What do metals interact with? General physical and chemical properties of metals

Chemical properties of metals: interaction with oxygen, halogens, sulfur and relation to water, acids, salts.

The chemical properties of metals are due to the ability of their atoms to easily give up electrons from an external energy level, turning into positively charged ions. Thus in chemical reactions metals are energetic reducing agents. This is their main common chemical property.

The ability to donate electrons in atoms of individual metallic elements is different. The more easily a metal gives up its electrons, the more active it is, and the more vigorously it reacts with other substances. Based on the research, all metals were arranged in a row according to their decreasing activity. This series was first proposed by the outstanding scientist N. N. Beketov. Such a series of activity of metals is also called the displacement series of metals or the electrochemical series of metal voltages. It looks like this:

Li, K, Ba, Ca, Na, Mg, Al, Zn, Fe, Ni, Sn, Pb, H2, Cu, Hg, Ag, Рt, Au

Using this series, you can find out which metal is the active of the other. This series contains hydrogen, which is not a metal. Its visible properties are taken for comparison as a kind of zero.

Having the properties of reducing agents, metals react with various oxidizing agents, primarily with non-metals. Metals react with oxygen under normal conditions or when heated to form oxides, for example:

2Mg0 + O02 = 2Mg+2O-2

In this reaction, magnesium atoms are oxidized and oxygen atoms are reduced. The noble metals at the end of the row react with oxygen. Reactions with halogens actively occur, for example, the combustion of copper in chlorine:

Cu0 + Cl02 = Cu+2Cl-2

Reactions with sulfur most often occur when heated, for example:

Fe0 + S0 = Fe+2S-2

Active metals in the activity series of metals in Mg react with water to form alkalis and hydrogen:

2Na0 + 2H+2O → 2Na+OH + H02

Metals of medium activity from Al to H2 react with water under more severe conditions and form oxides and hydrogen:

Pb0 + H+2O Chemical properties of metals: interaction with oxygen Pb+2O + H02.

The ability of a metal to react with acids and salts in solution also depends on its position in the displacement series of metals. Metals to the left of hydrogen in the displacement series of metals usually displace (reduce) hydrogen from dilute acids, and metals to the right of hydrogen do not displace it. So, zinc and magnesium react with acid solutions, releasing hydrogen and forming salts, while copper does not react.

Mg0 + 2H+Cl → Mg+2Cl2 + H02

Zn0 + H+2SO4 → Zn+2SO4 + H02.

Metal atoms in these reactions are reducing agents, and hydrogen ions are oxidizing agents.

Metals react with salts in aqueous solutions. Active metals displace less active metals from the composition of salts. This can be determined from the activity series of metals. The reaction products are new salt and new metal. So, if an iron plate is immersed in a solution of copper (II) sulfate, after a while copper will stand out on it in the form of a red coating:

Fe0 + Cu+2SO4 → Fe+2SO4 + Cu0 .

But if a silver plate is immersed in a solution of copper (II) sulfate, then no reaction will occur:

Ag + CuSO4 ≠ .

To carry out such reactions, one should not take too active metals (from lithium to sodium), which are capable of reacting with water.

Therefore, metals are able to react with non-metals, water, acids and salts. In all these cases, the metals are oxidized and are reducing agents. To predict the course of chemical reactions involving metals, a displacement series of metals should be used.

Reaction equations for the ratio of metals:

• a) to simple substances: oxygen, hydrogen, halogens, sulfur, nitrogen, carbon;
• b) to complex substances: water, acids, alkalis, salts.

1. Metals include s-elements of groups I and II, all s-elements, p-elements Group III(except for boron), as well as tin and lead (group IV), bismuth (group V) and polonium (group VI). Most metals have 1-3 electrons in their outer energy level. For atoms of d-elements inside the periods, from left to right, the d-sublevels of the pre-outer layer are filled.
2. The chemical properties of metals are due to the characteristic structure of their outer electron shells.

Within a period, with an increase in the charge of the nucleus, the radii of atoms with the same number of electron shells decrease. Alkali metal atoms have the largest radii. The smaller the atomic radius, the greater the ionization energy, and the larger the atomic radius, the lower the ionization energy. Since metal atoms have the largest atomic radii, they are characterized mainly by low values ​​of ionization energy and electron affinity. Free metals exhibit exclusively reducing properties.

3) Metals form oxides, for example:

Only alkali and alkaline earth metals react with hydrogen, forming hydrides:

Metals react with halogens to form halides, with sulfur - sulfides, with nitrogen - nitrides, with carbon - carbides.

