Distribution in nature
Magnesium is a characteristic element of the Earth's mantle and the crust it contains about 2.35% by weight.In nature, it occurs only in the form of compounds.There are more than 100 minerals containing magnesium, most of them - silicates, and aluminum silicates.In seawater, it is smaller than sodium, but most other metals.
The biosphere is constantly going on migration and differentiation of the element - the dissolution and precipitation of salts, as well as sorption magnesium clays.He slightly delayed in the biological cycle, acting together with the river runoff into the ocean.
Magnesium is present in plant and animal organisms, a part of the green pigment chlorophyll, and it was found in ribosomes.This chemically element activates many enzymes involved in maintaining the pressure in the cel
ls, ensures the stability of chromosome structure and of colloidal systems.Animals get it from food, the daily human need for magnesium is 0.3-0.5 In the body, it accumulates in the liver, and then goes into the muscle and bone.
Physical and chemical properties
Magnesium - a relatively soft, ductile and malleable metal, and its mechanical properties are directly dependent on the method of processing.In the air it tarnishes because of the formation on the surface of a thin oxide film.Chemically magnesium sufficiently active, it displaces the majority of metals from aqueous solutions of their salts.Heating to 300-350 ° C does not lead to its substantial oxidation, but at a temperature of about 600 ° C, the oxide film is destroyed and the metal burns bright white flame.
Magnesium hardly reacts with cold water, if it is not filled with air, but because of slow boiling displaces hydrogen.At 400 ° C begins its reaction with water vapor.Numerous organometallic compounds of this element determines its major role in organic synthesis.
The industry magnesium produced by electrolysis that occurs at 720-750 ° C.For this purpose, anhydrous magnesium chloride, carnallite or dehydrated, the cathodes are made of steel and the anodes - of graphite.
also apply metallothermal and coal chemical methods.In the first case the charge of briquettes and the reducing agent calcined dolomite, they were heated in vacuum to 1280-1300 ° C, after which the magnesium vapor is condensed at 400-500 ° C.In carbothermic method for producing briquettes from a mixture of magnesium oxide with carbon in an electric furnace heated to 2100 ° C, and then distilled off and condensed vapors.