Alkali metals can interact with non-metals. Non-metals - preparation for the exam in chemistry. Examples of problem solving

These are elements of group I periodic system: lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr); very soft, plastic, low-melting and light, usually silvery-white; chemically very active; react violently with water, forming alkalis (where the name comes from).

All alkali metals are extremely active, in all chemical reactions they exhibit reducing properties, give up their only valence electron, turning into a positively charged cation, and exhibit the only oxidation state +1.

The regenerative capacity increases in the order –– Li – Na – K – Rb – Cs.

All alkali metal compounds are ionic.

Almost all salts are water soluble.

Low melting points,

Low density values,

Soft, cut with a knife

Due to their activity, alkali metals are stored under a layer of kerosene to block the access of air and moisture. Lithium is very light and floats to the surface in kerosene, so it is stored under a layer of petroleum jelly.

Chemical properties of alkali metals

1. Alkali metals actively interact with water:

2Na + 2H 2 O → 2NaOH + H 2

2Li + 2H 2 O → 2LiOH + H 2

2. Reaction of alkali metals with oxygen:

4Li + O 2 → 2Li 2 O (lithium oxide)

2Na + O 2 → Na 2 O 2 (sodium peroxide)

K + O 2 → KO 2 (potassium superoxide)

In air, alkali metals are instantly oxidized. Therefore, they are stored under a layer of organic solvents (kerosene, etc.).

3. In the reactions of alkali metals with other non-metals, binary compounds are formed:

2Li + Cl 2 → 2LiCl (halides)

2Na + S → Na 2 S (sulfides)

2Na + H 2 → 2NaH (hydrides)

6Li + N 2 → 2Li 3 N (nitrides)

2Li + 2C → Li 2 C 2 (carbides)

4. Reaction of alkali metals with acids

(carried out rarely, there is a competing reaction with water):

2Na + 2HCl → 2NaCl + H 2

5. Interaction of alkali metals with ammonia

(sodium amide is formed):

2Li + 2NH 3 \u003d 2LiNH 2 + H 2

6. Interaction of alkali metals with alcohols and phenols, which in this case exhibit acidic properties:

2Na + 2C 2 H 5 OH \u003d 2C 2 H 5 ONa + H 2;

2K + 2C 6 H 5 OH \u003d 2C 6 H 5 OK + H 2;

7. Qualitative reaction for alkali metal cations - coloring the flame in the following colors:

Li + - carmine red

Na + - yellow

K +, Rb + and Cs + - purple

Getting alkali metals

Metallic lithium, sodium and potassium get electrolysis of molten salts (chlorides), and rubidium and cesium - by reduction in vacuum when their chlorides are heated with calcium: 2CsCl + Ca \u003d 2Cs + CaCl 2
Vacuum-thermal production of sodium and potassium is also used on a small scale:

2NaCl + CaC 2 \u003d 2Na + CaCl 2 + 2C;
4KCl + 4CaO + Si \u003d 4K + 2CaCl 2 + Ca 2 SiO 4.

Active alkali metals are released in vacuum-thermal processes due to their high volatility (their vapors are removed from the reaction zone).

Features of the chemical properties of group I s-elements and their physiological action

The electronic configuration of the lithium atom is 1s 2 2s 1. It has the largest atomic radius in the 2nd period, which facilitates the detachment of a valence electron and the appearance of a Li + ion with a stable configuration of an inert gas (helium). Consequently, its compounds are formed with the transfer of an electron from lithium to another atom and the formation of an ionic bond with a small fraction of covalence. Lithium is a typical metallic element. As a substance, it is an alkali metal. It differs from other members of group I by its small size and the lowest, in comparison with them, activity. In this respect, it resembles the Group II element, magnesium, located diagonally from Li. In solutions, the Li + ion is highly solvated; it is surrounded by several tens of water molecules. Lithium in terms of the energy of solvation - the addition of solvent molecules, is closer to the proton than to the cations of alkali metals.

The small size of the Li + ion, the high charge of the nucleus and only two electrons create conditions for the appearance of a rather significant field of a positive charge around this particle, therefore, in solutions, a significant number of molecules of polar solvents are attracted to it and its coordination number is large, the metal is capable of forming a significant number of organolithium compounds ...

The third period begins with sodium, therefore, at the external level, only 1e - , occupying a 3s orbital. The radius of the Na atom is the largest in the 3rd period. These two features determine the nature of the element. Its electronic configuration is 1s 2 2s 2 2p 6 3s 1 . The only oxidation state of sodium is +1. Its electronegativity is very small, therefore, sodium is present in compounds only in the form of a positively charged ion and gives chemical bond ionic character. The Na + ion is much larger in size than Li +, and its solvation is not so great. However, it does not exist in free form in solution.

