The purpose of the lesson: formation of a system of knowledge about the position of metals in the Periodic Table and their general properties.

Lesson Objectives:

Educational - to consider the position of metals in the system of elements of D.I. Mendeleev, to acquaint students with the basic properties of metals, to find out what causes them, to introduce the concept of metal corrosion

Developing - to be able to find metals in the PSCE table, to be able to compare metals and non-metals, to explain the reasons for the chemical and physical properties of metals, to develop students' theoretical thinking and their ability to predict the properties of metals based on their structure.

Upbringing - to promote the development of students' cognitive interest in the study of chemistry

Lesson type: a lesson in learning new material.

Teaching methods : verbal and visual

During the classes:

Duration of the lesson.

Organizational moment (1 min.)

Knowledge update (3 min)

Learning new material

1.1. Position in the periodic system. (10 min)

1.2. Features of the electronic structure of atoms. (10 min)

1.3. Reducing properties of metals. (10 min)

2.1. Metallic bond. (5 minutes)

4. Emotional unloading 2 min

2.2. Physical properties. (10 min)

3. Chemical properties. (17 minutes)

4. Corrosion of metals. (5 min)

Fastening (15 min)

Homework (3 min)

Lesson summary (1min)

Organizing time

(Mutual greeting, fixation of those present).

Knowledge update. At the beginning of the lesson, the teacher focuses the attention of students on the importance of a new topic, determined by the role that metals play in nature and in all spheres of human activity.. Industry

The teacher reads the riddle:

I am hard, malleable and ductile,

Brilliant, everyone needs it, practical.

I already gave you a hint,

So who am I ...? and offers to write down the answer in a notebook in the form of a lesson topic?

Learning new material

Lecture plan.

1. Characteristics of the metal element.

1.2. Features of the electronic structure of atoms.

1.3. Reducing properties of metals.

2. Characteristics of a simple substance.

2.1. Metallic bond.

2.2. Physical properties.

3. Chemical properties.

4. Corrosion of metals.

1.1. Position in the periodic system.

The conventional boundary between metal elements and non-metal elements runs along the diagonal B (boron) - (silicon) - Si (arsenic) - Te (tellurium) - As (astatine) (trace it in D. I. Mendeleev's table) ..

The initial elements formthe main subgroup of group I and are called alkali metals ... They got their name from the name of the corresponding hydroxides, readily soluble in water - alkalis.

Of the elements of the main subgroups of the following groups, metals include: in group IV germanium, tin, lead (32,50,82) (the first two elements - carbon and silicon - non-metals), in group V antimony and bismuth (51,83) (the first three elements - non-metals), in group VI only the last element - polonium (84) - a pronounced metal... In the main subgroups VII and VIII of groups, all elements are typical non-metals.

As for the elements of the secondary subgroups, they are all metals.

Atoms of alkali metals contain only one electron at the external energy level, which they easily donate during chemical interactions, therefore they are the strongest reducing agents. It is clear that, in accordance with an increase in the atomic radius, the reducing properties of alkali metals increase from lithium to francium.

Following the alkali metals, the constituent elementsthe main subgroup of group II, are also typical metals with a strong reductive ability (their atoms contain two electrons on the outer level).Of these metals, calcium, strontium, barium and radium are called alkaline earth metals. ... These metals received this name because their oxides, which alchemists called "earths", when dissolved in water, form alkalis.

Metals also include elementsthe main subgroup of the III group, excluding boron.

Group 3 includes metals called the subgroup of aluminum.

1.2 Features of the electronic structure of metals.

Students, based on the knowledge gained, formulate the definition of "metal"

Metals are chemical elements whose atoms donate electrons to the outer (and sometimes pre-outer) electronic layer, turning into positive ions. Metals are reducing agents. This is due to the small number of electrons in the outer layer, the large radius of the atoms, as a result of which these electrons are weakly confined to the nucleus.Metal atoms have relatively large sizes (radii), therefore, their outer electrons are significantly distant from the nucleus and are weakly bound to it. And the second feature that is inherent in the atoms of the most active metals isthe presence of 1-3 electrons on the external energy level.
Metal atoms have a similarity in the structure of the outer electron layer, which is formed by a small number of electrons (mostly no more than three).
This statement can be illustrated by examples of Na, aluminum A1 and zinc Zn. Drawing up diagrams of the structure of atoms, if you wish, you can draw up electronic formulas and give examples of the structure of elements of long periods, for example, zinc.

Due to the fact that the electrons of the outer layer of metal atoms are weakly bound to the nucleus, they can be "given" to other particles, which happens during chemical reactions:

The property of metal atoms to donate electrons is their characteristic chemical property and indicates that metals exhibit reducing properties.

1.3 The reducing properties of metals.

How does the oxidizing ability of elements change?IIIperiod?

(The oxidizing properties increase in periods, and the reducing properties weaken. The reason for the change in these properties is the increase in the number of electrons in the last orbital.)

How do the oxidizing properties of the elements of group 4 of the main subgroup change?(from bottom to top, oxidizing properties increase. The reason for the change in these properties is a decrease in the radius of the atom (it is easier to accept than to give)

Based on the position of metals in the Periodic Table, what conclusion can be drawn about the redox properties of metal elements?

(Metals are reducing agents in chemical reactions, since they donate their valence electrons)

The students answer that the bond strength of the valence electrons with the nucleus depends on two factors:the magnitude of the charge of the nucleus and the radius of the atom. .

(recording the output in the students' notebooks) in the periods with an increase in the nuclear charge, the reducing properties decrease.

Elements - metals of side subgroups have slightly different properties.

The teacher proposes to compare the activity of the elements of the side subgroup.Cu, Ag, Au – activityl elements - metals fall. This pattern is also observed in the elements of the second side subgroupZn, Cd, Hg.The increase in electrons at the external level therefore the reducing properties are weakened

For elements of secondary subgroups - these are elements of 4-7 periods 31-36, 49-54 - with an increase in the ordinal element, the radius of the atoms will change little, and the magnitude of the nuclear charge increases significantly, therefore the strength of the bond of valence electrons with the nucleus increases, the reducing properties weaken.

2.1. Metallic bond.

The metallic bond is carried out through the mutual attraction of atom-ions and relatively free electrons.

Picture 1.
The structure of the crystal lattice of metals

In metals, valence electrons are held extremely weakly by atoms and are able to migrate. The atoms left without external electrons acquire a positive charge. They form a metallic crystal lattice.

The set of socialized valence electrons (electron gas), negatively charged, holds positive metal ions at certain points in space - the nodes of the crystal lattice, for example, of the metal silver.

External electrons can move freely and chaotically, therefore metals are characterized by high electrical conductivity (especially gold, silver, copper, aluminum).

Chemical bonding involves a certain type of crystal lattice. The metallic chemical bond promotes the formation of crystals with a metallic crystal lattice. At the sites of the crystal lattice are metal atom-ions, and between them freely moving electrons. The metallic bond differs from the ionic bond, because there are no anions, although there are cations. It also differs from the covalent one, since common electron pairs are not formed.

Emotional relief

The absence of what metal was described by Academician A.E. Fersman?

On the streets there would be a horror of destruction: there would be no rails, no cars, no steam locomotives, no cars, even the stones of the pavement would turn into clay dust, and the plants would start to wither and die without this metal. Destruction by a hurricane would take place all over the Earth, and the death of humanity would become inevitable. However, a person would not have lived up to this moment, because having lost three grams of this metal in his body and in his blood, he would have ceased to exist before the events drawn would have developed (Answer: All people would have died, having lost iron in their blood)

Name the metal of the counterfeiters

The name was given to the metal by the Spanish conquistadors, who in the middle of the 16th century. first met in South America (on the territory of modern Colombia) with a new metal that looks like silver. The name of the metal literally means "little silver", "silver".

This scornful name is explained by the exceptional refractoriness of the metal, which did not lend itself to remelting, was not used for a long time and was valued half as much as silver. They used this metal to make counterfeit coins.

Today, this metal, used as a catalyst and in jewelry, is one of the most expensive.

