What group are the alkali metals in? Alkali metals

Alkali metals.

Alkali metals are elements of the main subgroup of group I of D. I. Mendeleev’s Periodic Table of Chemical Elements:

lithium Li, sodium Na, potassium K, rubidium Rb, cesium Cs and francium Fr.

These metals are called alkaline metals because most of their compounds are soluble in water. In Slavic, “leach” means “dissolve,” which determined the name of this group of metals. When alkali metals are dissolved in water, soluble hydroxides called alkalis are formed.

Main characteristics of alkali metals: In the Periodic Table they come immediately after inert gases, therefore, the peculiarity of the structure of alkali metal atoms is that they contain one electron at a new energy level: their electron configuration is ns1.

The valence electrons of alkali metals can be easily removed because it is energetically favorable for the atom to give up an electron and acquire a noble gas configuration.

Therefore, all alkali metals are characterized by reducing properties. This is confirmed by the low values ​​of their ionization potentials (the ionization potential of the cesium atom is one of the lowest) and electronegativity (EO).
Below is a table of properties of alkali metals:

All metals in this subgroup have a silvery-white color.(except for silver-yellow cesium), they are very soft and can be cut with a scalpel. Lithium, sodium and potassium are lighter than water and float on its surface, reacting with it.

Alkali metals occur in nature in the form of compounds containing singly charged cations.

Many minerals contain metals of the main subgroup of group I. For example, orthoclase, or feldspar, consists of potassium aluminosilicate K2, a similar mineral containing sodium - albite - has the composition Na2. Sea water contains chloride sodium NaCl, and in the soil - potassium salts - sylvin KCl, sylvinite NaCl. KCl, carnallite KCl. MgCl2. 6H2O, polyhalite K2SO4. MgSO4. CaSO4. 2H2O.

Chemical properties of alkali metals
Due to the high chemical activity of alkali metals in relation to water, oxygen, and nitrogen, they are stored under a layer of kerosene. To carry out a reaction with an alkali metal, a piece the right size carefully cut with a scalpel under a layer of kerosene, in an argon atmosphere the surface of the metal is thoroughly cleaned of the products of its interaction with air, and only then the sample is placed in a reaction vessel.

1. Interaction with water. Important property of alkali metals- their high activity in relation to water. Lithium reacts most calmly (without explosion) with water:

When a similar reaction is carried out, sodium burns with a yellow flame and a small explosion occurs. Potassium is even more active: in this case the explosion is much stronger, and the flame is colored purple.
2. Interaction with oxygen. The combustion products of alkali metals in air have different compositions depending on the activity of the metal.

Only lithium burns in air to form an oxide of stoichiometric composition:

When sodium burns, Na2O2 peroxide is mainly formed with a small admixture of NaO2 superoxide:

The combustion products of potassium, rubidium and cesium contain mainly superoxides:

To obtain sodium and potassium oxides, mixtures of hydroxide, peroxide or superoxide with an excess of metal are heated in the absence of oxygen:

The following pattern is characteristic of oxygen compounds of alkali metals: as the radius of the alkali metal cation increases, the stability of oxygen compounds containing peroxide ion O22 and superoxide ion O2- increases.

Heavy alkali metals are characterized by the formation of fairly stable ozonides with the composition EO3. All oxygen compounds have different colors, the intensity of which deepens in the series from Li to Cs:

Alkali metal oxides have all the properties inherent in basic oxides: they react with water, acid oxides and acids:

Peroxides and superoxides exhibit the properties of strong oxidizing agents:

Peroxides and superoxides interact intensively with water, forming hydroxides:

3. Interaction with other substances. Alkali metals react with many nonmetals. When heated, they combine with hydrogen to form hydrides, with halogens, sulfur, nitrogen, phosphorus, carbon and silicon to form, respectively, halides, sulfides, nitrides, phosphides, carbides and silicides:

When heated, alkali metals are capable of reacting with other metals, forming intermetallic compounds. Alkali metals react actively (explosively) with acids.

Alkali metals dissolve in liquid ammonia and its derivatives - amines and amides:

When dissolved in liquid ammonia, an alkali metal loses an electron, which is solvated by ammonia molecules and gives the solution a blue color. The resulting amides are easily decomposed by water to form alkali and ammonia:

Alkali metals react with organic substances, alcohols (forming alcoholates) and carboxylic acids(with the formation of salts):

4. Qualitative determination of alkali metals. Since the ionization potentials of alkali metals are small, when the metal or its compounds are heated in a flame, the atom is ionized, coloring the flame a certain color:

Preparation of alkali metals
1. To obtain alkali metals, they mainly use electrolysis of melts of their halides, most often chlorides that form natural minerals:

cathode: Li+ + e → Li
anode: 2Cl- — 2e → Cl2
2. Sometimes, to obtain alkali metals, electrolysis of melts of their hydroxides is carried out:

Cathode: Na+ + e → Na
anode: 4OH- – 4e → 2H2O + O2
Since alkali metals are electrochemical series voltages are to the left of hydrogen, then their electrolytic production from salt solutions is impossible; in this case, the corresponding alkalis and hydrogen are formed.

Alkali metal compounds. Hydroxides

Alkali metals- these are the elements of the 1st group of the periodic table of chemical elements (according to the outdated classification - elements of the main subgroup of group I): lithium Li, sodium Na, potassium K, rubidium Rb, cesium Cs, France Fr, and despondent Uue. When alkali metals dissolve in water, soluble hydroxides are formed, called alkalis.

Chemical properties of alkali metals

Due to the high chemical activity of alkali metals towards water, oxygen, and sometimes even nitrogen (Li, Cs), they are stored under a layer of kerosene. To carry out a reaction with an alkali metal, a piece of the required size is carefully cut off with a scalpel under a layer of kerosene, the surface of the metal is thoroughly cleaned in an argon atmosphere from the products of its interaction with air, and only then the sample is placed in the reaction vessel.

1. Interaction with water. An important property of alkali metals is their high activity towards water. Lithium reacts most calmly (without explosion) with water:

When a similar reaction is carried out, sodium burns with a yellow flame and a small explosion occurs. Potassium is even more active: in this case, the explosion is much stronger, and the flame is colored purple.

2. Interaction with oxygen. The combustion products of alkali metals in air have different compositions depending on the activity of the metal.

· Only lithium burns in air to form an oxide of stoichiometric composition:

· When burning sodium mainly Na 2 O 2 peroxide is formed with a small admixture of NaO 2 superoxide:

· In combustion products potassium, rubidium And cesium contains mainly superoxides:

To obtain sodium and potassium oxides, mixtures of hydroxide, peroxide or superoxide with an excess of metal are heated in the absence of oxygen:

The following pattern is characteristic of oxygen compounds of alkali metals: as the radius of the alkali metal cation increases, the stability of oxygen compounds containing peroxide ion O 2 2− and superoxide ion O 2− increases.

