Amphoteric metals chemical properties. amphoteric metals

Amphoteric metals are simple substances that are structurally, chemically and similar to the metal group of elements. Metals themselves cannot exhibit amphoteric properties, unlike their compounds. For example, the oxides and hydroxides of some metals have a dual chemical nature - in some conditions they behave like acids, while in others they have the properties of alkalis.

The main amphoteric metals are aluminum, zinc, chromium, and iron. Beryllium and strontium can be attributed to the same group of elements.

amphoteric?

For the first time this property was discovered quite a long time ago. And the term "amphoteric elements" was introduced into science in 1814 by the famous chemists L. Tenard and J. Gay-Lussac. In those days, it was customary to divide chemical compounds into groups that corresponded to their basic properties during reactions.

However, the group of oxides and bases had dual abilities. Under some conditions, such substances behaved like alkalis, while in others, on the contrary, they acted like acids. This is how the term "amphoteric" was born. For such, the behavior during the acid-base reaction depends on the conditions of its implementation, the nature of the reagents involved, and also on the properties of the solvent.

Interestingly, under natural conditions, amphoteric metals can interact with both alkali and acid. For example, during the reaction of aluminum with aluminum sulfate is formed. And when the same metal reacts with concentrated alkali, a complex salt is formed.

Amphoteric bases and their main properties

Under normal conditions, these are solids. They are practically insoluble in water and are considered rather weak electrolytes.

The main method for obtaining such bases is the reaction of a metal salt with a small amount of alkali. The precipitation reaction must be carried out slowly and carefully. For example, when receiving zinc hydroxide, caustic soda is carefully added in drops to a test tube with zinc chloride. Each time you need to gently shake the container to see the white precipitate of metal at the bottom of the dish.

With acids and amphoteric substances react as bases. For example, the reaction of zinc hydroxide with hydrochloric acid produces zinc chloride.

But during reactions with bases, amphoteric bases behave like acids.

In addition, when strongly heated, they decompose to form the corresponding amphoteric oxide and water.

The most common amphoteric metals: a brief description

Zinc belongs to the group of amphoteric elements. And although alloys of this substance were widely used in ancient civilizations, it was only in 1746 that they could isolate it in its pure form.

Pure metal is a rather brittle bluish substance. Zinc rapidly oxidizes in air - its surface tarnishes and becomes covered with a thin film of oxide.

In nature, zinc exists mainly in the form of minerals - zincites, smithsonites, calamites. The most famous substance is zinc blende, which consists of zinc sulfide. The largest deposits of this mineral are in Bolivia and Australia.

Aluminum Today it is considered the most common metal on the planet. Its alloys have been used for many centuries, and in 1825 the substance was isolated in its pure form.

Pure aluminum is a light, silver-colored metal. It is easy to machine and cast. This element has high electrical and thermal conductivity. In addition, this metal is resistant to corrosion. The fact is that its surface is covered with a thin, but very resistant oxide film.

Today, aluminum is widely used in industry.

Amphoteric oxides react with strong acids to form salts of these acids. Such reactions are a manifestation of the main properties of amphoteric oxides, for example:

ZnO + H 2 SO 4 → ZnSO 4 + H 2 O

They also react with strong alkalis, thereby showing their acidic properties, for example:

ZnO + 2NaOH → Na 2 ZnO 2 + H 2 O Amphoteric oxides can react with alkalis in two ways: in solution and in melt.

When reacting with an alkali in the melt, an ordinary medium salt is formed (as shown in the example above).
When reacting with alkali in solution, a complex salt is formed.

Al 2 O 3 + 2NaOH + 3H 2 O → 2Na (In this case, sodium tetrahydroxoalluminate is formed)

Each amphoteric metal has its own coordination number. For Be and Zn, this is 4; For Al, this is 4 or 6; For Cr it is 6 or (very rarely) 4;

Amphoteric oxides usually do not dissolve in water and do not react with it.

Examples

What are amphoteric metals

The list of metals that can be classified as amphoteric is quite large. Moreover, some of them can be called amphoteric, and some - conditionally.

Let's list the serial numbers of the substances under which they are located in the Periodic Table. The list includes groups 22 to 32, 40 to 51 and many more. For example, chromium, iron and a number of others can rightfully be called basic, and strontium and beryllium can also be attributed to the latter.

By the way, aluminum is considered the brightest representative of amphora metals.

It is its alloys that have been used for a long time in almost all industries. It is used to make elements of aircraft fuselages, car bodies, and kitchen utensils. It has become indispensable in the electrical industry and in the production of equipment for heating networks. Unlike many other metals, aluminum is constantly reactive. The oxide film that covers the surface of the metal resists oxidative processes. Under normal conditions, and in certain types of chemical reactions, aluminum can act as a reducing element.