In its pure form, it does not exist in nature. Native platinum is usually a natural alloy with other noble (palladium, iridium, rhodium, ruthenium, osmium) and non-noble (iron, copper, nickel, lead, silicon) metals. To obtain it, nuggets are heated in boilers with "aqua regia" (a mixture of nitric and hydrochloric acids) and then "brought" by numerous chemical reactions, heating and melting.

Thus, the crystal lattice depends and is determined by the type of chemical bond, but at the same time is the reason for the physical properties.

2.2. Physical properties.

The teacher emphasizes that the physical properties of metals are determined precisely by their structure.

a)hardness - all metals except mercury, solids under normal conditions. The mildest are sodium, potassium. They can be cut with a knife; hardest chrome - scratches glass

b)density. Metals are divided into soft (5g / cm³) and heavy (less than 5g / cm³).

v)fusibility. Metals are divided into fusible and refractory.

G)electrical conductivity, thermal conductivity metals due to their structure. Chaotically moving electrons under the action of an electric voltage acquire a directional movement, as a result of which an electric current arises.

As the temperature rises, the amplitude of the motion of atoms and ions located in the nodes of the crystal lattice increases sharply, and this interferes with the movement of electrons, and the electrical conductivity of metals decreases.

It should be noted that in some non-metals, with an increase in temperature, the electrical conductivity increases, for example, in graphite, while with an increase in temperature, some covalent bonds are destroyed, and the number of freely moving electrons increases.

e)metallic luster - electrons filling the interatomic space reflect light rays, and do not transmit like glass. They fall on the nodes of the crystal lattice. Therefore, all metals in the crystalline state have a metallic luster. For most metals, all rays of the visible part of the spectrum are equally scattered, so they have a silvery-white color. Only gold and copper absorb to a large extent short wavelengths and reflect long wavelengths of the light spectrum, therefore they are yellow. The most brilliant metals are mercury, silver, palladium. All metals in powder, exceptAlandMg, lose their luster and are black or dark gray in color.

e)plastic

Mechanical action on a crystal with a metal lattice only causes displacement of atomic layers and is not accompanied by bond breaking, and therefore the metal is characterized by high plasticity.

3. Chemical properties.

According to their chemical properties, all metals are reducing agents, all of them relatively easily give up valence electrons, pass into positively charged ions, that is, they are oxidized ... The reducing activity of a metal in chemical reactions taking place in aqueous solutions reflects its position in the electrochemical series of metal voltages (Opened and compiled by Beketov)

The more to the left the metal stands in the series of electrochemical voltages of metals, the stronger it is a reducing agent, the strongest reducing agent is metallic lithium, gold is the weakest, and, conversely, the gold (III) ion is the strongest oxidizing agent, lithium (I) is the most weak.

Each metal is capable of reducing from salts in solution those metals that are in a series of voltages after it, for example, iron can displace copper from solutions of its salts. Remember, however, that the alkali and alkaline earth metals will interact directly with the water.

Metals, standing in the series of voltages to the left of hydrogen, are capable of displacing it from solutions of dilute acids, while dissolving in them.

The reducing activity of a metal does not always correspond to its position in the periodic system, because when determining the place of a metal in a row, not only its ability to donate electrons is taken into account, but also the energy spent on the destruction of the crystal lattice of the metal, as well as the energy spent on hydration of ions.

Interaction with simple substances

WITHoxygen most metals form oxides - amphoteric and basic:

4Li + O 2 = 2Li 2 Oh,

4Al + 3O 2 = 2Al 2 O 3 .

Alkali metals, with the exception of lithium, form peroxides:

2Na + O 2 = Na 2 O 2 .

WITHhalogens metals form salts of hydrohalic acids, for example,

Cu + Cl 2 = CuCl 2 .

WITHhydrogen the most active metals form ionic hydrides - salt-like substances in which hydrogen has an oxidation state of -1.

2Na + H 2 = 2NaH.

WITHgray metals form sulfides - salts of hydrogen sulfide acid:

Zn + S = ZnS.

WITHnitrogen some metals form nitrides, the reaction almost always proceeds when heated:

3Mg + N 2 = Mg 3 N 2 .

WITHcarbon carbides are formed:

4Al + 3C = Al 3 C 4 .

WITHphosphorus - phosphides:

3Ca + 2P = Ca 3 P 2 .

Metals can interact with each other, formingintermetallic compounds :

2Na + Sb = Na 2 Sb,

3Cu + Au = Cu 3 Au.

Metals can dissolve in each other at high temperatures without interacting, forming alloys.

The ratio of metals to acids.

Most often in chemical practice, such strong acids are used as sulfuric H 2 SO 4 , hydrochloric HCl and nitrogen HNO 3 .

WithHCl

The hydrogen ions H + act as an oxidizing agent, oxidizingmetals located in the line of activity to the left of hydrogen ... The interaction proceeds according to the scheme:

Me + HCl - salt + H 2

2 Al + 6 HCl → 2 AlCl 3 + 3 H 2

2│Al 0 – 3 e - → Al 3+ - oxidation

3│2H + + 2 e - → H 2 - recovery

"Tsarskaya vodka" (previously called vodka acids) is a mixture of one volume of nitric acid and three to four volumes of concentrated hydrochloric acid, which has a very high oxidative activity. This mixture is capable of dissolving some low-activity metals that do not interact with nitric acid. Among them is the "king of metals" - gold. This effect of "aqua regia" is explained by the fact that nitric acid oxidizes hydrochloric acid with the release of free chlorine and the formation of nitrogen (III) chloroxide, or nitrosyl chloride - NOCl:

Gold oxidation reactions proceed according to the following equations:

Au + HNO3 + 4 HCl → H + NO + 2H2O

If acids can interact with bases and basic oxides, and the key element in their composition is a metal, then is it possible for metals to interact with acids. Let's check it experimentally.

Magnesium interacts with acid under normal conditions, zinc - when heated, copper - does not interact.

A number of voltages are used in practice for a comparative assessment of the chemical activity of metals in reactions with aqueous solutions of salts and acids and for the assessment of cathodic and anodic processes during electrolysis:

The metals on the left are stronger reductants, than metals located to the right:they displace the latter from salt solutions . Metals in the row to the left of hydrogen displace hydrogen when interacting with aqueous solutions of non-oxidizing acids; the most active metals (up to and including aluminum) - and when interacting with water.

Metals in the row to the right of hydrogen do not interact with aqueous solutions of non-oxidizing acids under normal conditions.

During electrolysis, metals to the right of hydrogen are released at the cathode; the reduction of metals of moderate activity is accompanied by the evolution of hydrogen; the most active metals (up to aluminum) cannot be isolated under normal conditions from aqueous solutions of salts.

4. Corrosion of metals - physicochemical or chemical interaction between the metal (alloy) and the environment, leading to a deterioration in the functional properties of the metal (alloy), environment or the technical system that includes them.

The word corrosion comes from the Latin "corrodo" - "gnaw" (Late Latin "corrosio" means "erosion").

Corrosion is caused by a chemical reaction of a metal with environmental substances that occurs at the interface between the metal and the medium. Most often this is the oxidation of the metal, for example, with atmospheric oxygen or acids contained in solutions with which the metal comes into contact. Especially susceptible to this are metals located in the row of voltages (row of activity) to the left of hydrogen, including iron.

As a result of corrosion, iron rusts. This process is very complex and involves several stages. It can be described by the summary equation:

4Fe + 6H 2 O (moisture) + 3O 2 (air) = 4Fe (OH) 3

Iron (III) hydroxide is very unstable, quickly loses water and turns into iron (III) oxide. This compound does not protect the iron surface from further oxidation. As a result, the iron object can be completely destroyed.

To slow down corrosion, varnishes and paints, mineral oils and grease are applied to the metal surface. Underground structures are covered with a thick layer of bitumen or polyethylene. The inner surfaces of steel pipes and tanks are protected with cheap cement coatings.

For steel products, so-called rust converters containing phosphoric acid (H 3 RO 4 ) and its salt. They dissolve oxide residues and form a dense and durable phosphate film, which is able to protect the surface of the product for some time. Then the metal is covered with a primer layer, which should adhere well to the surface and have protective properties (usually red lead or zinc chromate is used). Only then can varnish or paint be applied.

Fastening (15 min)

Teacher:

Now, to consolidate, we will conduct a test.