The physiological significance of the K + and Na + ions is associated with their different adsorbability on the surface of the components that make up the earth's crust. Sodium compounds are only slightly subject to adsorption, while potassium compounds are firmly held by clay and other substances. Cell membranes, being the cell - medium interface, are permeable to K + ions, as a result of which the intracellular concentration of K + is much higher than that of Na + ions. At the same time, the concentration of Na + in blood plasma exceeds the content of potassium in it. This circumstance is associated with the occurrence membrane potential cells. Ions K + and Na + are one of the main components of the liquid phase of the body. Their ratio with Ca 2+ ions is strictly defined, and its violation leads to pathology. The introduction of Na + ions into the body does not have a noticeable harmful effect. An increase in the content of K + ions is harmful, but under normal conditions, an increase in its concentration never reaches dangerous values. The influence of Rb +, Cs +, Li + ions has not yet been sufficiently studied.

Of various defeatsassociated with the use of alkali metal compounds, burns with hydroxide solutions are most common. The action of alkalis is associated with the dissolution of skin proteins in them and the formation of alkaline albuminates. Alkali is released again as a result of their hydrolysis and acts on the deeper layers of the body, causing ulcers. Under the influence of alkalis, nails become dull and brittle. Damage to the eyes, even with very dilute alkaline solutions, is accompanied not only by superficial damage, but by disturbances in the deeper parts of the eye (iris) and leads to blindness. During the hydrolysis of alkali metal amides, alkali and ammonia are simultaneously formed, causing fibrinous type tracheobronchitis and pneumonia.

Potassium was obtained by G. Davy almost simultaneously with sodium in 1807 by electrolysis of wet potassium hydroxide. From the name of this compound - "caustic potassium" and the element got its name. The properties of potassium differ markedly from those of sodium, which is due to the difference in the radii of their atoms and ions. In potassium compounds, the bond is more ionic, and in the form of the K + ion, it has a lower polarizing effect than sodium, due to its large size. The natural mixture consists of three isotopes 39 K, 40 K, 41 K. One of them is 40 K ‑ radioactive and a certain proportion of the radioactivity of minerals and soil is associated with the presence of this isotope. Its half-life is long - 1.32 billion years. It is quite easy to determine the presence of potassium in a sample: metal vapors and its compounds color the flame in a violet-red color. The spectrum of the element is quite simple and proves the presence of 1e - in the 4s orbital. Its study served as one of the grounds for finding general patterns in the structure of the spectra.

In 1861, while studying the salt of mineral springs by spectral analysis, Robert Bunsen discovered a new element. Its presence was proved by dark red lines in the spectrum, which were not given by other elements. According to the color of these lines, the element was named rubidium (rubidus-dark red). In 1863 R. Bunsen obtained this metal in its pure form by reduction of rubidium tartrate (tartrate salt) with soot. A feature of the element is the easy excitability of its atoms. Its electron emission appears under the influence of red rays of the visible spectrum. This is due to the small difference in the energies of the atomic 4d and 5s orbitals. Of all alkaline elements with stable isotopes, rubidium (like cesium) has one of the largest atomic radii and a small ionization potential. These parameters determine the nature of the element: high electropositiveness, extreme chemical activity, low melting point (39 0 C) and low resistance to external influences.

The discovery of cesium, like rubidium, is associated with spectral analysis. In 1860 R. Bunsen discovered two bright blue lines in the spectrum that did not belong to any element known by that time. Hence the name "cesius" (caesius), which means sky blue. It is the last element of the alkali metal subgroup that still occurs in measurable amounts. The largest atomic radius and the smallest first ionization potentials determine the character and behavior of this element. It has a pronounced electropositiveness and pronounced metallic qualities. The desire to donate the outer 6s electron leads to the fact that all its reactions proceed extremely violently. The small difference in the energies of the atomic 5d and 6s orbitals is responsible for the slight excitability of atoms. Electronic emission from cesium is observed under the influence of invisible infrared rays (heat). This feature of the atomic structure determines the good electrical conductivity of the current. All this makes cesium irreplaceable in electronic devices... Recently, more and more attention has been paid to cesium plasma as the fuel of the future and in connection with the solution of the problem of thermonuclear fusion.

In air, lithium actively reacts not only with oxygen, but also with nitrogen and is covered with a film consisting of Li 3 N (up to 75%) and Li 2 O. The rest of the alkali metals form peroxides (Na 2 O 2) and superoxides (K 2 O 4 or KO 2).

The listed substances react with water:

Li 3 N + 3 H 2 O \u003d 3 LiOH + NH 3;

Na 2 O 2 + 2 H 2 O \u003d 2 NaOH + H 2 O 2;

K 2 O 4 + 2 H 2 O \u003d 2 KOH + H 2 O 2 + O 2.

For air regeneration in submarines and spaceships, in the isolating gas masks and breathing apparatus of combat swimmers (underwater saboteurs), a mixture of "oxon" was used:

Na 2 O 2 + CO 2 \u003d Na 2 CO 3 + 0.5O 2;

K 2 O 4 + CO 2 \u003d K 2 CO 3 + 1.5 O 2.

It is currently the standard filling of regenerating cartridges for insulating gas masks for firefighters.
Alkali metals react with hydrogen when heated to form hydrides:

Lithium hydride is used as a strong reducing agent.

Hydroxides alkali metals corrode glass and porcelain dishes, they cannot be heated in quartz dishes:

SiO 2 + 2NaOH \u003d Na 2 SiO 3 + H 2 O.

Sodium and potassium hydroxides do not split off water when heated up to their boiling points (more than 1300 0 С). Some sodium compounds are called sodas:

a) soda ash, anhydrous soda, laundry soda or just soda - sodium carbonate Na 2 CO 3;
b) crystalline soda - sodium carbonate crystalline hydrate Na 2 CO 3. 10H 2 O;
c) bicarbonate or drinking - sodium bicarbonate NaHCO 3;
d) sodium hydroxide NaOH is called caustic soda or caustic.

Salt19 Salt

1. Metal + Non-metal.Inert gases do not enter into this interaction. The higher the electronegativity of a non-metal, the more a large number metals it will react. For example, fluorine reacts with all metals, and hydrogen only with active ones. The more to the left in the row of metal activity the metal is, the more it can react with non-metals. For example, gold reacts only with fluorine, lithium - with all non-metals.

2. Non-metal + non-metal.In this case, a more electronegative non-metal acts as an oxidizing agent, less EO as a reducing agent. Non-metals with close electronegativity interact poorly with each other, for example, the interaction of phosphorus with hydrogen and silicon with hydrogen is practically impossible, since the equilibrium of these reactions is shifted towards the formation simple substances... Helium, neon and argon do not react with non-metals, other inert gases in harsh conditions can react with fluorine. Oxygen does not interact with chlorine, bromine and iodine. Oxygen can react with fluorine at low temperatures.

3. Metal + acidic oxide.Metal reduces non-metal from oxide. Thereafter, the excess metal can react with the resulting non-metal. For instance:

2Mg + SiO 2 \u003d 2MgO + Si (with a lack of magnesium)

2Mg + SiO 2 \u003d 2MgO + Mg 2 Si (with an excess of magnesium)

4. Metal + acid.Metals in the series of voltages to the left of hydrogen react with acids with the release of hydrogen.

The exception is acids - oxidizing agents (concentrated sulfuric and any nitric acid), which can react with metals standing in a series of voltages to the right of hydrogen, hydrogen is not released in the reactions, but water and an acid reduction product are obtained.

It should be noted that when a metal interacts with an excess of a polybasic acid, an acid salt can be obtained: Mg + 2H 3 PO 4 \u003d Mg (H 2 PO 4) 2 + H 2.

If the product of the interaction of acid and metal is an insoluble salt, then the metal is passivated, since the surface of the metal is protected by the insoluble salt from the action of the acid. For example, the effect of dilute sulfuric acid on lead, barium or calcium.

5. Metal + salt. In solutionthis reaction involves a metal standing in the series of voltages to the right of magnesium, including magnesium itself, but to the left of the metal of the salt. If the metal is more active than magnesium, then it reacts not with salt, but with water to form alkali, which subsequently reacts with salt. In this case, the original salt and the resulting salt must be soluble. The insoluble product passivates the metal.

However, there are exceptions to this rule:

2FeCl 3 + Cu \u003d CuCl 2 + 2FeCl 2;

2FeCl 3 + Fe \u003d 3FeCl 2. Since iron has an intermediate oxidation state, its salt in the highest oxidation state is easily reduced to a salt in an intermediate oxidation state, oxidizing even less active metals.

In melts a number of metal stresses do not work. It is possible to determine whether a reaction between a salt and a metal is possible only with the help of thermodynamic calculations. For example, sodium can displace potassium from the potassium chloride melt, since potassium is more volatile: Na + KCl \u003d NaCl + K (this reaction is determined by the entropy factor). On the other hand, aluminum was obtained by displacement from sodium chloride: 3Na + AlCl 3 \u003d 3NaCl + Al. This process is exothermic, it is determined by the enthalpy factor.

It is possible that the salt decomposes when heated, and its decomposition products can react with metal, for example, aluminum nitrate and iron. Aluminum nitrate decomposes when heated to aluminum oxide, nitric oxide (IV) and oxygen, oxygen and nitrogen oxide will oxidize iron:

10Fe + 2Al (NO 3) 3 \u003d 5Fe 2 O 3 + Al 2 O 3 + 3N 2

6. Metal + basic oxide.Just as in molten salts, the possibility of these reactions is determined thermodynamically. Aluminum, magnesium and sodium are often used as reducing agents. For example: 8Al + 3Fe 3 O 4 \u003d 4Al 2 O 3 + 9Fe exothermic reaction, enthalpy factor); 2 Al + 3Rb 2 O \u003d 6Rb + Al 2 O 3 (volatile rubidium, enthalpy factor).

