first products of iron and its alloys have been found during the excavations, and date from about the 4th millennium BC.That is, the ancient Egyptians and Sumerians used meteoric deposits of the substance to produce jewelry and household items, as well as weapons.
Today, various types of iron compounds and pure metal - is the most common and used material.No wonder the XX century iron was considered.After all, before the advent and widespread plastics and related materials it is this compound had to man crucial.What is this element and any substance forms, we consider in this article.
chemical element iron
If we consider the structure of the atom, you should first specify the location in the periodic system.
- serial number - 26.
- period - the fourth largest.
- Group of Eight, the subgroup sideline.
- atomic weight - 55.847.
- structure of the outer electron shell is denoted by the formula 3d64s2.
- chemical symbol - Fe.
- name - iron, reading in the formula - "Ferrum".
- In nature, there are four stable isotopes of the element with mass numbers 54, 56, 57, 58.
chemical element iron is also about 20 different isotopes, which do not differ stability.Possible degree of oxidation, which can be given atom:
is important not only to the item itself, but also its various compounds and alloys.
As simple substance, the physical properties of iron has a pronounced metallism.That is a silvery-white metal with a gray tint with a high degree of malleability and ductility and high melting and boiling points.If we consider the characteristics in more detail, then:
- melting point - 1539 0 C;
- boil - 2862 0 C;
- activity - medium;
- refractoriness - high;
- exhibits pronounced magnetic properties.
Depending on the conditions and temperatures, there are several modifications which forms iron.Physical properties distinguish them from what is different crystalline lattice.
- alpha form, or ferrite, there is to a temperature of 769 0C.
- from 769 to 917 0C - beta form.
- 917-1394 0C - gamma form or austenite.
- Over 1394 0C - Sigma iron.
All models have different types of crystal lattice structure, as well as different magnetic properties.Chemical properties
As mentioned above, a simple iron compound exhibits high reactivity.However, in finely divided form is capable of spontaneously ignite in air and in pure oxygen burns the metal itself.
corrosion ability is high, so the alloys of the substance covered by doping compounds.Iron is able to interact with:
- oxygen (including air);
- under heating - nitrogen, phosphorus, carbon and silicon;
- a less active metal salts, restoring them to the simple substances;
- with acute water vapor;
- with salts of iron in the oxidation state +3.
obvious that showing such activity, the metal is able to form different compounds, diverse and polarity properties.And so it happens.Iron and its compounds are extremely varied and are used in various fields of science, technology, human industrial activity.
Distribution in nature
Natural iron compounds are quite common, because it is the second most abundant element on the planet after aluminum.This pure metal is extremely rare in meteorites, indicating its large clusters it is in space.The bulk of the composition is contained in ores, rocks and minerals.
If we talk about the percentage of the element in nature, it can result in the following figures.
- nuclei of terrestrial planets - 90%.
- in the earth's crust - 5%.
- in the Earth's mantle - 12%.
- in the Earth's core - 86%.
- in river water - 2 mg / l.
- in marine and ocean - 0.02 mg / l.
most common form of iron compounds following minerals:
- limonite or limonite;
- milanterit and others.
This is not a complete list, because they are really very much.In addition, widely different alloys that are human.This, too, such compounds of iron, without which it is difficult to imagine modern life people.These are two basic types:
iron is also a valuable addition to the composition of many nickel alloys.
compounds of iron (II)
These include those in which the degree of oxidation forming element is 2.They are quite numerous, because they include:
- binary compounds;
- complex salt;
formulas of chemical compounds in which the iron oxidation state exhibits specified for each individual class.Consider the most important and common ones.
- oxide of iron (II). black powder, insoluble in water.Character connections - mostly.Able to quickly oxidize, however, and reduced to a simple substance could just as easily.Dissolved in acid to form the corresponding salt.Formula - FeO.
- hydroxide iron (II). is a white amorphous precipitate.It is formed by the reaction of salts with bases (alkalis).Shows weak basic properties, it is capable of rapidly oxidized in air to iron compounds 3.Formula - Fe (OH) 2.