Solve test tasks

1.Select a group of elements that contains only metals:

A) Al, As, P;B) Mg, Ca, Si;V) K, Ca, Pb

2. Select a group that contains only simple substances - non-metals:

A) K 2 O, SO 2 , SiO 2 ; B) H 2 , Cl 2 , I 2 ; V) Ca, Ba, HCl;

3. Indicate what is common in the structure of K and Li atoms:

A) 2 electrons on the last electron layer;

B) 1 electron on the last electron layer;

C) the same number of electronic layers.

4. Metallic calcium exhibits properties:

A) an oxidizing agent;

B) a reducing agent;

B) an oxidizing agent or a reducing agent, depending on the conditions.

5. The metallic properties of sodium are weaker than that of -

A) magnesium; B) potassium; B) lithium.

6. Inactive metals include:

A) aluminum, copper, zinc; B) mercury, silver, copper;

C) calcium, beryllium, silver.

7. What physical property is not common to all metals:

A) electrical conductivity, B) thermal conductivity,

B) solid state of aggregation under normal conditions,

D) metallic luster

8.Metals, when interacting with non-metals, exhibit the following properties:

a) oxidative;

b) restorative;

c) both oxidizing and reducing;

d) do not participate in redox reactions.

9.In the periodic table, typical metals are located

a) top

b) the bottom

in the upper right corner

d) lower left corner

Part B. The answer to the tasks of this part is a set of letters that should be written down

Establish correspondence.

With an increase in the ordinal number of an element in the main subgroup of group II of the Periodic Table, the properties of the elements and the substances they form change as follows:

1) the number of electrons at the outer level

A) increases

3) electronegativity

4) restorative properties

B) decreases

C) does not change

(Answers: 1-D, 2-A, 3-C, 4-B, 5-D)

TASKS FOR ANCHORING

№1. Complete the equations of practically feasible reactions, name the reaction products

Li + H 2 O =

Cu + H 2 O =Cu( OH) 2 + H 2

Ba + H 2 O =

Mg + H 2 O =

Ca + HCl =

2 Na +2 H 2 SO 4 ( TO)= Na 2 SO 4 + SO 2 + 2H 2 O

HCl + Zn =

H 2 SO 4 ( To) + Cu =CuSO 4 + SO 2 + H 2 O

H 2 S + Mg = MgS + H 2

HCl + Cu =

Home assignment: notes in notebooks, messages on the use of metals.

Teacher Suggests creating a syncwine on the topic.

Line 1: Noun (one per topic) (Metals)

Line 2: two adjectives

3 line: three verbs

4 line: four words combined into a sentence

5 line: a word expressing the essence of this topic.

Lesson summary

Teacher : And so, we examined the structure and physical properties of metals, their position in the periodic table of chemical elements of D.I. Mendeleev.

Metals make up most of the chemical elements. Each period of the periodic system (except for the 1st) chemical elements begins with metals, and with an increase in the number of the period, they become more and more. If in the 2nd period there are only 2 metals (lithium and beryllium), in the 3rd - 3 (sodium, magnesium, aluminum), then already in the 4th - 13, and in the 7th - 29.

Metal atoms have a similarity in the structure of the outer electron layer, which is formed by a small number of electrons (mostly no more than three).

This statement can be illustrated by examples of Na, aluminum A1 and zinc Zn. Drawing up diagrams of the structure of atoms, if you wish, you can draw up electronic formulas and give examples of the structure of elements of long periods, for example, zinc.

Due to the fact that the electrons of the outer layer of metal atoms are weakly bound to the nucleus, they can be "given" to other particles, which happens during chemical reactions:

The property of metal atoms to donate electrons is their characteristic chemical property and indicates that metals exhibit reducing properties.

When characterizing the physical properties of metals, one should note their general properties: electrical conductivity, thermal conductivity, metallic luster, plasticity, which are due to a single type of chemical bond - metallic and metallic crystal lattice. Their feature is the presence of freely moving shared electrons between ion-atoms located at the sites of the crystal lattice.

When characterizing the chemical properties, it is important to confirm the conclusion that in all reactions metals exhibit the properties of reducing agents, and to illustrate this by writing down the reaction equations. Particular attention should be paid to the interaction of metals with acids and salt solutions; in this case, it is necessary to refer to a number of metal voltages (a number of standard electrode potentials).

Examples of the interaction of metals with simple substances (non-metals):

With salts (Zn in the series of voltages is to the left of Cu): Zn + CuC12 = ZnCl2 + Cu!

Thus, despite the great variety of metals, they all have common physical and chemical properties, which is explained by the similarity in the structure of atoms and the structure of simple substances.

Introduction

Metals are simple substances with characteristic properties under normal conditions: high electrical conductivity and thermal conductivity, the ability to reflect light well (which determines their shine and opacity), the ability to take the desired shape under the influence of external forces (plasticity). There is another definition of metals - these are chemical elements characterized by the ability to donate external (valence) electrons.

Of all the known chemical elements, about 90 are metals. Most inorganic compounds are metal compounds.

There are several types of metal classification. The clearest is the classification of metals in accordance with their position in the periodic table of chemical elements - chemical classification.

If, in the "long" version of the periodic table, draw a straight line through the elements boron and astatine, then metals will be located to the left of this line, and non-metals to the right of it.

From the point of view of the structure of the atom, metals are subdivided into intransitive and transitional. Non-transition metals are located in the main subgroups of the periodic system and are characterized by the fact that their atoms are sequentially filled with electronic levels s and p. Intransitional metals include 22 elements of the main subgroups a: Li, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Al, Ga, In, Tl, Ge, Sn, Pb, Sb, Bi, Po.

Transition metals are located in side subgroups and are characterized by filling d - or f -electronic levels. The d -elements include 37 metals of side subgroups b: Cu, Ag, Au, Zn, Cd, Hg, Sc, Y, La, Ac, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo , W, Sg, Mn, Tc, Re, Bh, Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Hs, Mt.

The f-element includes 14 lanthanides (Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, D y, Ho, Er, Tm, Yb, Lu) and 14 actinides (Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No, Lr).

Among the transition metals, there are also rare earth metals (Sc, Y, La and lanthanoids), platinum metals (Ru, Rh, Pd, Os, Ir, Pt), transuranic metals (N p and elements with a higher atomic mass).

In addition to the chemical, there is also, although not generally accepted, but long established technical classification of metals. It is not as logical as a chemical one - it is based on one or another practically important feature of a metal. Iron and alloys based on it are classified as ferrous metals, all other metals are classified as non-ferrous. Distinguish between light (Li, Be, Mg, Ti, etc.) and heavy metals (Mn, Fe, Co, Ni, Cu, Zn, Cd, Hg, Sn, Pb, etc.), as well as groups of refractory (Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, R e), precious (Ag, Au, platinum metals) and radioactive (U, Th, N p, Pu, etc.) metals. Scattered (Ga, Ge, Hf, Re, etc.) and rare (Zr, Hf, Nb, Ta, Mo, W, Re, etc.) metals are also distinguished in geochemistry. As you can see, there are no clear boundaries between the groups.

History reference

Despite the fact that the life of human society without metals is impossible, no one knows for sure when and how a person first began to use them. The most ancient writings that have come down to us tell of primitive workshops in which smelt or metal was made and products were made from it. This means that man mastered metals earlier than writing. Digging up ancient settlements, archaeologists find tools of labor and hunting that people used in those distant times - knives, axes, arrowheads, needles, fish hooks and much more. The older the settlements, the rougher and more primitive were the products of human hands. The most ancient metal products were found during excavations of settlements that existed about 8 thousand years ago. These were mainly jewelry made of gold and silver, and arrowheads and spearheads made of copper.

The Greek word "metallon" was originally the beginning of the mine, mines, hence the term "metal" came from. In ancient times, it was believed that there are only 7 metals: gold, silver, copper, tin, lead, iron and mercury. This number correlated with the number of then known planets - the Sun (gold), the Moon (silver), Venus (copper), Jupiter (tin), Saturn (lead), Mars (iron), Mercury (mercury) (see the picture) ... According to alchemical concepts, metals originated in the bowels of the earth under the influence of the rays of the planets and gradually improved, turning into gold.