7. Non-metal + basic oxide.Two options are possible here: 1) non-metal - reducing agent (hydrogen, carbon): CuO + H 2 \u003d Cu + H 2 O; 2) non-metal - oxidizing agent (oxygen, ozone, halogens): 4FeO + O 2 \u003d 2Fe 2 O 3.

8. Non-metal + base.As a rule, the reaction takes place between a non-metal and an alkali. Not all non-metals can react with alkalis: it must be remembered that halogens (differently depending on temperature), sulfur (when heated), silicon, phosphorus enter into this interaction.

2KOH + Cl 2 \u003d KClO + KCl + H 2 O (in the cold)

6KOH + 3Cl 2 \u003d KClO 3 + 5KCl + 3H 2 O (in hot solution)

6KOH + 3S \u003d K 2 SO 3 + 2K 2 S + 3H 2 O

2KOH + Si + H 2 O \u003d K 2 SiO 3 + 2H 2

3KOH + 4P + 3H 2 O \u003d PH 3 + 3KPH 2 O 2

9. Non-metal + acidic oxide.Two options are also possible here:

1) non-metal - reducing agent (hydrogen, carbon):

CO 2 + C \u003d 2CO;

2NO 2 + 4H 2 \u003d 4H 2 O + N 2;

SiO 2 + C \u003d CO 2 + Si. If the resulting non-metal can react with the metal used as a reducing agent, then the reaction will go further (with an excess of carbon) SiO 2 + 2C \u003d CO 2 + SiC

2) non-metal - oxidizing agent (oxygen, ozone, halogens):

2CO + O 2 \u003d 2CO 2.

CO + Cl 2 \u003d COCl 2.

2NO + O 2 \u003d 2NO 2.

10. Acidic oxide + basic oxide... The reaction takes place if the resulting salt exists in principle. For example, alumina can react with sulfuric anhydride to form aluminum sulfate, but cannot react with carbon dioxide because no corresponding salt exists.

11. Water + basic oxide... The reaction is possible if alkali is formed, that is soluble base (or slightly soluble, in the case of calcium). If the base is insoluble or slightly soluble, then the reverse reaction of decomposition of the base into oxide and water takes place.

12. Basic oxide + acid... The reaction is possible if the resulting salt exists. If the resulting salt is insoluble, the reaction can be passivated due to blocking the acid's access to the oxide surface. In the case of an excess of a polybasic acid, an acid salt may form.

13. Acid oxide + base... Typically, the reaction is between an alkali and an acidic oxide. If the acidic oxide corresponds to a polybasic acid, an acidic salt can be obtained: CO 2 + KOH \u003d KHCO 3.

Acidic oxides corresponding to strong acids can react with insoluble bases.

Sometimes oxides corresponding to weak acids react with insoluble bases, and a middle or basic salt can be obtained (as a rule, a less soluble substance is obtained): 2Mg (OH) 2 + CO 2 \u003d (MgOH) 2 CO 3 + H 2 O.

14. Acid oxide + salt.The reaction can take place in the melt and in solution. In the melt, the less volatile oxide displaces the more volatile oxide from the salt. In solution, the oxide corresponding to the stronger acid displaces the oxide corresponding to the weaker acid. For example, Na 2 CO 3 + SiO 2 \u003d Na 2 SiO 3 + CO 2, in the forward direction this reaction takes place in the melt, carbon dioxide is more volatile than silicon oxide; in the opposite direction, the reaction proceeds in solution, carbonic acid is stronger than silicic acid, besides, silicon oxide precipitates.

It is possible to combine an acid oxide with its own salt, for example, dichromate can be obtained from chromate, and disulfate from sulfate, disulfite from sulfite:

Na 2 SO 3 + SO 2 \u003d Na 2 S 2 O 5

To do this, you need to take a crystalline salt and a pure oxide, or a saturated salt solution and an excess of acidic oxide.

In solution, salts can react with their own acidic oxides to form acidic salts: Na 2 SO 3 + H 2 O + SO 2 \u003d 2NaHSO 3

15. Water + acidic oxide... The reaction is possible if a soluble or slightly soluble acid is formed. If the acid is insoluble or slightly soluble, then there is a reverse reaction of acid decomposition into oxide and water. For example, sulfuric acid is characterized by the reaction of obtaining from oxide and water, the decomposition reaction practically does not take place, silicic acid cannot be obtained from water and oxide, but it easily decomposes into these components, but carbonic and sulfurous acids can participate in both direct and back reactions.

16. Base + acid.The reaction takes place if at least one of the reacting substances is soluble. Depending on the ratio of reagents, medium, acidic and basic salts can be obtained.

17. Base + salt.The reaction takes place if both initial substances are soluble, and at least one non-electrolyte or weak electrolyte (precipitate, gas, water) is obtained as a product.