With an increase in the algebraic value of the standard electrode potential of the metal E 0 in a series of voltages, the ability of the metal to react with water decreases. So, iron reacts with water only at very high temperature:

Metals with positive value standard electrode potential, that is, standing after hydrogen in a series of voltages, do not react with water.

Typical reactions of metals with acids. Metals with a negative value of E 0 displace hydrogen from solutions of Hcl, H 2 S0 4, H 3 P0 4, etc.

A metal with a lower value of E 0 displaces a metal with great value E 0 from salt solutions:

The most important calcium compounds obtained in industry, their chemical properties and methods of preparation.

Calcium oxide CaO is called quicklime. It is obtained by roasting limestone CaCO 3 --> CaO + CO, at a temperature of 2000 ° C. Calcium oxide has the properties of a basic oxide:

a) reacts with water to release a large number heat:

CaO + H 2 0 \u003d Ca (OH) 2 (slaked lime).

b) reacts with acids to form salt and water:

CaO + 2HCl \u003d CaCl 2 + H 2 O

CaO + 2H + = Ca 2+ + H 2 O

c) reacts with acid oxides to form a salt:

CaO + C0 2 \u003d CaC0 3

Calcium hydroxide Ca (OH) 2 is used in the form of slaked lime, milk of lime and lime water.

Lime milk is a suspension formed by mixing excess slaked lime with water.

Lime water is a clear solution obtained by filtering milk of lime. Used in the laboratory to detect carbon monoxide (IV).

Ca (OH) 2 + CO 2 \u003d CaCO 3 + H 2 O

With prolonged transmission of carbon monoxide (IV), the solution becomes transparent, since an acid salt is formed that is soluble in water:

CaC0 3 + C0 2 + H 2 O \u003d Ca (HCO 3) 2

If the resulting transparent solution of calcium bicarbonate is heated, then turbidity occurs again, since CaCO 3 precipitates:

Metals are active reducing agents with a positive oxidation state. Due to their chemical properties, metals are widely used in industry, metallurgy, medicine, and construction.

Metal Activity

In reactions, metal atoms donate valence electrons and are oxidized. The more energy levels and fewer electrons a metal atom has, the easier it is for it to donate electrons and enter into reactions. Therefore, metallic properties increase from top to bottom and from right to left in the periodic table.

Rice. 1. Change in metallic properties in the periodic table.

Activity simple substances shown in the electrochemical series of voltages of metals. To the left of hydrogen are active metals (activity increases towards the left edge), to the right - inactive.

Alkali metals in group I show the greatest activity. periodic table and standing to the left of hydrogen in the electrochemical series of voltages. They react with many substances already at room temperature. They are followed by alkaline earth metals, which are included in group II. They react with most substances when heated. Metals in the electrochemical series from aluminum to hydrogen (medium activity) require additional conditions to enter into a reaction.

Rice. 2. Electrochemical series of voltages of metals.

Some metals exhibit amphoteric properties or duality. Metals, their oxides and hydroxides react with acids and bases. Most metals only react with certain acids to replace the hydrogen and form a salt. The most pronounced dual properties show:

• aluminum;
• lead;
• zinc;
• iron;
• copper;
• beryllium;
• chromium.

Each metal is capable of displacing another metal to the right of it in the electrochemical series from salts. Metals to the left of hydrogen displace it from dilute acids.

Properties

Features of the interaction of metals with different substances are presented in the table of chemical properties of metals.

Metals interact with each other and form intermetallic compounds - 3Cu + Au → Cu 3 Au, 2Na + Sb → Na 2 Sb.

Application

General Chemical properties metals are used to create alloys, detergents are used in catalytic reactions. Metals are present in batteries, electronics, and load-bearing structures.

The main fields of application are indicated in the table.

Rice. 3. Bismuth.

What have we learned?

From the 9th grade chemistry lesson, we learned about the basic chemical properties of metals. The ability to interact with simple and complex substances determines the activity of metals. The more active the metal, the easier it reacts under normal conditions. Active metals react with halogens, non-metals, water, acids, salts. Amphoteric metals interact with alkalis. Inactive metals do not react with water, halogens, and most non-metals. Briefly reviewed the application areas. Metals are used in medicine, industry, metallurgy, and electronics.

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Restorative properties- These are the main chemical properties characteristic of all metals. They manifest themselves in interaction with a wide variety of oxidizing agents, including oxidizing agents from environment. AT general view the interaction of a metal with oxidizing agents can be expressed by the scheme:

Me + Oxidizer" Me(+X),

Where (+X) is the positive oxidation state of Me.