Man first mastered native metals - gold, silver, mercury. The first artificially obtained metal was copper, then it was possible to master the production of an alloy of copper with brine - bronze and only later - iron. In 1556, a book by the German metallurgist G. Agricola "On mining and metallurgy" was published in Germany - the first detailed guide to the production of metals that has come down to us. True, at that time, lead, tin and bismuth were still considered varieties of the same metal. In 1789, the French chemist A. Lavoisier, in his manual on chemistry, gave a list of simple substances, which included all the then known metals - antimony, silver, bismuth, cobalt, tin, iron, manganese, nickel, gold, pl -tinu, lead, tungsten and zinc. With the development of methods of chemical research, the number of known metals began to increase rapidly. In the 18th century. 14 metals were discovered, in the 19th century. - 38, in the 20th century. - 25 metals. In the first half of the 19th century. satellites of platinum were discovered, alkali and alkaline earth metals were obtained by electrolysis. In the middle of the century, cesium, rubidium, thallium and indium were discovered by spectral analysis. The existence of metals predicted by D.I.Mendeleev on the basis of his periodic law (these are gallium, scandium and germanium) has been brilliantly confirmed. The discovery of radioactivity at the end of the 19th century. entailed the search for radioactive metals. Finally, by the method of nuclear transformations in the middle of the 20th century. radioactive metals that do not exist in nature, in particular transuranic elements, were obtained.

Physical and chemical properties of metals.

All metals are solids (except for mercury, which is liquid under normal conditions); they differ from non-metals in a special type of bond (metallic bond). Valence electrons are weakly bound to a specific atom, and inside each metal there is a so-called electron gas. Most metals have a crystalline structure, and the metal can be thought of as a "rigid" crystal lattice of positive ions (cations). These electrons can more or less move around the metal. They compensate for the repulsive forces between the cations and, thus, bind them into a compact body.

All metals have high electrical conductivity (i.e., they are conductors, unlike non-metallic dielectrics), especially copper, silver, gold, mercury and aluminum; the thermal conductivity of metals is also high. A distinctive feature of many metals is their ductility (malleability), as a result of which they can be rolled into thin sheets (foil) and drawn into a wire (tin, aluminum, etc.), however, there are also quite brittle metals (zinc, antimony , bismuth).

In industry, not pure metals are often used, but their mixtures, called alloys. In an alloy, the properties of one component usually complement the properties of the other. So, copper has a low hardness and is of little use for the manufacture of machine parts, while copper-zinc alloys, called brass, are already quite hard and are widely used in mechanical engineering. Aluminum has good ductility and sufficient lightness (low density), but too soft. On its basis, ayuralumin alloy (duralumin) is prepared, containing copper, magnesium and manganese. Duralumin, without losing the properties of its aluminum, acquires a high hardness and therefore is used in aviation technology. Alloys of iron with carbon (and additives of other metals) are well-known cast iron and steel.

Metals vary greatly in density: for lithium it is almost half that of water (0.53 g / cm), and for osmium it is more than 20 times higher (22.61 g / cm 3). Metals also differ in hardness. The softest - alkali metals, they are easily cut with a knife; the hardest metal - chrome - cuts glass. The difference in the melting temperatures of metals is great: mercury is a liquid under normal conditions, cesium and gallium melt at the temperature of a human body, and the most refractory metal, tungsten, has a melting point of 3380 ° C. Metals, the melting temperature of which is higher than 1000 ° C, are referred to as refractory metals, below - to low-melting ones. At high temperatures, metals are capable of emitting electrons, which is used in electronics and thermoelectric generators to directly convert thermal energy into electrical energy. Iron, cobalt, nickel and gadolinium, after placing them in a magnetic field, are able to constantly maintain a state of magnetization.

Metals also have some chemical properties. Metal atoms relatively easily donate valence electrons and transform into positively charged ions. Therefore, metals are reducing agents. This, in fact, is their main and most general chemical property.

Obviously, metals as reducing agents will enter into reactions with various oxidizing agents, among which there may be simple substances, acids, salts of less active metals and some other compounds. Compounds of metals with halogens are called halides, with sulfur - sulfides, with nitrogen - nitrides, with phosphorus - phosphides, with carbon - carbides, with silicon - silicides, with boron - borides, with hydrogen - hydrides, etc. Many of these compounds have found important applications in new technology. For example, metal borides are used in radio electronics, as well as in nuclear technology as materials for regulating neutron radiation and protecting against it.

Under the action of concentrated oxidizing acids, a stable oxide film is also formed on some metals. This phenomenon is called passivation. So, in concentrated sulfuric acid such metals as Be, Bi, Co, Fe, Mg, and Nb are passivated (and do not react with it), and in concentrated nitric acid - metals Al, Be, Bi , Co, Cr, Fe, Nb, Ni, Pb, Th and U.

The more to the left the metal is located in this row, the more reducing properties it possesses, that is, it oxidizes more easily and passes in the form of a cation into a solution, but it is more difficult to recover from a cation into a free state.

One non-metal, hydrogen, is placed in a series of voltages, since this makes it possible to determine whether a given metal will react with acids - non-oxidizing agents in an aqueous solution (more precisely, it will be oxidized by hydrogen cations H +). For example, zinc reacts with hydrochloric acid, since in the series of voltages it stands to the left (up to) hydrogen. On the contrary, silver is not transferred into solution by hydrochloric acid, since it stands in the series of voltages to the right (after) of hydrogen. Metals behave similarly in dilute sulfuric acid. Metals in the series of stresses after hydrogen are called noble metals (Ag, Pt, Au, etc.)

Periodic system D. I. Mendeleev subdivided into ... period (excluding the first) begins alkaline metal and ends with a noble gas. Elements 2 ...

Periodic system elements Mendeleev

Abstract >> Chemistry

II. Periodic law and Periodic system chemical elements Discovery of D.I. Mendeleev Periodic Law Structure Periodic systems a) ... is a non-metal, and bismuth is metal). V Periodic the system typical metals are located in the IA group (Li ...

Periodic D.I. Mendeleev (2)

Biography >> Biology

Connections. He determined that metals correspond to basic oxides and bases, ... and hydroxides in some metals was causing confusion. The classification was ... atoms of chemical elements in Periodic the system DI. Mendeleev change monotonously, therefore ...

Periodic system and its significance in the development of chemistry by D.I. Mendeleev

Abstract >> Chemistry

Periods refer to s-elements (alkaline and alkaline earth metals), constituting Ia- and IIa-subgroups (highlighted ... the scientific basis of teaching chemistry. Conclusion Periodic system D. I. Mendeleev became the most important milestone in the development of atomic ...

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Slide captions:

The position of metals in the Periodic Table of D.I. Mendeleev. Features of the structure of atoms, properties.

The purpose of the lesson: 1. On the basis of the position of metals in the PSCE, come to an understanding of the structural features of their atoms and crystals (metal chemical bonds and crystal metal lattice). 2. To generalize and expand knowledge about the physical properties of metals and their classifications. 3. Develop the ability to analyze, draw conclusions based on the position of metals in the periodic table of chemical elements.

COPPER I'm going on small coins, I like to ring in bells, They erect a monument to me for this And they know: my name is….

IRON To plow and build - he can do everything, if the coal will help him in that ...

Metals are a group of substances with common properties.

The metals are elements of I-III groups of the main subgroups, and IV-VIII groups of secondary subgroups I group II group III group IV group V group VI group VII group VIII group Na Mg Al Ti V Cr Mn Fe

Of the 109 elements of PSCE, 85 are metals: they are highlighted in blue, green and pink (except for H and He)

The position of an element in the PS reflects the structure of its atoms. POSITION OF THE ELEMENT IN THE PERIODIC SYSTEM STRUCTURE OF ITS ATOMS Ordinal number of the element in the periodic system Nuclear charge of the atom Total number of electrons Group number Number of electrons at the external energy level. Highest valence of an element, oxidation state Period number Number of energy levels. The number of sublevels at the external energy level

Sodium atom model

The electronic structure of the sodium atom

Task 2. Make a diagram of the electronic structure of the aluminum and calcium atoms in the notebook yourself, following the example with the sodium atom.