18. Salt + acid.As a rule, the reaction proceeds if both initial substances are soluble, and at least one non-electrolyte or weak electrolyte (precipitate, gas, water) is obtained as a product.

A strong acid can react with insoluble salts of weak acids (carbonates, sulfides, sulfites, nitrites), and a gaseous product is liberated.

Reactions between concentrated acids and crystalline salts are possible if a more volatile acid is obtained: for example, hydrogen chloride can be obtained by the action of concentrated sulfuric acid on crystalline sodium chloride, hydrogen bromide and hydrogen iodide - by the action of orthophosphoric acid on the corresponding salts. You can act with an acid on your own salt to obtain an acidic salt, for example: BaSO 4 + H 2 SO 4 \u003d Ba (HSO 4) 2.

19. Salt + salt.As a rule, the reaction proceeds if both initial substances are soluble, and at least one non-electrolyte or weak electrolyte is obtained as a product.

Pay special attention to those cases when salt is formed, which is shown in the solubility table with a dash. 2 options are possible here:

1) salt doesn't exist because irreversibly hydrolyzed ... These are the majority of carbonates, sulfites, sulfides, silicates of trivalent metals, as well as some salts of divalent metals and ammonium. Trivalent metal salts are hydrolyzed to the corresponding base and acid, and divalent metal salts to less soluble basic salts.

Let's consider some examples:

2FeCl 3 + 3Na 2 CO 3 \u003d Fe 2 (CO 3) 3 + 6NaCl (1)

Fe 2 (CO 3) 3 + 6H 2 O \u003d 2Fe (OH) 3 + 3 H 2 CO 3

H 2 CO 3 decomposes into water and carbon dioxide, water in the left and right parts is reduced and it turns out: Fe 2 (CO 3) 3 + 3H 2 O \u003d 2Fe (OH) 3 + 3 CO 2(2)

If we now combine (1) and (2) equations and reduce the iron carbonate, we get a summary equation reflecting the interaction of iron (III) chloride and sodium carbonate: 2FeCl 3 + 3Na 2 CO 3 + 3H 2 O \u003d 2Fe (OH) 3 + 3CO 2 + 6NaCl

CuSO 4 + Na 2 CO 3 \u003d CuCO 3 + Na 2 SO 4 (1)

The underlined salt does not exist due to irreversible hydrolysis:

2CuCO 3+ H 2 O \u003d (CuOH) 2 CO 3 + CO 2 (2)

If we now combine (1) and (2) equations and reduce copper carbonate, we get a summary equation reflecting the interaction of sulfate (II) and sodium carbonate:

2CuSO 4 + 2Na 2 CO 3 + H 2 O \u003d (CuOH) 2 CO 3 + CO 2 + 2Na 2 SO 4

2) Salt doesn't exist by intramolecular oxidation-reduction , such salts include Fe 2 S 3, FeI 3, CuI 2. As soon as they are obtained, they immediately decompose: Fe 2 S 3 \u003d 2FeS + S; 2FeI 3 \u003d 2FeI 2 + I 2; 2CuI 2 \u003d 2CuI + I 2

For instance; FeCl 3 + 3KI \u003d FeI 3 + 3KCl (1),

but instead of FeI 3 you need to write down the products of its decomposition: FeI 2 + I 2.

Then it turns out: 2FeCl 3 + 6KI \u003d 2FeI 2 + I 2 + 6KCl

This is not the only way to record this reaction, if iodide was in short supply, then iodine and iron (II) chloride can be obtained:

2FeCl 3 + 2KI \u003d 2FeCl 2 + I 2 + 2KCl

The proposed scheme does not say anything about amphoteric compounds and their corresponding simple substances. We will pay special attention to them. So, amphoteric oxide in this scheme can take the place of acid and base oxides, amphoteric hydroxide - the place of acid and base. It must be remembered that, acting as acidic, amphoteric oxides and hydroxides form ordinary salts in an anhydrous medium, and complex salts in solutions:

Al 2 O 3 + 2NaOH \u003d 2NaAlO 2 + H 2 O (fusion)

Al 2 O 3 + 2NaOH + 3H 2 O \u003d 2Na (in solution)

Simple substances corresponding to amphoteric oxides and hydroxides react with alkali solutions to form complex salts and release hydrogen: 2Al + 2NaOH + 6H 2 O \u003d 2Na + 3H 2

THE TASK

Discuss the possibility of interaction ...This means that you must decide:

1) is the reaction possible;

2) if possible, then under what conditions (in solution, in a melt, during heating, etc.), if not possible, then why;

3) whether different products can be obtained under different (what) conditions.

After that, you must write down all possible reactions.

For example: 1. Discuss the possibility of interaction of magnesium with potassium nitrate.

1) Reaction is possible

2) It can occur in the melt (when heated)

3) In the melt, the reaction is possible, since nitrate decomposes with the release of oxygen, which oxidizes magnesium.