Heavy alkali metals are characterized by the formation of fairly stable ozonides composition of EO 3. All oxygen compounds have different colors, the intensity of which deepens in the series from Li to Cs:

Alkali metal oxides have all the properties of basic oxides: they react with water, acidic oxides and acids:

Peroxides And superoxides exhibit the properties of strong oxidizing agents:

Peroxides and superoxides interact intensively with water, forming hydroxides:

3. Interaction with other substances. Alkali metals react with many nonmetals. When heated, they combine with hydrogen to form hydrides, with halogens, sulfur, nitrogen, phosphorus, carbon and silicon to form, respectively, halides, sulfides, nitrides, phosphides, carbides And silicides:

When heated, alkali metals are capable of reacting with other metals, forming intermetallic compounds. Alkali metals react actively (explosively) with acids.

Alkali metals dissolve in liquid ammonia and its derivatives - amines and amides:

When dissolved in liquid ammonia, an alkali metal loses an electron, which is solvated by ammonia molecules and gives the solution a blue color. The resulting amides are easily decomposed by water to form alkali and ammonia:

Alkali metals interact with organic substances, alcohols (to form alcoholates) and carboxylic acids (to form salts):

4. Qualitative determination of alkali metals. Since the ionization potentials of alkali metals are small, when the metal or its compounds are heated in a flame, the atom is ionized, coloring the flame a certain color:

Flame coloring with alkali metals
and their connections

Alkaline earth metals.

Alkaline earth metals- chemical elements II group periodic table of elements: beryllium, magnesium, calcium, strontium, barium and radium.

Physical properties

All alkaline earth metals are gray substances that are solid at room temperature. Unlike alkali metals, they are significantly harder and cannot be cut with a knife (with the exception of strontium). The density of alkaline earth metals with atomic number increases, although growth is clearly observed only starting with calcium, which has the lowest density among them (ρ = 1.55 g/cm³), the heaviest is radium, the density of which is approximately equal to the density of iron.

Chemical properties

Alkaline earth metals have electronic configuration external energy level ns², and are s-elements, along with the alkali metals. Having two valence electrons, alkaline earth metals easily give them up, and in all compounds they have an oxidation state of +2 (very rarely +1).

The chemical activity of alkaline earth metals increases with increasing serial number. Beryllium in its compact form does not react with oxygen or halogens, even at red heat temperatures (up to 600 °C; reactions with oxygen and other chalcogens require an even higher temperature, fluorine is an exception). Magnesium is protected by an oxide film at room temperature and higher temperatures (up to 650 °C) and does not oxidize further. Calcium oxidizes slowly and deeply at room temperature (in the presence of water vapor), and burns with slight heating in oxygen, but is stable in dry air at room temperature. Strontium, barium and radium quickly oxidize in air, giving a mixture of oxides and nitrides, so they, like alkali metals (and calcium), are stored under a layer of kerosene.

Oxides and hydroxides of alkaline earth metals tend to increase their basic properties with increasing atomic number: Be(OH) 2 is an amphoteric, insoluble hydroxide in water, but soluble in acids (and also exhibits acid properties in the presence of strong alkalis), Mg(OH) 2 - weak foundation, insoluble in water, Ca(OH) 2 - a strong but slightly soluble base in water, Sr(OH) 2 - more soluble in water than calcium hydroxide, a strong base (alkali) at high temperatures, close to the boiling point of water (100 °C), Ba(OH) 2 is a strong base (alkali), not inferior in strength to KOH or NaOH, and Ra(OH) 2 is one of the strongest alkalis, a very corrosive substance

Being in nature

All alkaline earth metals are present (in different quantities) in nature. Due to their high chemical activity, all of them are not found in a free state. The most common alkaline earth metal is calcium, the amount of which is 3.38% (by weight of the earth’s crust). It is slightly inferior to magnesium, the amount of which is 2.35% (of the mass of the earth’s crust). Barium and strontium are also common in nature, accounting for 0.05 and 0.034% of the mass of the earth's crust, respectively. Beryllium is a rare element, the amount of which is 6·10−4% of the mass of the earth's crust. As for radium, which is radioactive, it is the rarest of all alkaline earth metals, but it is small quantity always found in uranium ores. In particular, it can be isolated from there chemically. Its content is 1·10−10% (of the mass of the earth’s crust)

Aluminum.

Aluminum- an element of the main subgroup of the third group of the third period of the periodic system of chemical elements of D. I. Mendeleev, with atomic number 13. Denoted by the symbol Al(lat. Aluminum). Belongs to the group of light metals. The most common metal and the third most abundant chemical element in the earth's crust (after oxygen and silicon).

Simple substance aluminum- light, paramagnetic silver metal white, easy to mold, cast, and machine. Aluminum has high thermal and electrical conductivity and resistance to corrosion due to the rapid formation of strong oxide films that protect the surface from further interaction.

Aluminum was first obtained by the Danish physicist Hans Oersted in 1825 by the action of potassium amalgam on aluminum chloride followed by distillation of mercury. The modern production method was developed independently by the American Charles Hall and the Frenchman Paul Héroult in 1886. It consists of dissolving aluminum oxide Al 2 O 3 in a melt of cryolite Na 3 AlF 6 followed by electrolysis using consumable coke or graphite electrodes. This production method requires a lot of electricity, and therefore became popular only in the 20th century.

To produce 1000 kg of crude aluminum, 1920 kg of alumina, 65 kg of cryolite, 35 kg of aluminum fluoride, 600 kg of anode mass and 17 thousand kWh of DC electricity are required

Alkali metals - group inorganic substances, simple elements Periodic tables. They all have a similar atomic structure and, accordingly, similar properties. The group includes potassium, sodium, lithium, cesium, rubidium, francium and the theoretically described but not yet synthesized element ununennium. The first five substances exist in nature, francium is an artificially created, radioactive element. Alkali metals got their name from their ability to form alkalis in reaction with water.

All elements of the group are chemically active, therefore they are found on Earth only in the composition of various minerals, for example, rock, potassium, table salt, borax, feldspar, sea water, underground brines, Chilean nitrate. Francium often accompanies uranium ores; rubidium and cesium - minerals with sodium and potassium.

Properties

All representatives of the group are soft metals; they can be cut with a knife or bent by hand. Externally - shiny, white (except for cesium). Cesium has a golden sheen. Lightweight: sodium and potassium are lighter than water, lithium floats even in kerosene. Classic metals with good electrical and thermal conductivity. They burn, giving the flame a characteristic color, which is one of the analytical methods determine the type of metal. Low-melting, the most “refractory” is lithium (+180.5 °C). Cesium melts right in your hands at a temperature of +28.4 °C.

Activity in the group increases as it grows atomic mass: Li →Cs. Possess restorative properties, including in reaction with hydrogen. They exhibit a valence of -1. React violently with water (all except lithium - explosively); with acids and oxygen. They interact with non-metals, alcohols, aqueous ammonia and its derivatives, carboxylic acids, and many metals.

Potassium and sodium are biogenic elements, participate in the water-salt and acid-base balance of the human body, and are necessary for normal blood circulation and the functioning of many enzymes. Potassium is important for plants.