Conclusion: 1. Metals are elements that have 1-3 electrons at the external energy level, less often 4-6. 2. Metals are chemical elements whose atoms donate electrons to the outer (and sometimes pre-outer) electronic layer, turning into positive ions. Metals are reducing agents. This is due to the small number of electrons in the outer layer, the large radius of the atoms, as a result of which these electrons are weakly confined to the nucleus.

A metallic chemical bond is characterized by: - ​​delocalization of the bond, because a relatively small number of electrons simultaneously bind many nuclei; - valence electrons move freely over the entire piece of metal, which is generally electrically neutral; - the metal bond does not have directionality and saturation.

Crystalline lattices of metals

Video information about metal crystals

The properties of metals are determined by the structure of their atoms. Metal property Property property hardness All metals, except mercury, are solids under normal conditions. The mildest are sodium, potassium. They can be cut with a knife; the hardest chrome - scratches glass. density Metals are divided into light (density 5g / cm) and heavy (density greater than 5g / cm). fusibility Metals are divided into low-melting and refractory electrical conductivity, thermal conductivity Chaotically moving electrons under the influence of electric voltage acquire directional motion, resulting in an electric current. metallic luster Electrons filling the interatomic space reflect light rays, and do not transmit plasticity like glass. Mechanical action on a crystal with a metal lattice only causes displacement of atomic layers and is not accompanied by bond breaking, and therefore the metal is characterized by high plasticity.

Check the assimilation of knowledge in the lesson by testing 1) Electronic formula of calcium. А) 1S 2 2S 2 2Р 6 3S 1 B) 1S 2 2S 2 2 Р 6 3 S 2 C) 1S 2 2S 2 2 Р 6 3 S 2 3S 6 4S 1 D) 1S 2 2S 2 2 Р 6 3 S 2 3 R 6 4 S 2

Test tasks 2 and 3 2) The electronic formula 1S 2 2S 2 2P 6 3S 2 3P 6 4S 2 has an atom: a) Na b) Ca c) Cu d) Zn 3) Electrical conductivity, metallic luster, plasticity, density of metals are determined: a ) the mass of atoms b) the melting point of metals c) the structure of metal atoms d) the presence of unpaired electrons

Test items 4 and 5 4) Metals interacting with non-metals exhibit properties a) oxidizing; b) restorative; c) both oxidizing and reducing; d) do not participate in redox reactions; 5) In the periodic table, typical metals are located in: a) the upper part; b) the lower part; in the upper right corner; d) lower left corner;

Correct answers Task number Correct answer option 1 D 2 B 3 C 4 B 5 D

Preview:

The purpose and objectives of the lesson:

1. On the basis of the position of metals in the PSCE, lead students to an understanding of the structural features of their atoms and crystals (metallic chemical bonds and crystalline metal lattice), to study the general physical properties of metals. Review and summarize knowledge about chemical bonding and metal crystal lattice.
2. To develop the ability to analyze, draw conclusions about the structure of atoms based on the position of metals in the PSCE.
3. Develop the ability to master chemical terminology, clearly formulate and express your thoughts.
4. To foster independent thinking in the course of educational activities.
5. To generate interest in the future profession.

Lesson form:

combined lesson with presentation

Methods and techniques:

Story, conversation, video demonstration of the types of crystal lattices of metals, test, drawing up diagrams of the electronic structure of atoms, demonstration of a collection of samples of metals and alloys.

Equipment:

1. Table “Periodic table of chemical elements of D.I. Mendeleev ";
2. Presentation of the lesson on electronic media.
3. Collection of samples of metals and alloys.
4. Projector.
5. Cards with the table "Characteristics of the structure of the atom by position in the PSCE"
   

DURING THE CLASSES

I. Organizational moment of the lesson.

II. Statement and announcement of the topic of the lesson, its goals and objectives.

Slide 1-2

III. Learning new material.

Teacher: Man has used metals since ancient times. Briefly about the history of the use of metals.

1 student message. Slide 3

In the beginning there was a copper age.

By the end of the Stone Age, man discovered the possibility of using metals for the manufacture of tools. The first such metal was copper.

The period of the spread of copper tools is called Chalcolithic or Chalcolithic , which translated from Greek means "copper". Copper was processed using stone tools using the cold forging method. Copper nuggets were turned into products under heavy hammer blows. At the beginning of the Copper Age, only soft tools, jewelry, and household items were made of copper. It was with the discovery of copper and other metals that the profession of a blacksmith began to emerge.

Later, casting appeared, and then people began to add tin or antimony to copper, to make bronze, more durable, strong, fusible.

Student message 2. Slide 3

Bronze - an alloy of copper and tin. The chronological boundaries of the Bronze Age date back to the beginning of the 3rd millennium BC. before the beginning of the 1st millennium BC

Student message 3. Slide 4

The third and final period of the primitive era is characterized by the spread of iron metallurgy and iron tools and marks the Iron Age. In its modern meaning, this term was introduced in the middle of the 9th century by the Danish archaeologist K. Yu. Thomson and soon spread in literature along with the terms “Stone Age” and “Bronze Age”.

Unlike other metals, iron, except for meteorite, is almost never found in its pure form. Scientists assume that the first iron that fell into the hands of man was of meteorite origin, and it is not for nothing that the iron is called a "heavenly stone." The largest meteorite found in Africa, it weighed about sixty tons. And in the ice of Greenland, they found an iron meteorite weighing thirty-three tons.

And now the Iron Age continues. Indeed, at present, iron alloys make up almost 90% of all metals and metal alloys.

Teacher.

Gold and silver - precious metals are currently used for the manufacture of jewelry, as well as parts in the electronics, aerospace industry, and shipbuilding. Where can these metals be used in shipping? The exceptional importance of metals for the development of society is due, of course, to their unique properties. Name these properties.

Demonstrate to students a collection of metal samples.

Students name such properties of metals as electrical conductivity and thermal conductivity, characteristic metallic luster, plasticity, hardness (except for mercury), etc.

The teacher asks the students a key question: what is the reason for these properties?

Expected response:properties of substances are due to the structure of molecules and atoms of these substances.

Slide 5. So, metals are a group of substances with common properties.

Demonstration of presentation.

Teacher: Metals are elements of 1-3 groups of main subgroups, and elements of 4-8 groups of secondary subgroups.

Slide 6. Task 1 ... On your own, using PSCE, add the representatives of the groups, which are metals, in the notebook.

							VIII

Hearing students' answers selectively.

Teacher: the metals will be the elements located in the lower left corner of the PSCE.

The teacher emphasizes that all elements located below the B - At diagonal, even those with 4 electrons (Ge, Sn, Pb), 5 electrons (Sb, Bi), 6 electrons (Po) on the outer layer, will be metals in PSCE, since they have a large radius.

Thus, 85 out of 109 elements of PSChE are metals. Slide number 7

Teacher: the position of the element in the PSCE reflects the atomic structure of the element. Using the tables that you received at the beginning of the lesson, we characterize the structure of the sodium atom by its position in the PSCE.
Demonstration of slide 8.

What is a sodium atom? Look at the approximate model of the sodium atom, in which you can see the nucleus and electrons moving in orbits.

Demonstration of Slide 9.Sodium atom model.

Let me remind you how a diagram of the electronic structure of an atom of an element is drawn up.

Demonstration of slide 10.You should have the following diagram of the electronic structure of the sodium atom.

Slide 11. Task 2. Make a diagram of the electronic structure of the calcium and aluminum atom in the notebook yourself, following the example with the sodium atom.

The teacher checks the work in the notebook.

What conclusion can be drawn about the electronic structure of metal atoms?

On the external energy level, 1-3 electrons. We remember that entering into chemical compounds, atoms strive to restore the full 8-electron shell of the external energy level. For this, metal atoms easily donate 1-3 electrons from the external level, turning into positively charged ions. At the same time, they show restorative properties.

Demonstration of slide 12. Metals - these are chemical elements, the atoms of which donate electrons of the outer (and sometimes pre-outer) electronic layer, turning into positive ions. Metals are reducing agents. This is due to the small number of electrons in the outer layer, the large radius of the atoms, as a result of which these electrons are weakly confined to the nucleus.

Let's consider simple substances - metals.

Demonstration of slide 13.

