Interaction of metals with simple substances non-metals. Metals: general characteristics of metals and alloys
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.
- 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.
- 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 alkaline and alkaline earth metals, 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 temperatures:
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 with the release of a large amount of 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:
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). AT chemical reactions 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.
The structure of metal atoms determines not only the characteristic physical properties of simple substances - metals, but also their general chemical properties.
With a large variety, all chemical reactions of metals are redox and can only be of two types: compounds and substitutions. Metals are able to donate electrons during chemical reactions, that is, to be reducing agents, to show only a positive oxidation state in the compounds formed.
AT general view this can be expressed in a diagram:
Me 0 - ne → Me + n,
where Me - metal - a simple substance, and Me 0 + n - metal chemical element in the compound.
Metals are able to donate their valence electrons to atoms of non-metals, hydrogen ions, ions of other metals, and therefore will react with non-metals - simple substances, water, acids, salts. However, the reducing ability of metals is different. The composition of the reaction products of metals with various substances also depends on the oxidizing ability of the substances and the conditions under which the reaction proceeds.
At high temperatures most metals burn in oxygen:
2Mg + O 2 \u003d 2MgO
Only gold, silver, platinum and some other metals do not oxidize under these conditions.
Many metals react with halogens without heating. For example, aluminum powder, when mixed with bromine, ignites:
2Al + 3Br 2 = 2AlBr 3
When metals interact with water, hydroxides are sometimes formed. Alkali metals, as well as calcium, strontium, barium, interact very actively with water under normal conditions. The general scheme of this reaction looks like this:
Me + HOH → Me(OH) n + H 2
Other metals react with water when heated: magnesium when it boils, iron in water vapor when it boils red. In these cases, metal oxides are obtained.
If the metal reacts with an acid, then it is part of the resulting salt. When a metal interacts with acid solutions, it can be oxidized by the hydrogen ions present in that solution. The abbreviated ionic equation in general form can be written as follows:
Me + nH + → Me n + + H 2
Anions of such oxygen-containing acids, such as concentrated sulfuric and nitric acids, have stronger oxidizing properties than hydrogen ions. Therefore, those metals that are not able to be oxidized by hydrogen ions, such as copper and silver, react with these acids.
When metals interact with salts, a substitution reaction occurs: electrons from the atoms of the substituting - more active metal pass to the ions of the substituting - less active metal. Then the network replaces metal with metal in salts. These reactions are not reversible: if metal A displaces metal B from the salt solution, then metal B will not displace metal A from the salt solution.
In descending order of chemical activity, manifested in the reactions of displacement of metals from each other from aqueous solutions their salts, metals are located in the electrochemical series of voltages (activity) of metals:
Li → Rb → K → Ba → Sr → Ca → Na→ Mg → Al → Mn → Zn → Cr → → Fe → Cd→ Co → Ni → Sn → Pb → H → Sb → Bi → Cu → Hg → Ag → Pd → Pt → Au
The metals located to the left of this row are more active and are able to displace the metals following them from salt solutions.
Hydrogen is included in the electrochemical series of voltages of metals, as the only non-metal that shares a common property with metals - to form positively charged ions. Therefore, hydrogen replaces some metals in their salts and can itself be replaced by many metals in acids, for example:
Zn + 2 HCl \u003d ZnCl 2 + H 2 + Q
Metals standing in the electrochemical series of voltages up to hydrogen displace it from solutions of many acids (hydrochloric, sulfuric, etc.), and all following it, for example, do not displace copper.
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The first material that people learned to use for their needs is stone. However, later, when a person became aware of the properties of metals, the stone moved far back. It is these substances and their alloys that have become the most important and main material in the hands of people. Household items, tools of labor were made from them, premises were built. Therefore, in this article we will consider what metals are, general characteristics, the properties and application of which are so relevant to this day. Indeed, literally immediately after stone age a whole galaxy of metal ones followed: copper, bronze and iron.