Our body also contains rubidium. It was found in blood, bones, brain, lungs. It has an anti-inflammatory, anti-allergic effect, slows down the reactions of the nervous system, strengthens the immune system, and has a positive effect on blood composition.

Precautions

Alkali metals are very dangerous and can ignite and explode simply from contact with water or air. Many reactions occur violently, so it is allowed to work with them only after careful instructions, using all precautions, wearing a protective mask and safety glasses.

Solutions of potassium, sodium and lithium in water are strong alkalis (potassium, sodium, lithium hydroxides); contact with skin results in deep, painful burns. Contact of alkalis, even low concentrations, in the eyes can lead to blindness. Reactions with acids, ammonia, and alcohols result in the release of flammable and explosive hydrogen.

Alkali metals are stored under a layer of kerosene or petroleum jelly in sealed containers. Manipulations with pure reagents are carried out in an argon atmosphere.

Care should be taken to dispose of residues from experiments with alkali metals. All metal residues must first be neutralized.

Application

Special (correctional)

secondary school– boarding school for the blind

and visually impaired children in Perm

Abstract completed

10th grade students

Ponomarev Oleg,

Korshunov Artem

Supervisor:

L.Yu. Zakharova,

chemistry teacher

Perm

Introduction

General characteristics elements of I A-group

4 – 10

1.1. History of the discovery and distribution of alkali metals in nature

4 – 5

5 - 6

6 – 8

8 – 9

9 – 10

Biological role of elements of group I A-group. Their use in medicine

11 – 17

Routes of entry of alkali metals into the human body

18 – 21

Practical work

22 – 23

Conclusions

24 – 25

Literature used

Introduction

The time has long come when everyone should think about their health and not only their own. We do not very often use the knowledge we acquire at school, for example in chemistry, in everyday life. However, this particular subject can become a source of knowledge about our health. Thanks to chemistry, we learn how the substances of our planet affect the vital processes of the body, and in general, human life itself, what is useful to us and in what quantities and, finally, what is harmful and to what extent.

The human body is a complex chemical system that cannot function independently, without connection with the environment. It has been proven that almost all chemical elements are present in a living organism: some are macroelements, while the content of others is negligible, these are microelements. The ways in which elements enter the body are different, and their influence on the body is varied, but each performs its own biological role.

It is impossible to study the meaning of each element within one work. We have chosen the very first group of chemical elements of D.I. Mendeleev’s periodic table.

Target of this study - study the biological role of alkali metals for the human body.

In this regard, we decided to find out the following questions for each metal of group IA:

general characteristics and structural features of the atoms of each element, as well as the properties of the substances they form;

presence of the element in the body;

the body's needs for it;

the effect of excess and deficiency of the element on human health;

natural sources;

methods for detecting an element.

1. General characteristics of elements of group I A-group

Period

Group

IN I A-group includes s-elements - alkali metals, which are extremely important for normal life animals and people. Highest value for organisms have the macroelements sodium and potassium.

3Li

11 Na

19K

37 Rb

55 Cs

87 Fr

1.1. History of discovery and distribution in nature

alkali metals

The name “alkali metals” is due to the fact that the hydroxides of the two main representatives of this group - sodium and potassium - have long been known as alkalis. From these alkalis, subjecting them to electrolysis in a molten state, G. Davy in 1807 for the first time received free potassium and sodium. J. Berzelius proposed calling element No. 11 sodium (from Arabic natrun- soda), and element No. 19, at Gilbert’s suggestion, was named potassium (from the Arabic alkali– alkali).

The remaining metals were isolated by scientists from the compounds later. Lithium was discovered by the Swedish chemist I. Arfvedson in 1817, and at the suggestion of J. Berzelius it was called lithium (from the Greek litos- stone), because Unlike potassium, which until then had only been found in plant ashes, it was found in stone.

Rubidium was isolated in 1861, cesium in 1860. Francium was obtained artificially in 1939. French researcher M. Pere during the decay of actinium, is a radioactive element.

Due to their very easy oxidation, alkali metals occur in nature exclusively in the form of compounds. Some of their natural compounds, in particular sodium and potassium salts, are quite widespread; they are found in many minerals, plants, and natural waters.

Sodium and potassium are common elements: the content of each of them in the earth's crust is approximately 2% by weight. Both metals are found in various minerals and silicate-type burrow rocks.

Sodium chloride NaCl is found in seawater and also forms powerful deposits rock salt in many places around the world. IN upper layers These deposits sometimes contain quite significant amounts of potassium, mainly in the form of chloride KCl or double salts with sodium and magnesium KCl ∙MgCl 2. However, large accumulations of potassium salts, which have industrial value, are rare. The most important of them are the Solikamsk deposits (sylvinite) in Russia, the Strassfurt deposits in Germany and the Alsatian deposits in France.

Deposits of sodium nitrate NaNO 3 are located in Chile. The water of many lakes contains Na 2 CO 3 soda. Finally, huge quantities of sodium sulfate Na 2 SO 4 are found in the Kara-Bogaz-Gol Bay of the Caspian Sea, where this salt is winter months settles in a thick layer on the bottom.

Significantly less common than sodium and potassium are lithium, rubidium and cesium. Lithium is most common, but minerals containing it rarely form large accumulations. Rubidium and cesium are contained in large quantities ah in some lithium minerals.

Francium is found in nature in insignificant quantities (there is hardly 500g of it on the entire globe); it is obtained artificially.

1.2. Structure and properties of alkali metal atoms

The electronic formula of the valence shell of alkali metal atoms is ns 1, i.e. the atoms of these elements each have one valence electron in the s sublevel of the outer energy level. Accordingly, the stable oxidation state of alkali metals is +1.

All elements of the IA group are very similar in properties, which is explained by the similar structure of not only the valence electron shell, but also the outer one (with the exception of lithium).

As the radius of an atom in the Li – Na – K – Rb – Cs – Fr group increases, the bond between the valence electron and the nucleus weakens. Accordingly, in this series the ionization energy of alkali metal atoms decreases.

Having one electron in the valence shells located on long distance from the nucleus, alkali metal atoms easily give up an electron. This causes low ionization energy. As a result of ionization, E + cations are formed, which have a stable electronic configuration of noble gas atoms.

The table shows some properties of alkali metal atoms.

Characteristic

3 Li

11 Na

1 9K

37 Rb

55 Cs

87 Fr

Valence electrons

2s 1

3s 1

4s 1

5s 1

6s 1

7s 1

Molar mass, g/mol

23,0

39,1

85,5

132,9

Metallic radius of an atom, pm

Crystal radius of an atom, pm

Ionization energy,

kJ/mol

Alkali metals are the most typical representatives of metals: metallic properties are especially pronounced in them.

1.3. Alkali metals are simple substances

Silvery-white soft substances (cut with a knife), with a characteristic shine on a freshly cut surface. When exposed to air, the shiny surface of the metal immediately becomes dull due to oxidation.

All of them are light and fusible, and, as a rule, their density increases from Li to Cs, and the melting point, on the contrary, decreases.

