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What is metallic iron? Iron. Structure. Properties. Iron compounds. Characteristic oxidation states

Lesson objectives:

Introduce students to the side group element Periodic table– iron, its structure, properties.
Know the location of iron in nature, methods of obtaining it, application, physical properties.
Be able to characterize iron as an element of a secondary subgroup.
Be able to prove Chemical properties iron and its compounds, write reaction equations in molecular, ionic, redox form.
To develop students’ skills in composing equations of reactions involving iron, to form students’ knowledge of qualitative reactions to iron ions.
Cultivate interest in the subject.

Equipment: iron (powder, pin, plate), sulfur, oxygen flask, hydrochloric acid, iron(II) sulfate, iron(III) chloride, sodium hydroxide, red and yellow blood salts.

DURING THE CLASSES

I. Organizational moment

II. Checking homework

III. Learning new material

1. Teacher's introduction.

– The importance of iron in life, its role in the history of civilization. One of the most common metals in earth's crust is iron. It began to be used much later than other metals (copper, gold, zinc, lead, tin), which is most likely due to the low similarity of iron ore with the metal. To primitive people it was very difficult to guess that metal could be obtained from ore, which could be successfully used in manufacturing various items, was affected by the lack of tools and necessary devices to organize such a process. Quite a long time passed before man learned to extract iron from ore and make steel and cast iron from it.
On this moment Iron ores are a necessary raw material for ferrous metallurgy, those minerals that no developed industrial country can do without. For the year, global production iron ores is approximately 350,000,000 tons. They are used for smelting iron (carbon content 0.2-0.4%), cast iron (2.5-4% carbon), steel (2.5-1.5% carbon). Steel has the most widespread use in industry than iron and cast iron, which is why there is greater demand for its smelting.
To smelt cast iron from iron ores, blast furnaces are used that run on coal or coke; steel and iron are melted from cast iron in reverberatory open-hearth furnaces, Bessemer converters, or the Thomas method.
Ferrous metals and their alloys are of great importance in the life and development of human society. All kinds of household and consumer items are made of iron. For the construction of ships, aircraft, railways, cars, bridges, railways, various buildings, equipment and other things, hundreds of millions of tons of steel and cast iron are used. There is no such industry Agriculture and industry in which iron and its various alloys would not be used.
The few minerals commonly found in nature that contain iron are iron ore. Such minerals include: brown iron ore, hematite, magnetite, and others that form large deposits and occupying huge areas.
The chemical relation of magnetite or magnetic iron ore, which has an iron-black color and a unique property - magnetism, is a compound consisting of iron oxide and iron oxide. IN natural environment it can be found both in the form of granular or solid masses, and in the form of well-formed crystals. Iron ore is richest in the metallic iron content of magnetite (up to 72%).
The largest deposits of magnetite ores in our country are located in the Urals, in the Vysokaya, Blagodat, Magnitnaya mountains, in some areas of Siberia - the Angara River basin, Mountain Shoria, on the territory of the Kola Peninsula.

2. Work with the class. Characteristics of iron as a chemical element

a) Position in the periodic table:

Exercise 1. Determine the position of iron in the Periodic Table?

Answer: Iron is located in the 4th major period, even row, 8th group, minor group.

b) structure of the atom:

Task 2. Draw the composition and structure of the iron atom, electronic formula and cells.

Answer: Fe +3 2) 8) 14) 2)metal

p = 26
e = 26
n = (56 – 26) = 30

1s 2 2s 2 2p 6 3s 2 3p 6 3d 6 4s 2

Question. On which layers of iron are the valence electrons located? Why?

Answer. Valence electrons are located on the last and penultimate layers, since this is an element of the secondary subgroup.

Iron is classified as a d-element; it is part of the triad of elements - metals (Fe-Co-Ni);

c) redox properties of iron:

Question. What is iron - an oxidizing agent or a reducing agent? What oxidation states and valence does it exhibit?

Answer:

Fe 0 – 2e = Fe +3) reducing agent
Fe 0 – 3e = Fe +3
s.o.+ 2,+ 3; valency = II and III, valency 7 – does not show;

d) iron compounds:

FeO – basic oxide
Fe(OH) 2 – insoluble base
Fe 2 O 3 – oxide with signs of amphotericity
Fe(OH) 3 – a base with signs of amphotericity
Volatile hydrogen compounds are not.

d) being in nature.

Iron is the second most abundant metal in nature (after aluminum). In its free state, iron is found only in meteorites. The most important natural compounds:

FeO*3HO – brown iron ore,
FeO – red iron ore,
FeO (FeO*FeO) – magnetic iron ore,
FeS – iron pyrite (pyrite)

Iron compounds are found in living organisms.

3. Characteristics of the simple substance iron

a) molecular structure, type of bond, type of crystal lattice; (independent)

b) physical properties of iron

Iron is a silver-gray metal that has great malleability, ductility and strong magnetic properties. The density of iron is 7.87 g/cm 3, the melting point is 1539 t o C.

c) chemical properties of iron:

Iron atoms donate electrons in reactions and exhibit oxidation states of + 2, + 3 and sometimes + 6.
In reactions, iron is a reducing agent. However, at ordinary temperatures it does not interact even with the most active oxidizing agents (halogens, oxygen, sulfur), but when heated it becomes active and reacts with them:

2Fe +3Cl 2 = 2FeCl 3 Iron(III) chloride
3Fe + 2O 2 = Fe 2 O 3 (FeO*Fe O) Iron(III) oxide
Fe +S = FeS Iron(II) sulfide

At very high temperatures, iron reacts with carbon, silicon and phosphorus.

3Fe + C = Fe 3 C Iron carbide (cementite)
3Fe + Si = Fe 3 Si Iron silicide
3Fe + 2P = Fe 3 P 2 Iron phosphide

Iron reacts with complex substances.
In humid air, iron quickly acidifies (corrodes):

4Fe + 3O 2 + 6H 2 O = 4Fe(OH) 3
Fe(OH) 3 ––> FeOOH + H 2 O
Rust

Iron is in the middle of the electrochemical voltage series of metals, therefore it is a metal average activity. The reducing ability of iron is less than that of alkali, alkaline earth metals and aluminum. Only at high temperatures does hot iron react with water:

3Fe + 4H 2 O = Fe 3 O 4 + 4H 2

Iron reacts with dilute sulfuric and hydrochloric acids, displacing hydrogen from them:

Fe + 2HCl = FeCl 2 + H 2
Fe + H 2 SO 4 = FeSO 4 + H 2
Fe 0 + 2H + = Fe 2+ + H 2 0

At ordinary temperatures, iron does not interact with concentrated sulfuric acid, since it is passivated by it. When heated, concentrated sulfuric acid oxidizes iron to iron(III) sulfate:

2Fe + 6H 2 SO 4 = Fe 2 (SO 4) 3 + 3SO 2 + 6H 2 O

Dilute nitric acid oxidizes iron to iron(III) nitrate:

Fe + 4HNO 3 = Fe(NO 3) 3 + NO + 2H 2 O

Concentrated nitric acid passivates iron.

From salt solutions, iron displaces metals that are located to the right of it in the electrochemical voltage series:

Fe + CuSO 4 = FeSO 4 + Cu,

d) use of iron (on your own)

e) receiving (together with students)

In industry, iron is obtained by reducing it from iron ores with carbon (coke) and carbon monoxide (II) in blast furnaces.
The chemistry of the blast furnace process is as follows: