Information AboutMagnesium |
|
Magnesium is the Chemical Element in the Periodic Table that has the symbol '''Mg''' and Atomic Number 12 and an Atomic Mass of 24.31. Magnesium is the eighth most abundant element and constitutes about 2% of the Earth 's Crust by weight, and it is the third most plentiful element dissolved in Seawater . This Alkaline Earth Metal is primarily used as an Alloy ing agent to make Aluminium -magnesium alloys, sometimes called "magnalium" or "magnelium". NOTABLE CHARACTERISTICS Magnesium is a fairly strong, silvery-white, light-weight metal (one third lighter than Aluminium ) that slightly Tarnish es when exposed to air, although unlike the alkaline metals, storage in an oxygen free environment is unnecessary. Magnesium is difficult to ignite in mass or bulk, though it is easy to light if it is shaved into thin strips. Once ignited, it is difficult to extinguish, being able to burn in both Nitrogen (forming magnesium nitride), and Carbon Dioxide (forming magnesium oxide and Carbon ). Magnesium, when it burns in air, produces a brilliant white light. This was used in the early days of Photography when magnesium powder was used as a source of illumination (flash powder). Later, magnesium ribbon was used in electrically ignited flash bulbs. Magnesium powder is still used in the manufacture of Fireworks and marine Flare s where a brilliant white light is required. APPLICATIONS Magnesium is the third most commonly used structural metal, following steel and aluminum. Magnesium compounds, primarily Magnesium Oxide , are used mainly as Refractory material in Furnace linings for producing Iron , Steel , nonferrous metals, Glass , and Cement . Magnesium oxide and other compounds also are used in agricultural, chemical, and construction industries. As a metal, this element's principal use is as an alloying additive to Aluminium with these aluminium-magnesium alloys being used mainly for Beverage Can s. Magnesium, in its purest form, can be compared to aluminium, and is strong and light, so it is used in several high volume part manufacturing applications, including automotive and truck components. Specialty, high-grade car wheels of magnesium alloy are called " Mag Wheels ." In 1957, a Corvette SS, designed for racing, was constructed, with completely magnesium body panels. Volkswagen has used magnesium in its engine components for many years. For a long time, Porsche used magnesium alloy for its Engine Block s due to the weight advantage. However, there is renewed interest in magnesium engine blocks, as featured in the 2006 BMW 325i and 330i models. The award-winning BMW engine uses an aluminium alloy insert for the cylinder walls and cooling jackets surrounded by a high temperature magnesium alloy AJ62A. The application of magnesium AE44 alloy in the 2006 Corvette Z06 engine cradle has advanced the technology of designing robust automotive parts in magnesium. Both of these alloys are recent developments in high temperature low creep magnesium alloys. New alloy development and lower costs, which are becoming competitive to aluminium, will further the number of automotive applications. In December 2005, for the first time on record, the automotive grade magnesium alloy price per cm3 dropped below the A380 aluminum alloy price per cm3. The second application field of magnesium is electronic devices. Due to low weight, good mechanical and electrical properties, magnesium is widely used for manufacturing of mobile phones, laptops, cameras, etc. housings and other electronic components. Historicaly, magnesium was one of the main aerospace construction metals. However, due to low corrosion resistance, the application of magnesium in aerospace industry was significantly reduced in 60-70th years of last century. At the present time, magnesium stays on good way to return to be aerospace metal. European Community runs three R&D magnesium projects in Aerospace priority of Six Framework Program. Other uses include:
HISTORY The name originates from the Greek word for a district in Thessaly called Magnesia . Joseph Black in England recognized magnesium as being an element in 1755 , Sir Humphry Davy electrolytically isolated pure magnesium metal in 1808 from a mix of magnesia and Hg O , and A. A. B. Bussy prepared it in coherent form in 1831 . Magnesium is the eighth most abundant element in the earth's crust. It is an Alkaline Earth Metal and therefore does not occur uncombined with other elements. It is found in large deposits of Magnesite , Dolomite , and other Mineral s. Because it is hard to extinguish, it guessed that it was used in Greek Fire . SOURCES Although magnesium is found in over 60 Mineral s, only Dolomite , Magnesite , Brucite , Carnallite , Talc , and Olivine are of commercial importance. In the United States this metal is principally obtained by Electrolysis of fused Magnesium Chloride from Brine s, wells, and Sea Water : :- → Mg :- → Cl2 ( Gas ) + 2 e- The has taken over as the dominant supplier, pegged at 60% world market share, which increased from 4% in 1995. Unlike the above described Electrolytic process, China is almost completely reliant on a different method of obtaining the metal from its ores, the Silicothermic Pidgeon Process . ''See also .'' COMPOUNDS IN LIVING ORGANISMS See Also: magnesium in biological systems Organic magnesium is important in both Plant and Animal life. Chlorophyll s are magnesium-centered Porphyrin s. The adult daily nutritional requirement, which is affected by various factors including sex, weight and size, is 300-400 Mg /day. Many Enzyme s require the presence of magnesium ions for their catalytic action, especially enzymes utilizing ATP . Inadequate magnesium intake frequently causes muscle Spasm s, and has been associated with Cardiovascular Disease , Diabetes , High Blood Pressure , Anxiety disorders and Osteoporosis . Acute deficiency is rare. The DRI upper tolerated limit for Supplemental magnesium is 350 mg/day. The most common symptom of excess magnesium is Diarrhea . Infants should not be given magnesium supplements. FOOD SOURCES Green vegetables such as Spinach provide magnesium because the center of the Chlorophyll molecule contains magnesium. Nut s, Seed s, and some whole grains are also good sources of magnesium. Although magnesium is present in many foods, it usually occurs in small amounts. As with most nutrients, daily needs for magnesium cannot be met from a single food. Eating a wide variety of foods, including five servings of fruits and vegetables daily and plenty of whole grains, helps to ensure an adequate intake of magnesium. The magnesium content of refined foods is usually low. Whole-wheat bread, for example, has twice as much magnesium as white bread because the magnesium-rich germ and bran are removed when white flour is processed. The table of food sources of magnesium suggests many dietary sources of magnesium. Water can provide magnesium, but the amount varies according to the water supply. "Hard" Water contains more magnesium than "soft" water. Dietary surveys do not estimate magnesium intake from water, which may lead to underestimating total magnesium intake and its variability. Too much magnesium in the diet can make it difficult for your body to absorb calcium. On the other hand not enough magnesium can lead to irregular heartbeats, high blood pressure, insomnia and muscle spasms. Following are some foods and the amount of magnesium in them:
ISOTOPES 26Mg is a stable isotope that has found application in Isotopic Geology , similar to that of Aluminium . 26Mg is a Radiogenic daughter product of 26Al, which has a Half-life of 717,000 years. Large enrichments of stable 26Mg have been observed in the Ca-Al-rich Inclusions of some Carbonaceous Chondrite Meteorite s. The anomalous abundance of 26Mg is attributed to the decay of its parent 26Al in the inclusions. Therefore, the meteorite must have formed in the Solar Nebula before the 26Al had decayed. Hence, these fragments are among the oldest objects in the Solar System and have preserved information about its earliest history. It is conventional to plot 26Mg/24Mg against an Al/Mg ratio. In an Isochrone plot, the Al/Mg ratio plotted is27Al/24Mg. The slope of the isochron has no age significance, but indicates the initial 26Al/27Al ratio in the sample at the time when the systems were separated from a common reservoir. PRECAUTIONS Magnesium metal and alloys are highly flammable in their pure form when molten, as a powder, or in ribbon form. Burning or molten magnesium metal reacts violently with water. Magnesium powder is an explosive hazard. One should wear safety glasses while working with magnesium. The bright white light (including Ultraviolet ) produced by burning magnesium can damage the eyes. Water should not be used to extinguish magnesium fires, because it can actually feed the fire, according to the reaction: {Link without Title} :Mg (s) + 2 H2O (v) → Mg(OH)2 (aq) + H2 (g) :or in words: :Magnesium (solid) + steam → Magnesium hydroxide ( Aqueous ) + Hydrogen (gas) Carbon dioxide dry chemical fire extinguisher should be used if available, or else the fire should be covered with Sand . An easy way to put out small metal fires is to place a polyethene bag filled with dry sand on top of the fire. The heat of the fire will melt the bag and the sand will flow out onto the fire. SEE ALSO EXTERNAL LINKS
|