Characteristic

Li

Na

K

Rb

Cs

Fr

Density, g/cm 3

0,53

0,97

0,86

1,53

Hardness (diamond = 10)

Electrical conductivity (Hg = 1)

11,2

13,6

Melting point, C

Boiling point, C

1350

Standard electrode potential, V

3,05

2,71

2,92

2,93

2,92

Coordination number

4, 6

4, 6

6, 8

All alkali metals have negative standard redox potentials, large in absolute value. This characterizes them as very strong reducing agents. Only lithium is somewhat inferior to many metals in chemical activity.

Despite the similarity of properties, sodium and especially lithium differ from other alkali metals. The latter is primarily due to the significant difference in the radii of their atoms and the structure of the electron shells.

Alkali metals are among the most active in chemically elements. The chemical activity of alkali metals naturally increases with increasing atomic radius.

Li Na K Rb Cs Fr

Chemical activity increases

The radius of the atom increases

Alkali metals actively interact with almost all non-metals.

When interacting with oxygen lithium forms the oxide Li 2 O, and the remaining alkali metals form peroxides Na 2 O 2 and superoxides KO 2, RbO 2, CsO 2. For example:

4Li (t) + O 2 (g) = 2Li 2 O (t)

2Na (t) + O 2 (g) = Na 2 O 2 (t)

K (t) + O 2 (g) = KO 2 (t)

Alkali metals react actively with halogens, forming EG halides; with sulfur- with the formation of E 2 S sulfides. Alkali metals, with the exception of lithium, do not react directly with nitrogen.

2E(t) + Cl 2 (g) = 2ECl (t)

2E(t) + S (t) = E 2 S (t)

All alkali metals react directly with water, forming EON hydroxides - alkalis and reducing water to hydrogen:

2E (t) + 2H 2 O (l) = 2EON (r) + H 2 (g)

The intensity of interaction with water increases significantly in the Li-Cs series.

Regenerative capacity alkali metals is so great that they can even reduce hydrogen atoms, turning them into negatively charged H - ions. Thus, when heating alkali metals in a jet hydrogen their hydrides are obtained, for example:

2E(t) + N 2 (g) = 2EN

1.4. Application of alkali metals

Alkali metals and their compounds are widely used in technology.

Lithium is used in nuclear energy. In particular, the 6 Li isotope serves industrial source for the production of tritium, and the 7 Li isotope is used as a coolant in uranium reactors. Due to the ability of lithium to easily combine with hydrogen, nitrogen, oxygen, and sulfur, it is used in metallurgy to remove traces of these elements from metals and alloys.

Lithium and its compounds are also used as fuel for rockets. Lubricants containing lithium compounds retain their properties over a wide temperature range. Lithium is used in ceramics, glass and other industries chemical industry. In general, in terms of importance in modern technology this metal is one of the most important rare elements.

Cesium and rubidium are used to make solar cells. In these devices that convert radiant energy into energy electric current and based on the phenomenon of the photoelectric effect, the ability of cesium and rubidium atoms to split off valence electrons when metal is exposed to radiant energy.

The most important areas of application of sodium are nuclear energy, metallurgy, and the organic synthesis industry.

In nuclear energy, sodium and its alloy with potassium are used as liquid metal coolants. A sodium-potassium alloy containing 77.2% potassium is found in liquid state over a wide temperature range, has a high heat transfer coefficient and does not interact with most structural materials.

In metallurgy, a number of refractory metals are obtained using the sodium thermal method. In addition, sodium is used as an additive to strengthen lead alloys.

In the organic synthesis industry, sodium is used in the production of many substances. It also serves as a catalyst in the production of some organic polymers.

Potassium is one of the elements necessary for significant amount for plant nutrition. Although there is quite a lot of potassium salts in the soil, it is also carried away with some cultivated plants also a lot. Flax, hemp and tobacco carry away especially much potassium. To replenish the loss of potassium from the soil, it is necessary to add potassium fertilizers to the soil.

1.5. Alkali metal compounds

Oxides E 2 ABOUT- solids. They have pronounced basic properties: they interact with water, acids and acid oxides. For example:

E 2 O(t) + H 2 O(l) = 2EON (p)

Peroxides and superoxides E 2 ABOUT 2 and EO 2 alkali metals are strong oxidizing agents. Sodium peroxide and potassium superoxide are used in closed facilities ( submarines, spaceships) to absorb carbon dioxide and regenerate oxygen:

2Na 2 O 2 (t) + 2CO 2 (g) = 2Na 2 CO 3 (t) + O 2 (g)

4KO 2 (t) + 2CO 2 (g) = 2K 2 CO 3 (t) + 3O 2 (g)

Sodium peroxide is also used to bleach fabrics, wool, silk, etc.

Alkalis– hard, white, very hygroscopic crystalline substances, relatively fusible and highly soluble in water (with the exception of LiOH). Solid alkalis and their concentrated solutions have a corrosive effect on fabrics, paper and living tissues due to dehydration and alkaline hydrolysis of proteins. Therefore, working with them requires protective precautions. Due to their strong corrosive effect, these alkalis are called caustic (NaOH - caustic soda, caustic, KOH - caustic potassium).

Alkalies dissolve well in water with the release of a large amount of heat, exhibit pronounced properties of strong soluble bases: they interact with acids, acid oxides, salts, amphoteric oxides and hydroxides.

Caustic soda is used in large quantities to purify petroleum products. in the paper and textile industries, for the production of soap and fibers.

Caustic potassium is more expensive and is used less frequently. Its main area of ​​application is production liquid soap.

Alkali metal salts– solid crystalline substances of ionic structure. The most important of them are carbonates, sulfates, and chlorides.

Most alkali metal salts are highly soluble in water (with the exception of lithium salts: Li 2 CO 3, LiF, Li 3 PO 4).

With polybasic acids, alkali metals form both medium (E 2 SO 4, E 3 PO 4, E 2 CO 3, E 2 SO 3, etc.) and acidic (ENSO 4, EN 2 PO 4, E 2 NPO 4, ENSO 3, etc.) salts.

Na 2 CO 3 - sodium carbonate, forms crystalline hydrate Na 2 CO 3 ∙10H 2 CO 3, known as crystalline soda, which is used in the production of glass, paper, and soap. This is medium salt.

Better known in everyday life acid salt– sodium bicarbonate NaHCO 3, it is used in food industry(baking soda) and in medicine (baking soda).

K 2 CO 3 - potassium carbonate, technical name - potash, used in the production of liquid soap and for the preparation of refractory glass, and also as a fertilizer.

Na 2 SO 4 ∙10H 2 O – sodium sulfate crystalline hydrate, technical name Glauber’s salt, is used for the production of soda and glass, and also as a laxative.

NaCl - sodium chloride, or table salt, is the most important raw material in the chemical industry and is widely used in everyday life.

2. Biological role of s-elements of group IA. Their use in medicine

Chemical element, E

10 -4 %

0,08%

0,23%

10 -5 %

10 -4 %

Alkali metals in the form of various compounds are part of human and animal tissues.

Sodium and potassium are vital elements that are constantly present in the body and participate in metabolism. Lithium, rubidium and cesium are also constantly contained in the body, but their physiological and biochemical role is poorly understood. They can be classified as trace elements.

