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Gaffer Variety:
Elements 10 SN2 012:
By Willie Gaffer:
Magnesium:
Magnesium, symbol Mg, is a light, silvery-white, moderately hard metallic element that in ribbon or powder form burns with a brilliant white flame. It is used in structural alloys, pyrotechnics, flash photography, and incendiary bombs. The atomic number is 12 the atomic weight is 24.312, the melting point is 649°C, the boiling point 1,090°C, and the specific gravity is 1.74 at 20°C. It has a valence of 2 an resides in group 2A if the periodic table.
At about 2.5 percent, Magnesium is the eighth most abundant element in the Earth's crust. We find it in minerals such as magnesite, dolomite, brucite, serpentine, chrysolite, meerschaum, talc, and most kinds of asbestos. Ocean water contains about 0.13 percent magnesium in the form of magnesium chloride. This is what gives seawater its bitter taste. We also have Magnesium in our cells. There, it acts as a catalyst for enzyme reactions in carbohydrate metabolism. That reaction is, of course, essential to life.
Magnesium is commercially produced by electrolysis of molten magnesium chloride (MgCl2), processed mainly from seawater and by the direct reduction of its compounds. It’s use in polytechnics and photoflash was once it’s main use. Now, because it is so light, alloys of magnesium have found applications in the aerospace industry. That use, as these developments often do, has now trickled down to the consumer products level.
Magnesium occurs in nature as a mixture of three isotopes: magnesium-24, magnesium-26, and magnesium-25. It is a very strong reducing agent, reacting with most acids or with boiling water to liberate hydrogen, but is resistant to most alkalis. In compounds it always exhibits a +2 oxidation state because of the loss or sharing of its two outer shell electrons.
Magnesium carbonate, MgCO3, occurs in nature as the mineral magnesite and is an important source of elemental magnesium. It can be produced artificially by the action of carbon dioxide on a variety of magnesium compounds. The odorless white powder has many industrial uses—e.g., as a heat insulator for boilers and pipes and as an additive in food, pharmaceuticals, cosmetics, rubbers, inks, and glass.
Magnesium hydroxide, Mg(OH)2, is a white powder produced in large quantities from seawater by the addition of milk of lime. It is the primary raw material in the production of magnesium metal. In water it forms a suspension known as milk of magnesia, which has long been used as an antacid and a laxative. Remember, as a kid, when your ma made you take a spoonful of that crap? Argh!
There are many other compounds of Magnesium with many commercial applications. Among these are cement for flooring, textile manufacturing, high temperature bricks, insulation, both thermal and electrical, fertilizer, rubber, and plastic. The list goes on.
Aluminum:
Aluminum, symbol Al, is a silvery-white, ductile metallic element. We all know what it looks like. Jus look at the beer and pop cans in your super market. It is the most abundant metallic element in the earth's crust, but we find it only in combination, mostly bauxite. Bauxite is a mixture of hydrated aluminum oxides, but it usually contains oxides of iron and silicon as well. It is the main source of aluminum and its compounds. It is found pretty much everywhere.
Aluminum has excellent conductive and thermal properties, similar to, but less that that of copper. It is used to form many hard, light, corrosion-resistant alloys. In fact, it is the most used nonferrous metal we have. The atomic number is 13, the atomic weight is 26.98, the melting point is 660.2°C, the boiling point is 2,467°C, and the specific gravity 2.69.Aluminu has a valence of 3 and it appears in column 3A of the periodic table. The electron configuration is 2, 8, 3.
Crystalline aluminum appears as corundum. This is an extremely hard aluminum oxide, Al2O3, that occurs in gem varieties such as ruby and sapphire and in a common black, brown, or blue form used chiefly in abrasives. Aluminum is also found in other gemstones such as topaz and garnet.
Aluminum became inexpensive when Charles Martin Hall in the
Pure aluminum is very soft and weak; commercial aluminum with small amounts of silicon and iron added is hard and strong. Ductile and highly malleable, aluminum can be drawn into wire or rolled into thin foil. The metal is only about one-third as dense as iron or copper. Though chemically active, aluminum is nevertheless highly corrosion-resistant because in air a hard, tough oxide film forms on its surface.