Metals: general characteristics
What unites all representatives of these simple substances? Of course, this is the structure of their crystal lattice, types of chemical bonds and features of the electronic structure of the atom. After all, hence the characteristic physical properties that underlie the use of these materials by humans.
First of all, consider metals as chemical elements periodic system. In it, they are located quite freely, occupying 95 cells out of 115 known today. There are several features of their location in the general system:
- They form the main subgroups of groups I and II, as well as III, starting with aluminum.
- All side subgroups consist only of metals.
- They are located below the conditional diagonal from boron to astatine.
Based on such data, it is easy to see that non-metals are collected in the upper right part of the system, and the rest of the space belongs to the elements we are considering.
All of them have several features of the electronic structure of the atom:
The general characteristics of metals and non-metals makes it possible to identify patterns in their structure. So, the crystal lattice of the first is metallic, special. Its nodes contain several types of particles at once:
- ions;
- atoms;
- electrons.
A common cloud accumulates inside, called electron gas, which explains all the physical properties of these substances. The type of chemical bond in metals is of the same name with them.
Physical properties
There are a number of parameters that unite all metals. Their general characteristics according to physical properties looks like that.
The listed parameters are the general characteristics of metals, that is, everything that unites them into one large family. However, it should be understood that there are exceptions to every rule. Moreover, there are too many elements of this kind. Therefore, within the family itself there are also divisions into various groups, which we will consider below and for which we will indicate the characteristic features.
Chemical properties
From the point of view of the science of chemistry, all metals are reducing agents. And, very strong. The fewer electrons external level and the larger the atomic radius, the stronger the metal according to the specified parameter.
As a result, metals are able to react with:
This is just a general overview of chemical properties. After all, for each group of elements they are purely individual.
alkaline earth metals
The general characteristics of alkaline earth metals are as follows:
Thus, alkaline earth metals are common elements of the s-family, exhibiting high chemical activity and are strong reducing agents and important participants in biological processes in the body.
alkali metals
The general characteristic begins with their name. They received it for the ability to dissolve in water, forming alkalis - caustic hydroxides. Reactions with water are very violent, sometimes flammable. These substances are not found in free form in nature, since their chemical activity is too high. They react with air, water vapor, non-metals, acids, oxides and salts, that is, with almost everything.
This is explained by their electronic structure. At the outer level, there is only one electron, which they easily give away. These are the most powerful reducing agents, which is why to obtain them in pure form it took quite a long time. This was first done by Humphrey Davy already in the 18th century by electrolysis of sodium hydroxide. Now all representatives of this group are mined using this method.
The general characteristic of alkali metals is also that they constitute the first group of the main subgroup of the periodic system. All of them - important elements, which form many valuable natural compounds used by man.
General characteristics of metals of d- and f-families
This group of elements includes all those whose oxidation state can vary. This means that, depending on the conditions, the metal can act as both an oxidizing agent and a reducing agent. Such elements have a great ability to enter into reactions. Among them a large number of amphoteric substances.
The common name for all these atoms is transition elements. They received it for the fact that, in terms of their properties, they really stand, as it were, in the middle, between typical metals of the s-family and non-metals of the p-family.
The general characteristic of transition metals implies the designation of their similar properties. They are the following:
- a large number of electrons in the outer level;
- large atomic radius;
- several degrees of oxidation (from +3 to +7);
- are on the d- or f-sublevel;
- form 4-6 large periods of the system.
As simple substances, the metals of this group are very strong, ductile and malleable, therefore they are of great industrial importance.
Side subgroups of the periodic system
The general characteristics of the metals of the secondary subgroups completely coincide with those of the transitional ones. And this is not surprising, because, in fact, it is exactly the same thing. It's just that the side subgroups of the system are formed precisely by representatives of the d- and f-families, that is, transition metals. Therefore, we can say that these concepts are synonyms.
The most active and important of them are the first row of 10 representatives from scandium to zinc. All of them are of great industrial importance and are often used by man, especially for smelting.