In the human body, alkali metals are found in the form of the E + cation.

Similarities electronic structure alkali metal ions, and, consequently, the physicochemical properties of the compounds are determined by the proximity of their effect on biological processes. Differences in electronic structure determine their different biological roles. On this basis, it is possible to predict the behavior of alkali metals in living organisms.

Thus, sodium and lithium accumulate in the extracellular fluid, and potassium, rubidium and cesium accumulate in the intracellular fluid. Lithium and sodium are especially close in biological action. For example, they are very similar in their enzyme-activating properties.

The similarity of the properties of sodium and lithium determines their interchangeability in the body. In this regard, with excessive introduction of sodium or lithium ions into the body, they are able to equivalently replace each other. This is the basis for the administration of sodium chloride in cases of lithium salt poisoning. In accordance with Le Chatelier's principle, the balance between sodium and lithium ions in the body shifts towards the elimination of Li + ions, which leads to a decrease in its concentration and the achievement of a therapeutic effect.

Rubidium and cesium are close in physical and chemical properties to potassium ions, so they behave in a similar way in living organisms. In the systems studied, potassium, rubidium and cesium are synergists, and with lithium they are antagonists. The similarity of rubidium and potassium is the basis for the introduction of potassium salts into the body in case of poisoning with rubidium salts.

Sodium and potassium, as a rule, are antagonists, but in some cases the similarity of many physicochemical properties determines their interchange in living organisms. For example, with an increase in the amount of sodium in the body, the excretion of potassium by the kidneys increases, i.e., hypokalemia occurs.

Lithium. The lithium content in the human body is about 70 mg (10 mmol). Lithium is one of the most valuable microelements, or, as they also call it, mini-metals. Lithium was once used to treat gout and eczema. And in 1971 An interesting message appeared in the Medical News magazine: in those areas where drinking water contains large number lithium, people are kinder and calmer, there are fewer rude people and brawlers among them, and there are significantly fewer mental illnesses. The psychotropic properties of this metal were revealed. Lithium began to be used for depression, hypochondria, aggressiveness and even drug addiction.

However, lithium can be both “good” and “evil”. There have been cases when, during injection treatment with lithium, a powerful metabolic disorder occurred, and serious consequences of this are inevitable.

Lithium compounds in higher animals are concentrated in the liver, kidneys, spleen, lungs, blood, and milk. The maximum amount of lithium is found in human muscles. The biological role of lithium as a trace element has not yet been fully elucidated.

It has been proven that at the level of cell membranes, lithium ions compete with sodium ions when entering cells. Obviously, the replacement of sodium ions in cells with lithium ions is associated with a greater covalency of lithium compounds, as a result of which they are better soluble in phospholipids.

It has been established that some lithium compounds have a positive effect on patients with manic depression. Absorbed from the gastrointestinal tract, lithium ions accumulate in the blood. When the concentration of lithium ions reaches 0.6 mmol/l and above, there is a decrease in emotional tension and a weakening of manic excitement. However, the content of lithium ions in the blood plasma must be strictly controlled. In cases where the concentration of lithium ions exceeds 1.6 mmol/l, negative phenomena are possible.

It is now known that in addition to psychotropic effects, lithium has properties to prevent sclerosis, heart disease, and to some extent diabetes and hypertension. It “helps” magnesium in its anti-sclerotic protection.

At the end of 1977 The results of studies conducted at the Krakow Hematology Clinic were published. The studies were devoted to the influence of lithium on hematopoietic system. It turned out that this microelement activates the action of bone marrow cells that have not yet died. The discovery made can play important role in the fight against blood cancer. Research is still ongoing. I would like to believe that their results will bring invaluable help to people.

Sodium. The sodium content in the human body weighing 70 kg is about 60 g (2610 mmol). Of this amount, 44% of sodium is in the extracellular fluid and 9% in the intracellular fluid.

The remaining amount of sodium is found in bone tissue, which is the site of deposition of the Na + ion in the body. About 40% of the sodium contained in bone tissue is involved in metabolic processes and due to this, the skeleton is either a donor or acceptor of sodium ions, which helps maintain a constant concentration of sodium ions in the extracellular fluid.

Sodium is the main extracellular ion. The human body contains sodium in the form of its soluble salts, mainly NaCl chloride, Na 3 PO 4 phosphate and NaHCO 3 bicarbonate.

Sodium is distributed throughout the body: in blood serum, cerebrospinal fluid, eye fluid, digestive juices, bile, kidneys, skin, bone tissue, lungs, brain.

Sodium ions play an important role in ensuring consistency internal environment human body, participates in maintaining constant osmotic pressure biofluids, ensures the acid-base balance of the body. Sodium ions are involved in the regulation of ion exchange and affect the functioning of enzymes. Together with potassium, magnesium, calcium, and chlorine ions, sodium ion is involved in the transmission nerve impulses through membranes nerve cells and maintains normal excitability of muscle cells.

When the sodium content in the body changes, dysfunctions of the nervous, cardiovascular and other systems, smooth and skeletal muscles. Sodium chloride NaCl serves as the main source of hydrochloric acid for gastric juice.

Sodium enters the human body mainly in the form of table salt NaCl. The body's true daily need for sodium is 1g, although the average consumption of this element reaches 4 - 7g.

Continuous excess consumption of NaCI contributes to the appearance of hypertension. In the body of a healthy person, a balance is maintained between the amount of sodium consumed and excreted. About 90% of sodium consumed is excreted in urine, and the rest in sweat and feces.

So, to summarize: sodium ions play an important role:

to ensure osmotic homeostasis

to ensure the acid-base balance of the body

in the regulation of water metabolism

in the work of enzymes

in the transmission of nerve impulses

in the work of muscle cells

Isotonic solutionNaCI (0,9%) for injection, it is administered subcutaneously, intravenously and in enemas for dehydration and intoxication, and is also used for washing wounds, eyes, nasal mucosa, as well as for dissolving various medications.

Hypertonic solutionsNaCI (3-5-10%) used externally in the form of compresses and lotions in the treatment of purulent wounds. The use of such compresses promotes, by the law of osmosis, the separation of pus from wounds and plasmolysis of bacteria (antimicrobial effect). A 2-5% NaCI solution is prescribed orally for gastric lavage in case of AgNO 3 poisoning, which is converted into slightly soluble and non-toxic silver chloride:

Ag + + CI - = AgCI (t)

Drinking soda(sodium bicarbonate, bicarbonate of soda) NaHCO 3 is used for various diseases accompanied by increased acidity - acidosis (diabetes, etc.). The mechanism for reducing acidity is the interaction of NaHCO 3 with acidic products. In this case, sodium salts of organic acids are formed, which are largely excreted in the urine, and carbon dioxide, which leaves the body with exhaled air:

NaHCO3 (p) + RCOOH (p) → RCOONa(p) + H 2 O(l) + CO 2 (g)

NaHCO 3 is also used for increased acidity of gastric juice, gastric ulcer and duodenum. When taking NaHCO 3, a neutralization reaction of excess hydrochloric acid occurs:

NaHCO 3 (s) + HCl (s) = NaCl (s) + H 2 O (l) + CO 2 (g)

It should be borne in mind that the use of baking soda should be careful, because... may cause a number of side effects.