KNO 3 + Mg \u003d KNO 2 + MgO

2. Discuss the possibility of interaction of sulfuric acid with sodium chloride.

1) Reaction is possible

2) It can happen between concentrated acid and crystal salt

3) Sodium sulfate and sodium hydrogen sulfate can be obtained as a product (in an excess of acid, when heated)

H 2 SO 4 + NaCl \u003d NaHSO 4 + HCl

H 2 SO 4 + 2NaCl \u003d Na 2 SO 4 + 2HCl

Discuss the possibility of a reaction between:

1. Phosphoric acid and potassium hydroxide;

2. Zinc oxide and sodium hydroxide;

3. Potassium sulfite and iron (III) sulfate;

4. Chloride of copper (II) and potassium iodide;

5. Calcium carbonate and aluminum oxide;

6. Carbon dioxide and sodium carbonate;

7. Iron (III) chloride and hydrogen sulfide;

8. Magnesium and sulfur dioxide;

9. Potassium dichromate and sulfuric acid;

10. Sodium and sulfur.

Let's do a little analysis of C2 examples

All elements of the IA group of the periodic table are called alkali metals (AL), i.e. lithium Li, sodium Na, potassium K, rubidium Rb, cesium Cs, francium Fr.

At the AM atoms on the external electronic level there is only one electron per s-sublevel, easily tearing off when flowing chemical reactions... In this case, a positively charged particle, a cation with a charge of +1, is formed from a neutral alkali metal atom:

M 0 - 1 e → M +1

The alkali metal family is the most active among other groups of metals; therefore, in nature, they can be found in free form, i.e. in the form of simple substances is impossible.

Simple substances alkali metals are extremely powerful reducing agents.

Interaction of alkali metals with non-metals

with oxygen

Alkali metals react with oxygen even at room temperature, and therefore must be stored under a layer of some hydrocarbon solvent, such as, for example, kerosene.

The interaction of alkali metals with oxygen leads to different products. With the formation of oxide, only lithium reacts with oxygen:

4Li + O 2 \u003d 2Li 2 O

Sodium in a similar situation forms with oxygen sodium peroxideNa 2 O 2:

2Na + O 2 \u003d Na 2 O 2,

and potassium, rubidium and cesium are mainly superoxides (superoxides), of the general formula MeO 2:

Rb + O 2 \u003d RbO 2

with halogens

Alkali metals actively react with halogens, forming alkali metal halides with an ionic structure:

2Li + Br 2 \u003d 2LiBr lithium bromide

2Na + I 2 \u003d 2NaI sodium iodide

2K + Cl 2 \u003d 2KCl potassium chloride

with nitrogen

Lithium reacts with nitrogen already at ordinary temperature, while nitrogen reacts with the rest of the alkali metals when heated. In all cases, alkali metal nitrides are formed:

6Li + N 2 \u003d 2Li 3 N lithium nitride

6K + N 2 \u003d 2K 3 N potassium nitride

with phosphorus

Alkali metals react with phosphorus when heated to form phosphides:

3Na + P \u003d Na 3 P sodium phosphide

3K + P \u003d K 3 P potassium phosphide

with hydrogen

Heating alkali metals in a hydrogen atmosphere leads to the formation of alkali metal hydrides containing hydrogen in a rare oxidation state - minus 1:

H 2 + 2K \u003d 2KH -1 potassium hydride

H 2 + 2Rb \u003d 2RbH rubidium hydride

with gray

The interaction of alkali metals with sulfur occurs upon heating with the formation of sulfides:

S + 2K \u003d K 2 S sulfide potassium

S + 2Na \u003d Na 2 S sodium sulfide

Interaction of alkali metals with complex substances

with water

All alkali metals actively react with water with the formation of gaseous hydrogen and alkali, which is why these metals received the corresponding name:

2HOH + 2Na \u003d 2NaOH + H 2

2K + 2HOH \u003d 2KOH + H 2

Lithium reacts with water quite calmly, sodium and potassium self-ignite during the reaction, and rubidium, cesium and francium react with water with a powerful explosion.

with halogenated hydrocarbons (Wurz reaction):

2Na + 2C 2 H 5 Cl → 2NaCl + C 4 H 10

2Na + 2C 6 H 5 Br → 2NaBr + C 6 H 5 –C 6 H 5

with alcohols and phenols

ChM react with alcohols and phenols, replacing hydrogen in the hydroxyl group of organic matter:

2CH 3 OH + 2K \u003d 2CH 3 OK + H 2

potassium methoxide

2C 6 H 5 OH + 2Na \u003d 2C 6 H 5 ONa + H 2

sodium phenolate

Topic No. 3. CHEMICAL PROPERTIES OF NON-METALS

Plan

1. Basic chemical properties of non-metals.

2. Oxides of non-metallic elements.

3. Distribution of non-metallic elements in nature.

4. Application of non-metals.

1. Basic chemical properties of non-metals

Non-metals (excluding inert gases) chemicallyactive substances.