Alloys
The general characteristics of metals and alloys makes it possible to understand where and how it is possible to use these substances. Such compounds have undergone great transformations in the last decades, because more and more new additives are being discovered and synthesized to improve their quality.
The most famous alloys today are:
- brass;
- duralumin;
- cast iron;
- steel;
- bronze;
- will win;
- nichrome and others.
What is an alloy? This is a mixture of metals obtained by smelting the latter in special furnace devices. This is done in order to obtain a product that is superior in properties to the pure substances that form it.
Comparison of properties of metals and non-metals
If we talk about general properties, then the characteristics of metals and non-metals will differ in one very significant point: for the latter, similar features cannot be distinguished, since they differ greatly in their manifested properties, both physical and chemical.
Therefore, it is impossible to create such a characteristic for non-metals. It is only possible to separately consider the representatives of each group and describe their properties.
INTERACTION OF METALS WITH NONMETALS
Non-metals exhibit oxidizing properties in reactions with metals, accepting electrons from them and recovering.
Interaction with halogens
Halogens (F 2, Cl 2, Br 2, I 2 ) are strong oxidizing agents, therefore, all metals interact with them under normal conditions:
2Me+ n Hal 2 → 2 MeHal n
The product of this reaction is a metal halide salt ( MeF n -fluoride, MeCl n -chloride, MeBr n -bromide, MeI n -iodide). When interacting with a metal, the halogen is reduced to the lowest oxidation state (-1), andnequal to the oxidation state of the metal.
The reaction rate depends on the chemical activity of the metal and halogen. The oxidative activity of halogens decreases in the group from top to bottom (from F to I ).
Interaction with oxygen
Oxygen oxidizes almost all metals (except Ag, Au, Pt ), resulting in the formation of oxides Me 2 O n .
active metals easily interact with atmospheric oxygen under normal conditions.
2 Mg + O 2 → 2 MgO (with flash)
Intermediate activity metals also react with oxygen at ordinary temperature. But the rate of such a reaction is significantly lower than with the participation of active metals.
Inactive metals oxidized by oxygen when heated (combustion in oxygen).
oxides Chemical properties of metals can be divided into three groups:
1. Basic oxides ( Na 2 O, CaO, Fe II O, Mn II O, Cu I O etc.) are formed by metals in low oxidation states (+1, +2, as a rule, below +4). Basic oxides interact with acidic oxides and acids to form salts:
CaO + CO 2 → CaCO 3
CuO + H 2 SO 4 → CuSO 4 + H 2 O
2. Acid oxides ( Cr VI O 3 , Fe VI O 3 , Mn VI O 3 , Mn 2 VII O 7 etc.) are formed by metals in high oxidation states (as a rule, above +4). Acid oxides interact with basic oxides and bases to form salts:
FeO 3 + K 2 O → K 2 FeO 4
CrO 3 + 2KOH → K 2 CrO 4 + H 2 O
3. Amphoteric oxides ( BeO, Al 2 O 3, ZnO, SnO, MnO 2, Cr 2 O 3, PbO, PbO 2 etc.) have a dual nature and can interact with both acids and bases:
Cr 2 O 3 + 3H 2 SO 4 → Cr 2 (SO 4) + 3H 2 O
Cr 2 O 3 + 6NaOH → 2Na 3
Interaction with sulfur
All metals interact with sulfur (except Au ), forming salts - sulfides Me 2 S n . In this case, sulfur is reduced to the oxidation state of "-2". Platinum ( Pt ) interacts with sulfur only in a finely divided state. alkali metals, and Ca and Mg react with sulfur when heated with an explosion. Zn, Al (powder) and Mg in reaction with sulfur give a flash. In the direction from left to right in the activity series, the rate of interaction of metals with sulfur decreases.
Interaction with hydrogen
With hydrogen, some active metals form compounds - hydrides:
2 Na + H 2 → 2 NaH
In these compounds, hydrogen is in its rare oxidation state "-1".
E.A. Nudnova, M.V. Andriukhova