The iron

The iron is an element of the eighth group of the fourth period of the periodic table of chemical elements with atomic number 26. Iron is one of the most common metal in the earth's crust. This malleable metal silvery white color with high chemical reactivity. Iron corrodes rapidly at high temperatures or high humidity air. In pure oxygen it burns, and in finely divided iron ignites spontaneously in air.

The iron is an element of the eighth group of the fourth period of the periodic table of chemical elements with atomic number 26

The rare nature of the iron in its pure form, it is often found in the composition of iron-nickel meteorites. Iron is usually called its alloys with a low content of impurities. In practice frequently used iron alloys with carbon: a steel (up to 2,14 wt% carbon), a cast iron (more than 2,14 wt% carbon), as well as steel with alloying additions of metals (chromium, manganese, nickel and etc.).

As a tool material, iron has been known since ancient times. The oldest products made of it date back to the 4th millennium BC and relate to the Sumerian and Egyptian civilizations. But the first to master the method of smelting iron Hittites, as indicated by the ancient (2nd millennium BC) References to it in the texts of the Hittites. At that time, iron was used as jewelry metal, it made thrones and other insignia of royal power. Romans already able to bring the furnace temperature to the melting of steel (about 1400 degrees, and pure iron melts at 1535 degrees). This forms a cast iron with a melting point of 1100 1200 degrees, very fragile in the solid state (not even amenable to forging).

The iron is one of the most common elements in the solar system, especially on the terrestrial planets. A large part of the iron of the terrestrial planets is in the cores of planets, where its content is estimated to be about 90%. Its content in the earth's crust is 5% and about 12% of the mantle. Of the metals iron inferior to the prevalence in the earth's crust only aluminum. In the nucleus is only about 86% iron, and 14% in the mantle.

In crystal-chemical properties of ion Fe2+ is close to the ions Mg2+ and Ca2+. In view of the similarity crystal-chemical iron replaces the calcium and magnesium in many silicates . In this case its content in minerals of variable composition generally increases with decreasing temperature.

There are a number of minerals and ores that contain iron. The greatest practical importance are hematite (hematite, Fe2O3; contains up to 70% Fe), magnetic iron ore (magnetite, FeFe2O4, Fe3O4; contains 72,4% Fe), limonite (goethite and hydrogoethite respectively FeOOH and FeOOH*nH2O). Widespread iron sulfides pyrite FeS2 (sulfur or iron pyrites) and pyrrhotite. Pyrite is used to produce sulfuric acid and pyrrhotite often contains nickel and cobalt. In industry, iron is produced from iron ore is mainly hematite (Fe2O3) and magnetite (FeO*Fe2O3).

In the man, the iron contained in an amount of up to 4 g. It is advantageously included in the composition of hemoglobin (75%). In addition, it is in the liver, spleen and bone marrow. A lot of iron contained in the cytoplasm, where it is a process involving intracellular respiration.

Food should be rich in iron. It is contained in the form of compounds in the liver, meat, egg yolk, wheat, rye, potatoes, vegetables, apples, grapes. For people, especially after the loss of blood, doctors prescribe a special diet and iron.

Interestingly, the female body requires twice as much iron as the men body. The daily requirement of iron for men body is about 5 mg, and for women body up to 10 mg.

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