Frazier,+Eric

 The Element Cadmium


 * Atomic Number: ** 48
 * Atomic Weight: ** 112.411
 * Melting Point: ** 594.22 K (321.07°C or 609.93°F)
 * Boiling Point: ** 1040 K (767°C or 1413°F)
 * Density: ** 8.69 grams per cubic centimeter
 * Phase at Room Temperature: ** Solid
 * Element Classification: ** Metal
 * Period Number: **<span style="color: black; font-family: 'Times New Roman','serif'; font-size: 16pt; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 'Times New Roman';"> 5 **Group Number:** 12 **Group Name:** none

** History and Uses: ** ** Hydrated cadmium sulfate (3CdSO **** 4 ·5H **** 2 O), one of cadmium's compounds, is used in a device called a Weston cell, a type of battery that produces a precise voltage used to calibrate medical and laboratory equipment. Cadmium sulfide (CdS), another cadmium compound, is a yellow powder that is used as a pigment. Other cadmium compounds are used in the phosphors of black and white television sets and in the blue and green phosphors in color television sets. **
 * Friedrich Strohmeyer, a German chemist, discovered cadmium in 1817 while studying samples of calamine (ZnCO **** 3 ). 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. **
 * Cadmium is a poisonous metal and its use is somewhat limited for this reason. Like zinc, cadmium can be electroplated to other materials to protect them from corrosion. Cadmium easily absorbs [|neutrons] and is used to make control rods for nuclear reactors. Cadmium is also used in rechargeable [|nickel] -cadmium batteries. **
 * Cadmium is alloyed with [|silver] to form solder, a metal with a relatively low melting point used to join electrical components, pipes and other metallic items. Cadmium based solders must be handled with care to prevent cadmium poisoning. Cadmium alloys are also used to make low friction bearings that are highly resistant to fatigue. **

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. **//__CADMIUM APPLICATIONS__//**

Cadmium is intentionally added to six major classes of products where it imparts distinct performance advantages and is present as an impurity in five major classes of products where its presence is regarded as an environmental disadvantage but which generally does not affect the performance of the product. The major intentional uses of cadmium are Ni-Cd batteries, cadmium pigments, cadmium stabilisers, cadmium coatings, cadmium alloys and cadmium electronic compounds such as cadmium telluride (CdTe). The major classes of products where cadmium is present as an impurity are non-ferrous metals (zinc, lead and copper), iron and steel, fossil fuels (coal, oil, gas, peat and wood), cement, and phosphate fertilisers (Cook and Morrow 1995).