First, we summarize information about the type of chemical bond formed by metal atoms and the structure of the crystal lattice

1. a relatively small number of electrons simultaneously bind many nuclei, the bond is delocalized;
2. valence electrons move freely over the entire piece of metal, which is generally electrically neutral;
3. the metallic bond does not have directionality and saturation.

Demonstration

Slide 14 " Types of crystal lattices of metals»

Slide 15 Video of the crystal lattice of metals.

The students conclude that in accordance with this particular structure, metals are characterized by general physical properties.

The teacher emphasizes that the physical properties of metals are determined precisely by their structure.

Slide 16 The properties of metals are determined by the structure of their atoms.

a) hardness - all metals except mercury, solids under normal conditions. The mildest are sodium, potassium. They can be cut with a knife; the hardest chrome - scratches glass (demo).

b) density - metals are divided into light (5g / cm) and heavy (more than 5g / cm) (demonstration).

c) fusibility - metals are divided into fusible and refractory (demonstration).

G) electrical conductivity, thermal conductivitymetals due to their structure. Chaotically moving electrons under the action of an electric voltage acquire a directional movement, as a result of which an electric current arises.

As the temperature rises, the amplitude of the motion of atoms and ions located in the nodes of the crystal lattice increases sharply, and this interferes with the movement of electrons, and the electrical conductivity of metals decreases.

It should be noted that in some non-metals, with an increase in temperature, the electrical conductivity increases, for example, in graphite, while with an increase in temperature, some covalent bonds are destroyed, and the number of freely moving electrons increases.

e) metallic luster- electrons filling the interatomic space reflect light rays, and do not transmit, like glass.

Therefore, all metals in the crystalline state have a metallic luster. For most metals, all rays of the visible part of the spectrum are equally scattered, so they have a silvery-white color. Only gold and copper absorb to a large extent short wavelengths and reflect long wavelengths of the light spectrum, therefore they have yellow light. The most brilliant metals are mercury, silver, palladium. In the powder, all metals, except for AI and Mg, lose their luster and have a black or dark gray color.

f) plasticity ... Mechanical action on a crystal with a metal lattice only causes displacement of atomic layers and is not accompanied by bond breaking, and therefore the metal is characterized by high plasticity.

IV. Consolidation of the studied material.

Teacher: we examined the structure and physical properties of metals, their position in the periodic table of chemical elements of D.I. Mendeleev. Now, to consolidate, we suggest performing a test.

Slides 15-16-17.

1) Electronic formula of calcium.

1. a) 1S 2 2S 2 2P 6 3S 1
2. b) 1S 2 2S 2 2P 6 3S 2
3. c) 1S 2 2S 2 2P 6 3S 2 3S 6 4S 1
4. d) 1S 2 2S 2 2P 6 3S 2 3P 6 4S 2

2) Electronic formula 1S 2 2S 2 2P 6 3S 2 3P 6 4S 2 has an atom:

1. a) Na
2. b) Ca
3. c) Сu
4. d) Zn

3) Electrical conductivity, metallic luster, plasticity, density of metals are determined by:

1. a) the mass of metal
2. b) the melting point of metals
3. c) the structure of metal atoms
4. d) the presence of unpaired electrons

4) Metals, when interacting with non-metals, exhibit properties

1. a) oxidative;
2. b) restorative;
3. c) both oxidizing and reducing;
4. d) do not participate in redox reactions;

5) In the periodic table, typical metals are located in:

1. a) upper part;
Vi. Homework.

The structure of metal atoms, their physical properties




Position of metals in the periodic table

If we draw a diagonal from boron to astatine in the table of D.I. Elements located near the diagonal have dual properties: in some of their compounds they behave like metals; in some - as non-metals.

The structure of metal atoms

In periods and main subgroups, there are regularities in the change in metallic properties.

Many metal atoms have 1, 2, or 3 valence electrons, for example:

Na (+ 11): 1S2 2S22p6 3S1

Ca (+ 20): 1S2 2S22p6 3S23p63d0 4S2

Alkali metals (group 1, main subgroup): ... nS1.

Alkaline earth (group 2, main subgroup): ... nS2.

The properties of metal atoms are periodically dependent on their location in DI Mendeleev's table.

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a - copper; b - magnesium; c - α-modification of iron

Metal atoms tend to donate their outer electrons. In a piece of metal, ingot or metal product, the metal atoms give up external electrons and send them to this piece, ingot or product, thus turning into ions. The "torn off" electrons move from one ion to another, temporarily reunite with them into atoms, torn off again, and this process occurs continuously. Metals have a crystal lattice, in the nodes of which there are atoms or ions (+); between them are free electrons (electron gas). The communication scheme in metal can be displayed as follows:

М0 ↔ nē + Мn +,

atom - ion

where n Is the number of external electrons participating in the bond (y Na - 1 ē, at Ca - 2 ē, at Al - 3 ē).

This type of bond is observed in metals - simple substances - metals and in alloys.

A metallic bond is a bond between positively charged metal ions and free electrons in the crystal lattice of metals.

The metallic bond has some similarity with the covalent bond, but also some difference, since the metal bond is based on the socialization of electrons (similarity), all atoms take part in the socialization of these electrons (difference). That is why crystals with a metallic bond are ductile, electrically conductive and have a metallic luster. However, in the vapor state, metal atoms are linked by a covalent bond, metal pairs are composed of individual molecules (monoatomic and diatomic).

General characteristics of metals

The ability of atoms to donate electrons (oxidize)	← Increasing
Interaction with atmospheric oxygen	Oxidizes quickly at ambient temperatures	Oxidize slowly at normal temperature or when heated	Do not oxidize
Interaction with water	At normal temperatures, H2 is released and hydroxide is formed	When heated, H2 is released	H2 is not displaced from water
5interaction with acids	Displace H2 from dilute acids	Does not displace H2 from dilute acids
React with conc. and decomp. HNO3 and with conc. H2SO4 when heated	Do not react with acids
Being in nature	Only in connections	In connections and in free form	Mostly loose
Methods of obtaining	Electrolysis of melts	Reduction with coal, carbon monoxide (2), alumothermy, or electrolysis of aqueous solutions of salts
The ability of ions to attach electrons (recover)	Li K Ca Na Mg Al Mn Zn Cr Fe Ni Sn Pb (H) Cu Hg Ag Pt Au
Increasing →

Electrochemical series of metal voltages. Physical and chemical properties of metals

General physical properties of metals

The general physical properties of metals are determined by the metallic bond and the metallic crystal lattice.

Malleability, ductility

Mechanical action on a metal crystal causes a displacement of the layers of atoms. Since the electrons in the metal move throughout the crystal, no breaking of bonds occurs. Plasticity decreases in a row Au, Ag, Cu, Sn, Pb, Zn, Fe... Gold, for example, can be rolled into sheets no more than 0.001 mm thick, which are used for gilding various items. Aluminum foil appeared relatively recently and earlier tea, chocolate was forged into tin foil, which was called stanyol. However, Mn and Bi do not have ductility: these are brittle metals.

Metallic luster

Metallic luster, which in the powder is lost by all metals, except Al and Mg... The brightest metals are Hg(the famous "Venetian mirrors" were made from it in the Middle Ages), Ag(now modern mirrors are made from it with the help of the reaction of the "silver mirror"). By color (conventionally), ferrous and non-ferrous metals are distinguished. Among the latter, we will single out precious ones - Au, Ag, Pt. Gold is the metal of jewelers. It was on its basis that wonderful Faberge Easter eggs were made.

Ringing

Metals ring, and this property is used to make bells (remember the Tsar Bell in the Moscow Kremlin). The most sonorous metals are Au, Ag, Ci. Copper rings with a thick, humming ring - a crimson ring. This is a figurative expression not in honor of the raspberry berry, but in honor of the Dutch city of Malina, where the first church bells were melted. Later in Russia, Russian craftsmen began to cast bells of even better quality, and residents of cities and towns donated gold and silver jewelry so that the bell cast for churches would sound better. In some Russian pawnshops, the authenticity of gold rings accepted for commission was determined by the ringing of a gold wedding ring suspended from a woman's hair (a very long and clear high-pitched sound is heard).

Under normal conditions, all metals except mercury Hg are solids. The hardest metal is chromium Cr, which scratches glass. The softest are alkali metals, they are cut with a knife. Alkali metals are stored with great precautions - Na - in kerosene, and Li - in petroleum jelly because of its lightness, kerosene - in a glass jar, a jar - in asbestos chips, asbestos - in a tin can.