In reactions with metals, atoms of non-metallic elements attach electrons, and in reactions with non-metals they form joint electron pairs.

The electronegativity series helps to find out to which atom the common electron pairs are shifted:

F, O, N, Cl, Br, I, S, C, Se, H, P, As, B, Si

electronegativity decreases

Interaction of non-metals with metals:

2Mg + O 2 \u003d 2MgO (magnesium oxide)

6Li + N 2 \u003d 2Li 3 N (lithium nitride)

2Al + 3Cl 2 \u003d 2AlCl 3 (aluminum chloride)

Ca + H 2 \u003d CaH 2 (calcium hydride)

Fe + S \u003d FeS (ferum (II) sulfide)

When non-metals interact with metals, binary compounds with ionic chemical bonds are formed.

2 ... Interaction of non-metals with oxygen:

C + O 2 \u003d CO 2 (carbon (IV) oxide)

S + O 2 \u003d SO 2 (c ulfur (IV) oxide)

The products of the interaction of non-metals with oxygen are binary compounds with a covalent polar bond -oxides in which oxygen has an oxidation state- 2.

3. Interaction of non-metals with hydrogen:

H 2 + Cl 2 \u003d 2HCl (hydrogen chloride or hydrogen chloride)

H 2 + S \u003d H 2 S (hydrogen sulfide or hydrogen sulfide)

When non-metals interact with hydrogen, volatile (gaseous or liquid) binary compounds with a covalent polar bond are formed.

4. Interaction of non-metals with other non-metals:

C + 2S \u003d CS 2 (carbon (IV) sulfide)

Si + 2Cl 2 \u003d SiCl 4 (silicon (IV) chloride)

The products of the interaction of two non-metals are substances with different state of aggregationwho have covalent type chemical bond.

Oxides of non-metallic elements

Oxides of non-metallic elements are divided into:

a) salt-forming (most of them) and

b) non-salt-forming(CO, NO, N 2 O, H 2 O).

Among the oxides there are gaseous substances (CO, CO2, SO 2 ), solids (R2 O 5), liquid (H 2 O, Cl 2 O 7).

In all oxides, without exception, the atoms of nonmetallic elements connected with Oxygen havepositive oxidation states.

Most oxides of non-metallic elementsacidic ... They interact:

with water with the formation of acids,
with basic and amphoteric oxides with the formation of salts,
with bases and amphoteric hydroxides with the formation of salts and water.

Distribution of non-metallic elements in nature

Nonmetals more common in nature than metals.

The air contains: nitrogen, oxygen, inert gases.

The deposits of native sulfur in the Carpathian region are one of the largest in the world.

An industrial deposit of graphite in Ukraine is the Zavalievskoe deposit, the raw material of which is used by the Mariupol Graphite Plant.

In the Zhytomyr region, in Volyn, rocks have been found that may contain diamonds, but industrial deposits have not yet been discovered.

Atoms of non-metallic elements form various complex substances, among which oxides and salts dominate.

Application of non-metals

Oxygen:

Breathing processes

Combustion,

Metabolism and energy,

Metal production.

Hydrogen:

Ammonia production,

Chloric acid,

Methanol,

Conversion of liquid fats to solid,

Welding and cutting of refractory metals,

Recovery of metals from ores.

Sulfur:

Getting sulfate acid,

Making rubber from rubber,

Production of matches,

Black powder

Manufacturing of medicines.

Bor:

Component of neutron-absorbing materials of nuclear reactors,

Protection of surfaces of steel products from corrosion,

In semiconductor technology,

Manufacturing of converters of thermal energy into electrical energy.

Nitrogen:

Gaseous:

For the production of ammonia,

To create an inert atmosphere when welding metals,

In vacuum installations,

Electric lamps,

Liquid:

As a refrigerant in freezers,

Medicine.

Phosphorus:

White - for the production of red phosphorus,

Red - for the production of matches.

Silicon:

IN electronics and electrical engineering for the manufacture of:

Schemes,

Diodes,

Transistors,

Photocells,

For the manufacture of alloys.

Chlorine:

Chloric acid production,

Organic solvents,

Medicines,

Monomers for the plastics industry,

Bleaches,

As a disinfectant.

Carbon:

Diamond:

Manufacturing of tools for drilling and cutting,

Abrasive material,

Jewelry,

Graphite:

Foundry, metallurgical, radio engineering production,

Battery manufacturing,

In the oil and gas industry for drilling operations,

Manufacturing of anti-corrosion coatings,

Friction reducing putty,

Adsorption.

Adsorption - the ability of some substances (in particular carbon) to hold particles of other substances (gas or solute) on their surface.

Its use in medicine for medicinal purposes is based on the adsorption capacity of carbon - these are tablets or capsules of activated carbon. They are used internally for poisoning.