- salts element in this oxidation state. typically have a pale-green solution is well oxidized even in air, getting dark brown color and passing to 3. The iron salt dissolved in water.Exemplary compounds: FeCL2, FeSO4, Fe (NO3) 2.
practical value among the identified compounds have multiple connections.First, iron chloride (II).It is the main supplier of ions in the human body, the patient's anemia.When such a disease is diagnosed in a patient, he prescribed complex preparations which are based on the objective compound.This happens shortfall of iron in the body.
Second, iron sulfate, that is iron sulfate (II), with copper is used to kill pests on crops.The method proved to be effective is not the first dozen years, so it is very appreciated by gardeners.
This compound, which is a hydrated iron sulfate and ammonium.The formula is written it as FeSO4 * (NH4) 2SO4 * 6H2O.One of the compounds of iron (II), which has been widely used in practice.The main areas of human use of the following.
- Research and Laboratory titrimetric analysis (for the determination of chromium, potassium permanganate, vanadium).
- Medicine - as an additive in foods with a shortage of iron in the body of the patient.
- for impregnation of wood products, as Mohr's salt protects against decay processes.
There are other areas in which the substance is used.It received its name in honor of the German chemist, first discovered showing the properties.
substances in the oxidation state of iron (III)
properties of iron compounds, in which it has an oxidation state +3 are somewhat different from the above.Thus, the nature of the oxide and hydroxide is no longer basic, and amphoteric pronounced.We give a description of the main substance.
- iron oxide (III). powder fine-grained, reddish-brown color.Insoluble in water, it exhibits the properties of a weakly acidic, amphoteric longer.Formula: Fe2O3.
- iron hydroxide (III). substance precipitated by the action of alkalis on appropriate iron salts.The nature of his pronounced amphoteric, color brown-brown.Formula: Fe (OH) 3.
- salts, which include cation Fe3 +.There are many allocated, except carbonate, as hydrolysis and produces carbon dioxide.Examples of some salts of formula: Fe (NO3) 3, Fe2 (SO4) 3, FeCL3, FeBr3 and others.
Among these examples from a practical point of view is important so crystalline as FeCL3 * 6H2O, hexahydrate or ferric chloride (III).It is used in medicine to stop the bleeding and filling of the iron ions in the body for anemia.
nonahydrate Iron (III) sulfate is used for drinking water purification, as acting as a coagulant.
Iron compounds (VI)
formulas of chemical compounds of iron, where it has a particular oxidation state 6 can be written as follows:
- MgFeO4 and others.
They all have a common name - ferrates - and have similar properties (strong reducing agents).Also, they can be decontaminated and have a bactericidal effect.This allows their use for the treatment of drinking water on a commercial scale.
very important in analytical chemistry, and not only are special substances.Those that form in aqueous salt solutions.This complex iron compound.The most popular and well-studied are the following.
- hexacyanoferrate (II) potassium K4 [Fe (CN) 6]. Another name for the connection - yellow blood salt.It is used for the qualitative detection of iron ions in a solution of Fe3 +.As a result of the solution acquires a beautiful bright blue color as the other complex forms - Prussian blue KFe3 + [Fe2 + (CN) 6].Since ancient times was used as a dye for fabrics.
- hexacyanoferrate (III) potassium K3 [Fe (CN) 6]. Another name - red blood salt.It is used as a reagent to determine the quality of the iron ion Fe2 +.This produces a blue precipitate having the name turnbuleva blue.Also used as a dye for fabric.
Iron composed of organic substances
Iron and its compounds, as we have seen, are of great practical importance in the economic life of man.However, in addition, its biological role in the body is not less great, on the contrary.
There is one very important organic compound, a protein, which includes the item.This hemoglobin.It is thanks to him going on the transport of oxygen and made uniform and timely exchange of gases.Therefore, the role of iron in vital processes - breathing - is huge.
Total inside of the human body contains about 4 grams of iron, which must be constantly replenished through food consumed.