number; that is, by the number of protons in its nucleus. The term is also used to refer to a pure chemical substance composed of atoms with the same number of protons. Also, starting with Wikipedia is something that I like to do because everything is so well organized. I give this site five stars out of five stars.
- Element - I searched “element” to find this site because I wanted to start generally and get more specific. Wikipedia is usually the first place I start because it is a collaborative website and has so much information. This site was helpful to me because it gave me a broad overview of what I needed to focus on. With this site, I got exactly what I wanted and so much more, so I give this site five stars out of five stars.
- Elements - Because this was a 'dot gov' site, I trusted it. The knowledge I found there of every element in the periodic table was extensive. It updated me on the history, cost, and handling of such dangerous elements as Cadmium. Like the Wikipedia site that I found, this gave me a broad overview of everything that I needed to know about Cadmium. I give this site four-and-a-half stars out of five stars.
- Environmental Chemistry - Environmental Chemistry was the next place that I looked. It was much like all the other sites, but less useful to me because I had already found the information that I needed. However it was up to date on health regulations and other important stats relating to cadmium. Comprehensive data on the chemical element Cadmium is provided on this page; including scores of properties, element names in many languages, and most known nuclides of Cadmium. Common chemical compounds are also provided for many elements. In addition technical terms are linked to their definitions and the menu contains links to related articles that are a great aid in studies. I give this site four stars out of five stars.
- It's Elemental - 'It's Elemental' taught me all about the history of Cadmium, and it was the first and only site I found that was only about the hisotry of the element. I learned such things as Cadmium was discovered by Friedrich Strohmeyer, a German chemist, in 1817 while studying samples of calamine (ZnCO3). When heated, Strohmeyer noticed that some samples of calamine glowed with a yellow color while other samples did not. After further examination, he determined that the calamine that changed color when heated contained trace amounts of a new element. There is only one mineral that contains significant amounts of cadmium, greenockite (CdS), but it is not common enough to mine profitably. Fortunately, small amounts of cadmium are found in zinc ores and most of the cadmium produced today is obtained as a byproduct of mining and refining zinc. I give this site one star out of five stars.
- Toxic Facts On Cadmium - This site was interesting because it was not like all of the others. It had a focus on the toxicity of Cadmium and the cancer-causing aspects of it. This fact sheet answers the most frequently asked health questions about cadmium. This fact sheet is one in a series of summaries about hazardous substances and their health effects. Because it does not pertain directly to my research project, I give this site two-and-a-half stars out of five stars.
- Web Elements - This site gave me descriptions of the element Cadmium, including name: cadmium, symbol: Cd, atomic number: 48, atomic weight: 112.411 g, group number: 12, period number: 5, block: d-block… Its standard state is solid at 298 K. Color: silvery grey metallic. Metallic Availability: cadmium is available in many forms including foil, granules, pellets, sheet, powder, rod, shot, sticks, wire and 'mossy cadmium'. Small and large samples of cadmium foil, sheet, and wire can be purchased. Because this site was so well-organized, I give this site two stars out of five stars.
Content by chloereid09, creid@sbschool.org
http://www.kn.att.com/wired/fil/pages/listcadmiumch.html
Last revised Mon Dec 17 8:20:36 US/Pacific 2007