Examples of metal oxidation.

Fe + O 2 → Fe (+3) 4Fe + 3O 2 \u003d 2 Fe 2 O 3

Ti + I 2 → Ti(+4) Ti + 2I 2 = TiI 4

Zn + H + → Zn(+2) Zn + 2H + = Zn 2+ + H 2

1. Metals react with non-metals.

2Me+ n Hal 2 → 2 MeHal n

4Li + O2 = 2Li2O

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

2Na + O 2 \u003d Na 2 O 2

2. Metals standing up to hydrogen react with acids (except nitric and sulfuric conc.) with the release of hydrogen

Me + HCl → salt + H2

2 Al + 6 HCl → 2 AlCl3 + 3 H2

Pb + 2 HCl → PbCl2↓ + H2

3. Active metals react with water to form alkali and release hydrogen.

2Me+ 2n H 2 O → 2Me(OH) n + n H2

The product of metal oxidation is its hydroxide - Me (OH) n (where n is the oxidation state of the metal).

For example:

Ca + 2H 2 O → Ca (OH) 2 + H 2

4. Intermediate activity metals react with water when heated to form metal oxide and hydrogen.

2Me + nH 2 O → Me 2 O n + nH 2

The oxidation product in such reactions is metal oxide Me 2 O n (where n is the oxidation state of the metal).

3Fe + 4H 2 O → Fe 2 O 3 FeO + 4H 2

5. Metals standing after hydrogen do not react with water and acid solutions (except for nitric and sulfuric conc.)

6. More active metals displace less active ones from solutions of their salts.

CuSO 4 + Zn \u003d ZnSO 4 + Cu

CuSO 4 + Fe \u003d FeSO 4 + Cu

Active metals - zinc and iron replaced copper in sulfate and formed salts. Zinc and iron are oxidized, and copper is restored.

7. Halogens react with water and alkali solution.

Fluorine, unlike other halogens, oxidizes water:

2H 2 O+2F 2 = 4HF + O 2 .

in the cold: Cl2 + 2KOH = KClO + KCl + H2OCl2 + 2KOH = KClO + KCl + H2O chloride and hypochlorite are formed

heating: 3Cl2+6KOH−→KClO3+5KCl+3H2O3Cl2+6KOH→t,∘CKClO3+5KCl+3H2O forms loride and chlorate

8 Active halogens (except fluorine) displace less active halogens from solutions of their salts.

9. Halogens do not react with oxygen.

10. Amphoteric metals (Al, Be, Zn) react with solutions of alkalis and acids.

3Zn+4H2SO4= 3 ZnSO4+S+4H2O

11. Magnesium reacts with carbon dioxide and silicon oxide.

2Mg + CO2 = C + 2MgO

SiO2+2Mg=Si+2MgO

12. Alkali metals (except lithium) form peroxides with oxygen.

2Na + O 2 \u003d Na 2 O 2

3. Classification of inorganic compounds

Simple substances - substances whose molecules consist of atoms of the same type (atoms of the same element). In chemical reactions, they cannot decompose to form other substances.

Complex Substances (or chemical compounds) - substances whose molecules consist of atoms of different types (atoms of various chemical elements). In chemical reactions, they decompose to form several other substances.

Simple substances are divided into two large groups: metals and non-metals.

Metals - a group of elements with characteristic metallic properties: solids (with the exception of mercury) have a metallic luster, are good conductors of heat and electricity, malleable (iron (Fe), copper (Cu), aluminum (Al), mercury (Hg), gold (Au), silver (Ag), etc.).

non-metals – a group of elements: solid, liquid (bromine) and gaseous substances, which do not have a metallic sheen, are insulators, brittle.

BUT complex substances In turn, they are divided into four groups, or classes: oxides, bases, acids and salts.

oxides - These are complex substances, the composition of the molecules of which includes atoms of oxygen and some other substance.

Foundations - These are complex substances in which metal atoms are connected to one or more hydroxyl groups.

From the point of view of the theory of electrolytic dissociation, bases are complex substances, the dissociation of which in an aqueous solution produces metal cations (or NH4 +) and hydroxide - anions OH-.

acids - these are complex substances whose molecules include hydrogen atoms that can be replaced or exchanged for metal atoms.

salt - These are complex substances, the molecules of which consist of metal atoms and acid residues. Salt is a product of partial or complete replacement of hydrogen atoms of an acid by a metal.