Electrical conductivity

The good electrical conductivity of metals is explained by the presence of free electrons in them, which, under the influence of even a small potential difference, acquire a directional movement from the negative to the positive pole. As the temperature rises, the vibrations of atoms (ions) intensify, which makes it difficult for the directional movement of electrons and thereby leads to a decrease in electrical conductivity. At low temperatures, the vibrational motion, on the contrary, greatly decreases and the electrical conductivity increases sharply. Metals exhibit superconductivity near absolute zero. Ag, Cu, Au, Al, Fe have the highest electrical conductivity; worst conductors - Hg, Pb, W.

Thermal conductivity

Under normal conditions, the thermal conductivity of metals changes in basically the same sequence as their electrical conductivity. Thermal conductivity is due to the high mobility of free electrons and the vibrational motion of atoms, due to which there is a rapid equalization of temperature in the mass of the metal. The highest thermal conductivity is in silver and copper, the lowest is in bismuth and mercury.

Density

The density of metals is different. It is the less, the less the atomic mass of the metal element and the larger the radius of its atom. The lightest metal is lithium (density 0.53 g / cm3), the heaviest is osmium (density 22.6 g / cm3). Metals with a density of less than 5 g / cm3 are called light, the rest are called heavy.

The melting and boiling points of metals are varied. The most low-melting metal - mercury (boiling point = -38.9 ° С), cesium and gallium - melt at 29 and 29.8 ° С, respectively. Tungsten is the most refractory metal (bp = 3390 ° C).

The concept of allotropy of metals on the example of tin

Some metals have allotropic modifications.

For example, tin is distinguished into:

· Α-tin, or gray tin ("tin plague" - the transformation of ordinary β-tin into α-tin at low temperatures caused the death of R. Scott's expedition to the South Pole, who lost all fuel, as it was stored in sealed tanks tin), stable at t<14°С, серый порошок.

· Β-tin, or white tin (t = 14 - 161 ° C) is a very soft metal, but harder than lead, amenable to casting and soldering. It is used in alloys such as tinplate (tinned iron).

Electrochemical series of voltages of metals and its two rules

The arrangement of atoms in a row according to their reactivity can be represented as follows:

Li, K, Ca, Na, Mg, Al, Mn, Zn, Fe, Ni, Sn, Pb,H2 , Сu, Hg, Ag, Pt, Au.

The position of an element in the electrochemical series shows how easily it forms ions in an aqueous solution, i.e., its reactivity. The reactivity of elements depends on the ability to accept or donate electrons involved in the formation of a bond.

1st rule of a series of voltages

If the metal is in this row before hydrogen, it is able to displace it from acid solutions, if after hydrogen, then not.

For instance, Zn, Mg, Al gave a substitution reaction with acids (they are in the series of voltages up to H), a Cu no (she after H).

2nd rule of a series of voltages

If the metal is in the series of stresses up to the metal of the salt, then it is able to displace this metal from the solution of its salt.

For example, CuSO4 + Fe = FeSO4 + Cu.

In such cases, the position of the metal before or after hydrogen it may not matter, it is important that the reacting metal precedes the metal forming the salt:

Cu + 2AgNO3 = 2Ag + Cu (NO3) 2.

General chemical properties of metals

In chemical reactions, metals are reducing agents (they donate electrons).

Interaction with simple substances.

1. With halogens, metals form salts - halides:

Mg + Cl2 = MgCl2;

Zn + Br2 = ZnBr2.

2. Metals form oxides with oxygen:

4Na + O2 = 2 Na2O;

2Cu + O2 = 2CuO.

3. With sulfur, metals form salts - sulfides:

4. With hydrogen, the most active metals form hydrides, for example:

Ca + H2 = CaH2.

5.with carbon, many metals form carbides:

Ca + 2C = CaC2.

Interaction with complex substances

1. Metals at the beginning of a series of voltages (from lithium to sodium), under normal conditions, displace hydrogen from water and form alkalis, for example:

2Na + 2H2O = 2NaOH + H2.

2. Metals located in the series of voltages up to hydrogen interact with dilute acids (НCl, Н2SO4, etc.), as a result of which salts are formed and hydrogen is released, for example:

2Al + 6HCl = 2AlCl3 + 3H2.

3. Metals interact with solutions of salts of less active metals, as a result of which a salt of a more active metal is formed, and less active metal is released in a free form, for example:

CuSO4 + Fe = FeSO4 + Cu.

Metals in nature.

Finding metals in nature.

Most metals are found in nature in the form of various compounds: active metals are found only in the form of compounds; low-activity metals - in the form of compounds and in free form; noble metals (Ag, Pt, Au ...) in free form.

Native metals are usually found in small quantities in the form of grains or inclusions in rocks. Rarely, there are also quite large pieces of metal - nuggets. Many metals in nature exist in a bound state in the form of chemical natural compounds - minerals... Very often these are oxides, for example, iron minerals: red iron ore Fe2O3, brown iron ore 2Fe2O3 ∙ 3H2O, magnetic iron ore Fe3O4.

Minerals are part of rocks and ores. Ores are called natural formations containing minerals, in which metals are present in quantities that are technologically and economically suitable for the production of metals in industry.

According to the chemical composition of the mineral included in the ore, there are oxide, sulfide and other ores.

Usually, before obtaining metals from ore, it is preliminarily enriched - empty rock, impurities are separated, as a result, a concentrate is formed, which serves as a raw material for metallurgical production.

Methods for obtaining metals.

The production of metals from their compounds is the task of metallurgy. Any metallurgical process is a process of reduction of metal ions with the help of various reducing agents, as a result of which metals are obtained in a free form. Depending on the method of carrying out the metallurgical process, pyrometallurgy, hydrometallurgy and electrometallurgy are distinguished.

Pyrometallurgy Is the production of metals from their compounds at high temperatures using various reducing agents: carbon, carbon monoxide (II), hydrogen, metals (aluminum, magnesium), etc.

Examples of metal recovery

ZnO + C → Zn + CO2;

Carbon monoxide:

Fe2O3 + 3CO → 2Fe + 3CO2;

Hydrogen:

WO3 + 3H2 → W + 3H2O;

CoO + H2 → Co + H2O;

Aluminum (alumothermy):

4Al + 3MnO2 → 2Al2O3 + 3Mn;

Cr2O3 + 2Al = 2Al2O3 + 2Cr;

Magnesium:

TiCl4 + 2Mg = Ti + 2MgCl2.

Hydrometallurgy- This is the production of metals, which consists of two processes: 1) the natural compound of the metal dissolves in acid, resulting in a solution of the metal salt; 2) from the resulting solution, this metal is displaced by a more active metal. For instance:

1.2CuS + 3О2 = 2CuO + 2SО2.

CuO + H2SO4 = CuSO4 + H2O.

2. CuSO4 + Fe = FeSO4 + Cu.

Electrometallurgy- This is the production of metals by electrolysis of solutions or melts of their compounds. Electric current plays the role of a reducing agent in the electrolysis process.

General characteristics of the metals of the IA group.

The metals of the main subgroup of the first group (IA-group) include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr). These metals are called alkali metals, since they and their oxides form alkalis when interacting with water.

Alkali metals are s-elements. On the outer electron layer, metal atoms have one s-electron (ns1).

Potassium, sodium - simple substances



Alkali metals in ampoules:
a - cesium; b - rubidium; c - potassium; g - sodium

Basic information about the elements of the IA group

	Li lithium	Na sodium	K potassium	Rb rubidium	Cs cesium	Fr france
Atomic number
Oxidation state
Basic natural compounds	Li2O · Al2O3 · 4SiO2 (spodumene); LiAl (PO4) F, LiAl (PO4) OH (amblygonite)	NaCl (table salt); Na2SO4 10H2O (Glauber's salt, mirabiite); КCl NaCl (sylvite)	KCl (sylvinite), KCl NaCl (sylvinite); K (potassium feldspar, orthogonal); KCl MgCl2 6H2O (carnallite) - found in plants	As an isoamorphic impurity in potassium minerals - sylvinite and carnallite	4Cs2O · 4Al2O3 · 18 SiO2 · 2H2O (semi-cyt); companion of potassium minerals	Α-decay product of actinium

Physical properties

Potassium and sodium are soft silvery metals (cut with a knife); ρ (K) = 860 kg / m3, Tm (K) = 63.7 ° C, ρ (Na) = 970 kg / m3, Tm (Na) = 97.8 ° C. They have high heat and electrical conductivity, paint the flame in characteristic colors: K - in a pale violet color, Na - in yellow.