To restore the adsorbent's ability to adsorb and remove the adsorbed substance, heating is sufficient.

The adsorption capacity of carbon was used by M.D. Zelinsky in a coal gas mask invented by him in 1915 - a means individual protection respiratory organs, face and eyes of a person from exposure to harmful substances. In 1916, the industrial production of gas masks was launched, which saved the lives of hundreds of thousands of soldiers during the First World War. The improved gas mask is still in use.

Homework

Write the reaction of interaction: a) silicon with oxygen; b) silicon with hydrogen; c) zinc with chlorine; d) phosphorus with chlorine. Name the compounds obtained.

Interaction with water

Many non-metals react with water to form oxides (and / or other compounds). Reactions take place with strong heating.

C + H 2 O → CO + H 2

6B + 6H 2 O → 2H 3 B 3 O 3 (boroxin) + 3H 2

4P + 10H 2 O → 2P 2 O 5 + 5H 2

3S + 2H 2 O → 2H 2 S + SO 2

Halogens, when interacting with water, disproportionate (form from a compound with one oxidation state compounds with different oxidation states) - except for F 2. The reactions take place at room temperature.

Cl 2 + H 2 O → HCl + HClO

Br 2 + H 2 O → HBr + HBrO

2F 2 + 2H 2 O → 4HF + O 2

Interaction with non-metals

Interaction with oxygen.

Most non-metals (except for halagens, noble gases) interact with oxygen to form oxides, and under certain conditions (temperature, pressure, catalysts), higher oxides.

N 2 + O 2 → 2NO (the reaction proceeds at a temperature of 2000 ° C or in an electric arc)

C + O 2 → CO 2

4B + 3O 2 → 2B 2 O 3

S + O 2 → SO 2

Interaction with fluorine

Most non-metals (except for N 2, C (diamond), some noble gases) interact with fluorine to form fluorides.

O 2 + 2F 2 → 2OF 2 (when passing electric current)

C + 2F 2 → CF 4 (at 900 ° C)

S + 3F 2 → SF 6

2.3 Interaction with halogens (Cl 2, Br 2)

With non-metals (except for carbon, nitrogen, fluorine, oxygen and inert gases), forms the corresponding halides (chlorides and bromides).

2S + Cl 2 → S 2 Cl 2

2S + Br 2 → S 2 Br 2

2P + 5Cl 2 → 2PCl 5 (combustion in chlorine atmosphere)

Cl 2 + Br 2 → 2BrCl

Cl 2 + I 2 → 2ICl (heating up to 45 ° C))

Br 2 + I 2 → 2IBr

Interaction with oxides

Carbon and silicon reduce metals and non-metals from their oxides. Reactions take place when heated.

SiO 2 + C \u003d CO 2 + Si

MnO2 + Si → Mn + SiO2.

Interaction with alkalis

Most non-metals (except F 2, Si) disproportionate when interacting with alkalis. Noble gases, O 2, N 2 and some other metals do not interact with alkalis

Cl 2 + 2NaOH → NaCl + NaClO

3Cl 2 + 6NaOH → 5NaCl + NaClO 3 + H 2 O (when heated)

3S + 6NaOH → 2Na 2 S + Na 2 SO 3 + 3H 2 O (fusion)

P + NaOH → Na 3 PO 3 + PH 3

Si + 2NaOH + H 2 O → Na 2 SiO 3 + 2H 2

4F 2 + 6NaOH → OF 2 + 6NaF + 3H 2 O + O 2

Interaction with oxidizing acids

All non-metals (except for halogens, noble gases, N 2, O 2, Si) interact with acids - oxidizing agents with the formation of the corresponding oxygenated acid (or oxide).

C + 2 H 2 SO 4 → CO 2 + 2SO 2 + 2H 2 O

B + 3HNO 3 → H 3 BO 3 + 3NO 2

S + 6HNO 3 → H 2 SO 4 + 6NO 2 + 2H 2 O

6interaction with salts

A more electronegative halogen displaces a less electronegative reagent from its salt or hydrogen compound

2NaBr + Cl 2 → 2NaCl + Br 2

Chemical properties non-oxide binary compounds are different. Most of them (except for halides), when interacting with oxygen, form two oxides (in the case of ammonia, catalysts must be used).

Chemical properties of basic oxides

Interaction with water

Oxides of alkali and alkaline earth metals interact with water to form soluble (poorly soluble) compounds - alkali

Na 2 O + H 2 O → 2NaOH

Interaction with oxides

Basic oxides react with acidic and amphoteric oxides to form salts.

Na 2 O + SO 3 → Na 2 SO 4

CaO + Al 2 O 3 → CaAl 2 O 4 (fusion)

5interactions with acids

Basic oxides interact with acids

CaO + 2HCl → CaCl 2 + H 2 O

FeO + 2HCl → FeCl 2 + H 2 O