Solutions of baking soda are used as rinses, washes for inflammatory diseases of the eyes, mucous membranes of the upper respiratory tract. The action of NaHCO 3 as an antiseptic is based on the fact that, as a result of hydrolysis, an aqueous soda solution exhibits slightly alkaline properties:

NaHCO 3 + H 2 O ↔ NaOH + H 2 CO 3

When microbial cells are exposed to alkalis, precipitation of cellular proteins occurs and, as a result, the death of microorganisms.

Glauber's salt(sodium sulfate) Na 2 SO 4 ∙10H 2 O is used as a laxative. This salt is slowly absorbed from the intestine, which leads to the maintenance of increased osmotic pressure in the intestinal cavity for a long time. As a result of osmosis, water accumulates in the intestines, its contents become liquefied, intestinal contractions intensify, and feces are eliminated faster.

Borax(sodium tetraborate) Na 2 B 4 O 7 ∙10H 2 O is used externally as an antiseptic for rinsing, douching, and lubricating. the antiseptic effect of borax is similar to the effect of baking soda and is associated with an alkaline reaction of the environment aqueous solution this salt, as well as with the formation of boric acid:

Na 2 B 4 O 7 + 7H 2 O ↔ 4H 3 BO 3 + 2NaOH

Sodium hydroxide in the form of a 10% NaOH solution, it is included in the composition of silane, used in orthopedic practice for casting fire-resistant models in the manufacture of solid prostheses from a cobalt-chrome alloy.

Radioactive isotope 24 Na is used as a tracer to determine the speed of blood flow, and it is also used to treat some forms of leukemia.

Potassium. The potassium content in the human body weighing 70 kg is approximately 160 g (4090 mmol). Potassium is the main intracellular cation, accounting for 2/3 of total number active cellular cations. In most cases, potassium is an antagonist to sodium.

Of the total amount of potassium contained in the body, 98% is found inside cells and only about 2% is in extracellular fluid. Potassium is distributed throughout the body. Its topography: liver, kidneys, heart, bone tissue, muscles, blood, brain, etc.

Potassium ions K+ play an important role in physiological processes:

muscle contraction

in the normal functioning of the heart

participates in the transmission of nerve impulses

in exchange reactions

activates the work of a number of enzymes located inside the cell

regulates acid-base balance

It has protective properties against the unwanted effects of excess sodium and normalizes blood pressure. In the body of people who eat a lot of potassium-rich vegetables - vegetarians - the amount of potassium and sodium are in balance. These people most often have lower blood pressure than their meat-loving fellow citizens.

Has an antisclerotic effect

Potassium has the ability to enhance urine formation

An adult usually consumes 2–3 g of potassium per day with food. The concentration of potassium ions in the extracellular fluid, including plasma, is normally 3.5 - 5.5 mmol/l, and the concentration of intracellular potassium is 115 - 125 mmol/l.

Rubidium and cesium. In terms of content in the human body, rubidium and cesium are classified as microelements. They are constantly contained in the body, but their biological role has not yet been clarified.

Rubidium and cesium are found in all studied organs of mammals and humans. Entering the body with food, they are quickly absorbed from the gastrointestinal tract into the blood. The average level of rubidium in the blood is 2.3-2.7 mg/l, and its concentration in erythrocytes is almost three times higher than in plasma. Rubidium and cesium are distributed very evenly in organs and tissues, and rubidium mainly accumulates in the muscles, and cesium enters the intestine and is reabsorbed in its descending sections.

The role of rubidium and cesium in some physiological processes is known. Currently, the stimulating effect of these elements on circulatory functions and the effectiveness of the use of their salts for hypotension have been established. of various origins. In the laboratory of I.P. Pavlov, S.S. Botkin found that cesium and rubidium chlorides cause an increase blood pressure for a long time and that this effect is associated mainly with increased cardiovascular activity and constriction of peripheral vessels.

Being a complete analogue of potassium, rubidium also accumulates in intracellular fluid and can replace an equivalent amount of potassium in various processes. Synergism (chemical) is the simultaneous combined effect of two (or more) factors, characterized by the fact that such a combined effect significantly exceeds the effect of each individual component. A potassium synergist, rubidium activates many of the same enzymes as potassium.

Radioactive isotopes 137 Cs and 87 Rb are used in radiotherapy of malignant tumors, as well as in the study of potassium metabolism. Due to their rapid breakdown, they can even be introduced into the body without fear of long-term harmful effects.

Franc. It is a radioactive chemical element obtained artificially. There is evidence that francium is capable of selectively accumulating in tumors at the earliest stages of their development. These observations may be useful in diagnosing cancer.

Thus, Of the IA group elements, Li, Rb, Cs are physiologically active, and Na and K are vital. The similarity of the physicochemical properties of Li and Na, due to the similarity of the electronic structure of their atoms, is also manifested in the biological action of cations (accumulation in extracellular fluid, interchangeability). A similar nature of the biological action of element cations long periods– K + , Rb + , Cs + (accumulation in intracellular fluid, interchangeability) is also due to the similarity of their electronic structure and physicochemical properties. This is the basis for the use of sodium and potassium preparations for poisoning with lithium and rubidium salts.

3. Routes of entry of alkali metals

into the human body

The ways in which chemical elements enter the human body are varied; they are presented in the diagram:

Human

In the process of evolution from inorganic to bioorganic substances, the basis for the use of certain chemical elements in the creation of biological systems is natural selection.

The table shows data on the content of group I A elements - alkali metals - in the earth's crust, sea water, plant and animal organisms and in the human body ( mass fraction V %).

The table shows that the greater the abundance of an element in the earth’s crust, the more it is in the human body.

Li

Na

K

Rb

Cs

Earth's crust

6,5∙10 -3

0,03

accurate data

No

Soil

3∙10 -3

0,63

1,36

5∙10 -3

sea ​​water

1,5∙10 -5

1,06

0,038

2∙10 -5

Plants

1∙10 -5

0,02

5∙10 -4

Animals

10 -4

0,27

10 -5

Human

10 -4

0,08

0,23

10 -5

10 -4

The alkali metals most necessary for the human body are sodium and potassium. Almost all elements enter the human body mainly through food.

Lithium sources.

Lithium is found in some mineral waters, as well as sea and rock salt. It is also found in plants, but its concentration, like any microelements, depends not only on the type and part of the plant, but also on the time of year and even day, on collection conditions and weather, as well as on the area where this plant grows.

In our country, lithium was studied by employees of the Institute of Geochemistry named after Acad. V.I. Vernadsky in Moscow. It was found that the above-ground parts of plants are richer in lithium than the roots. Most lithium is found in plants of the rose family, cloves, and nightshades, which include tomatoes and potatoes. Although within one family the difference in its content can be enormous - several dozen times. It depends on geographical location and lithium content in soil.

Sources of sodium.