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Interaction with complex substances:

1.2Na + 2H2O → 2NaOH + H2.

2. 2Na + Na2О2 → 2Na2О.

3.2Na + 2НCl → 2NaCl + Н2.

Pulp and paper industry "href =" / text / category / tcellyulozno_bumazhnaya_promishlennostmz / "rel =" bookmark "> production of paper, artificial fabrics, soap, for cleaning oil pipelines, in the production of artificial fibers, in alkaline batteries.

Finding metal compoundsIAgroups in nature.

Salt ― NaCl- sodium chloride, NaNO3- sodium nitrate (Chilean nitrate), Na2CO3- sodium carbonate (soda), NaHCO3- sodium bicarbonate (baking soda), Na2SO4- sodium sulfate, Na2SO4 10H2O- Glauber's salt, KCl- potassium chloride, KNO3- potassium nitrate (potassium nitrate), K2SO4- potassium sulfate, К2СО3- potassium carbonate (potash) - crystalline ionic substances, almost all soluble in water. Sodium and potassium salts exhibit the properties of medium salts:

2NaCl (solid) + Н2SO4 (conc.) → Na2SO4 + 2НCl;

КCl + AgNo3 → KNO3 + AgCl ↓;

Na2CO3 + 2HCl → NaCl + CO2 + H2O;

K2CO3 + H2O ↔ KHCO3 + KOH;

СО32- + Н2О ↔ HCO3- + OH - (alkaline medium, pH< 7).

Table salt crystals

Salt mine

Na2CO3 serves for the production of paper, soap, glass;

NaHCO3- in medicine, cooking, in the production of mineral waters, in fire extinguishers;

К2СО3- to obtain liquid soap and glass;

Potash - potassium carbonate

NaNO3, KNO3, KCl, K2SO4- the most important potash fertilizers.

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Sea salt contains 90-95% NaCl (sodium chloride) and up to 5% of other minerals: magnesium salts, calcium salts, potassium salts, manganese salts, phosphorus salts, iodine salts, etc. All together over 40 useful elements of the periodic table - all this exists in sea water.

Dead Sea

There is something extraordinary, almost fantastic in him. In the eastern lands, even the tiniest trickle of moisture is a source of life, gardens bloom there, cereals ripen. But this water kills all living things.

Many peoples have visited these shores: Arabs, Jews, Greeks, Romans; each of them called this huge lake in their own language, but the meaning of the name was the same: dead, perilous, lifeless.



We stood on a deserted shore, the dull look of which evoked sadness: a dead land - no grass, no birds. On the other side of the lake, reddish mountains rose steeply from the green water. Bare, wrinkled slopes. It seemed that some force tore off their natural cover, and the muscles of the earth were exposed.

We decided to take a dip, but the water turned out to be cold, we just washed ourselves with thick water, flowing like a cool brine. After a few minutes, the face and hands were covered with a white coating of salt, and an unbearably bitter taste remained on the lips, from which it was impossible to get rid of it for a long time. You cannot drown in this sea: thick water itself keeps a person on the surface.

Sometimes a fish swims from Jordan to the Dead Sea. She dies in a minute. We found one such fish washed ashore. She was as hard as a stick in a tough, salty shell.
This sea can become a source of wealth for the people. After all, this is a gigantic storehouse of mineral salts.




Each liter of Dead Sea water contains 275 grams of potassium, sodium, bromine, magnesium, calcium salts. Mineral reserves are estimated here at 43 billion tons. Bromine and potash can be mined extremely cheaply, and there is nothing to limit the scale of production. The country possesses huge reserves of phosphates, which are in great demand on the world market, and their negligible amount is mined.

General characteristics of the elements of the IIA-group.

The metals of the main subgroup of the second group (IIA-group) include beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra). These metals are called alkaline earth metals, since their hydroxides Ме (ОН) 2 have alkaline properties, and their oxides МеО are similar in their refractoriness to the oxides of heavy metals, formerly called "earths".

Alkaline earth metals are s-elements. On the outer electron layer, metal atoms have two s-electrons (ns2).

Basic information about the elements of IIA-group

	Be beryllium	Mg magnesium	Ca calcium	Sr strontium	Ba barium	Ra radium
Atomic number
The structure of the outer electron shells of atoms	where n = 2, 3, 4, 5, 6, 7, n is the number of the period
Oxidation state
Basic natural compounds	3BeO Al2O3 6SiO2 (beryl); Be2SiO4 (phenakite)	2MgO SO2 (olivine); MgCO3 (magnesite); MgCO3 CaCO3 (dolomite); MgCl2 KCl 6H2O (carnallite)	CaCO3 (calcite), СaF2― fluorite, СaO · Al2O3 · 6SiO2 (anorthite); CaSO4 2H2O (gypsum); MgCO3 CaCO3 (dolomite), Ca3 (PO4) 2 - phosphorite, Ca5 (PO4) 3X (X = F, Cl, OH) - apatite	SrCO3 (stron cyanite), SrSO4 (celestine)	BaCO3 (baterite) BaSO4 (barite, heavy spar)	As part of uranium ores

Alkaline earth- light silver-white metals. Strontium has a golden hue, much harder than alkali metals. Barium is similar in softness to lead. In air at ordinary temperatures, the surface of beryllium and magnesium is covered with a protective oxide film. Alkaline earth metals actively interact with atmospheric oxygen, so they are stored under a layer of kerosene or in sealed vessels, like alkali metals.

Calcium is a simple substance

Physical properties

Natural calcium is a mixture of stable isotopes. The most common calcium is 97%). Calcium is a silvery white metal; ρ = 1550 kg / m3, Tm = 839 ° C. Colors the flame orange-red.

Chemical properties

Interaction with simple substances (non-metals):

1.With halogens: Ca + Cl2 → CaCl2 (calcium chloride).

2.With carbon: Ca + 2C → CaC2 (calcium carbide).

3. With hydrogen: Ca + H2 → CaH2 (calcium hydride).

Salt: CaCO3 calcium carbonate is one of the most widespread compounds on Earth: chalk, marble, limestone. The most important of these minerals is limestone. He himself is an excellent building stone, in addition, he is a raw material for producing cement, slaked lime, glass, etc.

Lime crushed stone strengthens roads, and powder reduces soil acidity.

Natural chalk represents the remains of ancient animal shells. It is used as school crayons, in toothpastes, for the production of paper and rubber.

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Physical properties

Iron is a silvery-white or gray metal, solid, with high ductility, heat and electrical conductivity, refractory; ρ = 7874 kg / m3, Tm = 1540 ° C. Unlike other metals, iron is capable of magnetization, it has ferromagnetism.

Chemical properties

Iron interacts with both simple and complex substances.

Interaction of iron with oxygen



a) when heated (combustion), b) when n. at. (corrosion)

Iron chemical properties

Under n. at.	When heated
Reaction	3FeSO4 + 2K3 = Fe32 ↓ + 3K2SO4 (turbulene blue - dark blue sediment).	1. 4FeCl3 + 3K4 = Fe43 ↓ + 12KCl (Prussian blue - dark blue precipitate). 2. FeCl3 + 3NH4CNS ⇆ Fe (CNS) 3 + 3NH4Cl (blood-red Fe thiocyanate + ammonia).

The biological role of iron

Biochemists reveal the huge role of iron in the life of plants, animals and humans. As part of hemoglobin, iron causes the red color of this substance, which, in turn, determines the color of the blood. The body of an adult contains 3 g of iron, of which 75% are part of hemoglobin, due to which the most important biological process, respiration, is carried out. Iron is also essential for plants. It participates in the oxidative processes of protoplasm, during plant respiration and in the formation of chlorophyll, although it is not itself a part of it. Iron has long been used in medicine to treat anemia, with exhaustion, loss of strength.