Sodium is present in various food additives in the form of monosodium glutamate (flavor), sodium saccharin (sweetener), sodium nitrate (preservative), sodium ascorbate (antioxidant) and sodium bicarbonate (baking soda) as well as in some medicines(antacids). However, most of the sodium in the diet comes from salt.
NaCl levels are relatively low in all food products, which have not been subjected to special treatment. However, salt has been used as a preservative and flavoring for several centuries. It is also used as a dye, filler and to control the fermentation process (for example, when baking bread). For this reason, it is added to foods such as ham, sausages, bacon and other meat products, smoked fish and meats, canned vegetables, most butters, margarine, cheese, unsweetened foods, snack foods, and the cereals we eat at home. breakfast.

The recommended sodium intake is 1.5 grams per day. Excess salt in the diet is associated with an increased likelihood of stomach cancer and is harmful to the kidneys, especially if they have any problems with the urinary system. Excess salt is one of the leading lifestyle factors that leads to hypertension. If hypertension is asymptomatic, it increases the risk of cardiovascular disease and stroke. Current guidelines for the prevention of hypertension have shown that the most effective diet for the prevention and treatment of high blood pressure should be low in sodium and fat and include large amounts of low-fat dairy products (a source of calcium) and fruits and vegetables (a source of potassium). Thus, it is important to change the diet as a whole, rather than focusing on any one component of the diet. Other important positive factors include physical activity, normal body weight.
People with kidney disease and very young children cannot tolerate large amounts of sodium because their kidneys cannot eliminate it. For this reason, you should not add salt to the food of young children.

By law, food labels must list sodium content, but some manufacturers ignore this rule and list the amount of salt.

We remember: “ Table salt can be annoying our health!»

Sources of potassium.

The best source of potassium is plant foods. These are watermelons, melons, oranges, tangerines, bananas, dried fruits (figs, apricots, rose hips). Berries rich in potassium include lingonberries, strawberries, black and red currants. There is also a lot of potassium in vegetables (especially potatoes), legumes, wholemeal products, and rice.

The body's reaction to potassium deficiency.

With a lack of potassium in the body, muscle weakness, intestinal lethargy, and cardiac dysfunction are observed.

“I haven’t gotten up yet, I’m already tired” - this is how the doctor figuratively and clearly characterizes potassium deficiency in the body. A low potassium content in the body usually leads to asthenia (mental and physical exhaustion, fatigue), impaired renal function and depletion of the adrenal cortex. There is a risk of disruption of metabolic processes and conductivity in the myocardium.

Potassium deficiency reduces performance, slows down wound healing, and leads to impaired neuromuscular conduction. Dry skin, dullness and weakness of hair are noted (this is a matter of serious concern, especially for women and girls).

Sudden death may occur with increasing stress. There is poor transmission of nerve impulses. Diuretics (diuretics) reduce potassium absorption. When preparing food, it is necessary to pay attention to the fact that potassium compounds are water-soluble. This circumstance requires you to wash products containing it before chopping them and cook them in a small amount of water.

By the way, traditional medicine believes that craving Drinking alcohol is associated with a lack of potassium in the body.

For potassium depletion use potassium chloride KCl 4 - 5 times a day, 1 g.

The body's reaction to excess potassium.

With an excess of potassium in the body, the main functions of the heart are inhibited: a decrease in the excitability of the heart muscle, a slowdown in the heart rate, deterioration of conductivity, and a weakening of the force of heart contractions. In high concentrations, potassium ions cause cardiac arrest in diastole (the contraction phase of the ventricles of the heart). The toxic dose of potassium is 6 g. The lethal dose is 14 g. Potassium salts can be toxic to the body due to the anion associated with the potassium ion, for example, KCN (potassium cyanide).

To regulate the content of these nutrients, you can take into account the data presented in the following table.

4. Practical part

Experience 1.Flame coloring with compounds.

One of the methods for qualitative detection of alkali metal compounds is based on their ability to color the burner flame.

Solutions of alkali metal salts must be poured into test tubes. Wash the iron wire in hydrochloric acid and then ignite it in a burner flame.

Then you need to moisten the wire with a solution of the salt being tested and add it to the flame.

Salts containing lithium cations, as well as lithium color the flames red color, sodium cations and metal sodium- V yellow, potassium cations and metal potassium color the flames violet color. For better observation, you can view the color through blue glass.

Thus, Li +, Na + and K + ions were discovered in solutions of salts LiCl, NaCl, Na 2 CO 3, Na 2 SO 4, NaNO 3, KCl, KNO 3, K 2 CO 3.

Experience 2.Interaction of alkali metals with water.

Add a piece of metal, thoroughly cleaned of the oxide film, into a glass of water. After dissolving the metal, the solution medium was examined using phenolphthalein.

Carry out this experiment with pieces of lithium, sodium and potassium. The reaction with potassium was most active; it was accompanied by the combustion of potassium, violet sparks and gas evolution were observed. Sodium reacted with water, producing yellow sparks, and lithium reacted most calmly.

The resulting solutions with phenolphthalein turned crimson, indicating the presence of alkali in the solution.

2Li + 2H 2 O = 2LiOH + H 2

2Na + 2H 2 O = 2NaOH + H 2

2K + 2H 2 O = 2KOH + H 2

Experience 3. Hydrolysis of sodium and potassium salts.

The nature of the environment of salt solutions is studied using acid-base indicators.

Universal indicator papers dipped into solutions of alkali metal salts formed weak acids Na 2 CO 3 and K 2 CO 3 turned blue, which indicates alkaline reaction solutions. hydrolysis occurred in solutions - the interaction of salts with water molecules:

Na 2 CO 3 ↔ 2Na + + CO 3 2-

CO 3 2- + H 2 O ↔ HCO 3 - + OH -

Na 2 CO 3 + H 2 O ↔ NaHCO 3 + NaOH

Solutions of salts of strong acids NaNO 3, KNO 3, NaCl, KCl, LiCl showed a neutral environment (the color of the indicator paper did not change), which means that hydrolysis of these salts does not occur

Conclusions

Why is it so important to know the content of chemical elements in the body?

Chemical elements are not synthesized, unlike many organic substances, in the body, but come from outside with food, air, through the skin and mucous membranes. Therefore, the determination of chemical elements allows you to find out about:

how much does your body correspond to the ideal (by the way, about 20% of people do not have any deviations and, thus, live in harmony with nature);

Are you eating right, does your diet provide the necessary set of nutrients;

Do bad habits harm the body?

how safe is the environment in which you live; the food you eat; Your workplace;

do your stomach, intestines, liver, kidneys, skin function well, regulating the processes of absorption and excretion of nutrients;

don't you have chronic diseases or predisposition to them;

Are you being treated correctly?

What diseases are most closely related to elemental imbalance?

First of all, this is:

decreased immunity;

diseases of the skin, hair, nails;

scoliosis, osteoporosis, osteochondrosis;

hypertension;

allergies, including bronchial asthma;

diabetes, obesity;

diseases of the cardiovascular system;

blood diseases (anemia);

intestinal dysbiosis, chronic gastritis, colitis;

infertility, decreased potency in men;

impaired growth and development in children.

Many years of experience of doctors shows that more than 80% of the population have a more or less pronounced imbalance of microelements. Therefore, if you have any , you should pay attention to this!

Many scientists believe that not only are all chemical elements present in a living organism, but each of them performs a specific biological function.

We have clarified the biological role of only one group of chemical elements. Alkali metals are extremely important for human health, like most others. It is very important for human health to maintain the optimal concentration of each element: both a deficiency of an element and its excess are harmful.

Stability chemical composition the body is one of the most important and mandatory conditions for its normal functioning .

There is an erroneous, although widespread, opinion about the possibility of correcting an imbalance in the elemental composition of the human body by enriching the diet with certain products containing the necessary mineral elements. However, it should be taken into account that the presence of necessary macro- and microelements in food and water (which is especially obvious for residents of rural areas) depends to a large extent on the so-called “local biogeochemical cycle"elements, which determines the content of macro- and microelements in food plants and animals.

A deficiency or excess of certain elements in the human body, as a rule, is a consequence of a deficiency or excess of these elements passing through the food chain: from soil to plants and animals to humans. When a deficiency of any element develops, nutritional correction is not enough, even if products from other regions are used for this purpose, the soils of which are enriched with the necessary microelement.

Only an individual selection of special mineral and other preparations aimed at normalizing the microelement balance of the body will provide real and effective help in the development of a pathological condition.

In conclusion, we present the commandments of the people and scientific medicine that everyone needs to know:

Everything is connected to everything.

Everything has to go somewhere.

Nature knows best.

Nothing comes for free.

Literature used

1. Gabrielyan O.S. Chemistry, 9th grade, Textbook for educational institutions. - M. “Bustard”, 2001

2. Glinka N.L. General chemistry, Textbook for universities. - L. “Chemistry”, 1983

3. General chemistry. Chemistry of biogenic elements. Textbook for honey. specialist. call. Yu.A. Ershov and others - M. " graduate School", 1993

4. Sychev A.P., Fadeev G.N. Chemistry of metals. Study guide. – M. “Enlightenment”, 1984

5. MHTML. Do c ument. integrated lesson “Alkali metals”. Festival "Open Lesson", 2003

6.

7.

From the entire periodic table most elements represents a group of metals. amphoteric, transitional, radioactive - there are a lot of them. All metals play a huge role not only in nature and human biological life, but also in various industries. It’s not for nothing that the 20th century was called “iron”.

Metals: general characteristics

All metals share common chemical and physical properties, by which they are easily distinguished from non-metallic substances. So, for example, the building crystal lattice allows them to be:

• conductors of electric current;
• good thermal conductors;
• malleable and ductile;
• durable and shiny.

Of course, there are differences among them. Some metals shine silver color, others - more matte white, others - generally red and yellow. There are also differences in thermal and electrical conductivity. However, these parameters are still common to all metals, while non-metals have more differences than similarities.

By chemical nature, all metals are reducing agents. Depending on the reaction conditions and specific substances, they can also act as oxidizing agents, but rarely. Capable of forming numerous substances. Chemical compounds metals are found in nature in huge quantities as part of ores or minerals, minerals and other rocks. The degree is always positive and can be constant (aluminum, sodium, calcium) or variable (chromium, iron, copper, manganese).

Many of them are widely used as building materials and are used in the most different industries science and technology.

Chemical compounds of metals

Among these, several main classes of substances should be mentioned, which are products of the interaction of metals with other elements and substances.

1. Oxides, hydrides, nitrides, silicides, phosphides, ozonides, carbides, sulfides and others - binary compounds with non-metals, most often belong to the class of salts (except oxides).
2. Hydroxides - general formula Me + x (OH) x.
3. Salt. Metal compounds with acidic residues. May be different:

• average;
• sour;
• double;
• basic;
• complex.

4. Compounds of metals with organic substances - organometallic structures.

5. Compounds of metals with each other - alloys, which are obtained in different ways.

Metal joining options

Substances that can contain two substances at the same time different metals and more, are divided into:

• alloys;
• double salts;
• complex compounds;
• intermetallic compounds.

Methods for joining metals together also vary. For example, to produce alloys, the method of melting, mixing and solidifying the resulting product is used.

Intermetallic compounds are formed as a result of direct chemical reactions between metals, often explosive (for example, zinc and nickel). Such processes require special conditions: very high temperature, pressure, vacuum, lack of oxygen, and others.

Soda, salt, caustic soda - all these are compounds of alkali metals in nature. They exist in pure form, forming deposits, or are part of the combustion products of certain substances. Sometimes they are obtained in a laboratory method. But these substances are always important and valuable, since they surround a person and shape his life.

Alkali metal compounds and their uses are not limited to sodium. Salts such as:

• potassium chloride;
• (potassium nitrate);
• potassium carbonate;
• sulfate.

They are all valuable mineral fertilizers, used in agriculture.

Alkaline earth metals - compounds and their applications

This category includes elements of the second group of the main subgroup of the system of chemical elements. Their constant degree oxidation +2. These are active reducing agents that easily enter into chemical reactions with most compounds and simple substances. They show everything typical properties metals: luster, ductility, heat and electrical conductivity.

The most important and common of these are magnesium and calcium. Beryllium is amphoteric, barium and radium are rare elements. All of them are capable of forming following types connections:

• intermetallic;
• oxides;
• hydrides;
• binary salts (compounds with non-metals);
• hydroxides;
• salts (double, complex, acidic, basic, medium).

Let's consider the most important connections from a practical point of view and their scope.

Magnesium and calcium salts

Alkaline earth metal compounds such as salts have important for living organisms. After all, calcium salts are the source of this element in the body. And without it, the normal formation of the skeleton, teeth, horns in animals, hooves, hair and coat, and so on is impossible.

Thus, the most common salt of the alkaline earth metal calcium is carbonate. Its other names:

• marble;
• limestone;
• dolomite.

It is used not only as a supplier of calcium ions to a living organism, but also as a building material, raw material for chemical production, in the cosmetics industry, glass industry, and so on.

Alkaline earth metal compounds such as sulfates are also important. For example, barium sulfate (medical name "barite porridge") is used in x-ray diagnostics. Calcium sulfate in the form of crystalline hydrate is gypsum, which is found in nature. It is used in medicine, construction, and stamping casts.

Alkaline earth metal phosphorus

These substances have been known since the Middle Ages. Previously, they were called phosphors. This name still appears today. By their nature, these compounds are sulfides of magnesium, strontium, barium, and calcium.

With certain processing, they are capable of exhibiting phosphorescent properties, and the glow is very beautiful, from red to bright purple. This is used in the manufacture of road signs, workwear and other things.

Complex connections

Substances that include two or more different elements metallic nature - complex metal compounds. Most often they are liquids with beautiful and colorful colors. Used in analytical chemistry for qualitative determination of ions.

Such substances are capable of forming not only alkali and alkaline earth metals, but also all others. There are hydroxo complexes, aqua complexes and others.