This metal is able to interact with oxygen if it is crushed into many small particles. This type of operation requires the use of high temperatures. The reaction is accompanied by the release of a large amount of thermal energy. When the temperature rises to 200 ºC, aluminum reacts with sulfur. The thing is that aluminum, not always, under normal conditions, can react with hydrogen. Meanwhile, when it is mixed with other metals, different alloys can occur.

Another pronounced amphoteric metal is iron. This element has the number 26 and is located between cobalt and manganese. Iron is the most common element found in the earth's crust. Iron can be classified as a simple element, having a silvery white color and malleable, of course, when exposed to high temperatures. Can quickly begin to corrode at high temperatures. Iron, if placed in pure oxygen, completely burns out and can ignite in the open air.

Such a metal has the ability to quickly go into the stage of corrosion when exposed to high temperatures. Iron placed in pure oxygen completely burns out. Being in the air, a metallic substance quickly oxidizes due to excessive moisture, that is, it rusts. When burning in an oxygen mass, a kind of scale is formed, which is called iron oxide.

Properties of amphoteric metals

They are defined by the very concept of amphotericity. In the typical state, that is, at normal temperature and humidity, most metals are solids. None of the metals can be dissolved in water. Alkaline bases appear only after certain chemical reactions. In the course of the reaction, metal salts interact. It should be noted that safety rules require special care when carrying out this reaction.

The combination of amphoteric substances with oxides or acids themselves is the first to show the reaction that is inherent in bases. At the same time, if they are combined with bases, acidic properties will appear.

Heating amphoteric hydroxides causes them to decompose into water and oxide. In other words, the properties of amphoteric substances are very wide and require careful study, which can be carried out during a chemical reaction.

The properties of amphoteric elements can be understood by comparing them with the parameters of traditional materials. For example, most metals have a low ionization potential and this allows them to act as reducing agents in chemical processes.

Amphoteric - can show both reducing and oxidizing characteristics. However, there are compounds that are characterized by a negative level of oxidation.

Absolutely all known metals have the ability to form hydroxides and oxides.

All metals have the ability to form basic hydroxides and oxides. By the way, metals can enter into an oxidation reaction only with certain acids. For example, the reaction with nitric acid can proceed in different ways.

Amphoteric substances related to simple ones have clear differences in structure and features. Belonging to a certain class can be determined at a glance for some substances, so it is immediately clear that copper is a metal, but bromine is not.

How to distinguish metal from non-metal

The main difference is that metals donate electrons that are in an external electron cloud. Non-metals actively attract them.

All metals are good conductors of heat and electricity, non-metals are deprived of such an opportunity.

Bases of amphoteric metals

Under normal conditions, these substances do not dissolve in water and can be safely attributed to weak electrolytes. Such substances are obtained after the reaction of metal salts and alkali. These reactions are quite dangerous for those who produce them, and therefore, for example, to obtain zinc hydroxide, caustic soda must be slowly and carefully introduced into a container with zinc chloride, drop by drop.

At the same time, amphoteric - interact with acids as bases. That is, when performing a reaction between hydrochloric acid and zinc hydroxide, zinc chloride will appear. And when interacting with bases, they behave like acids.

Bases, amphoteric hydroxides

Bases are complex substances consisting of metal atoms and one or more hydroxo groups (-OH). The general formula is Me + y (OH) y, where y is the number of hydroxo groups equal to the oxidation state of the metal Me. The table shows the classification of bases.

Properties of alkali hydroxides of alkali and alkaline earth metals

1. Aqueous solutions of alkalis are soapy to the touch, change the color of indicators: litmus - blue, phenolphthalein - raspberry.

2. Aqueous solutions dissociate:

3. Interact with acids, entering into an exchange reaction:

Polyacid bases can give intermediate and basic salts:

4. Interact with acid oxides, forming medium and acid salts, depending on the basicity of the acid corresponding to this oxide:

5. Interact with amphoteric oxides and hydroxides:

a) fusion:

b) in solutions:

6. React with water-soluble salts if a precipitate or gas is formed:

Insoluble bases (Cr (OH) 2, Mn (OH) 2, etc.) interact with acids and decompose when heated:

Amphoteric hydroxides

Compounds are called amphoteric, which, depending on the conditions, can be both donors of hydrogen cations and exhibit acidic properties, and their acceptors, i.e., exhibit basic properties.

Chemical properties of amphoteric compounds

1. Interacting with strong acids, they reveal the main properties:

Zn(OH) 2 + 2HCl = ZnCl 2 + 2H 2 O

2. Interacting with alkalis - strong bases, they exhibit acidic properties:

Zn (OH) 2 + 2NaOH \u003d Na 2 ( complex salt)

Al (OH) 3 + NaOH \u003d Na ( complex salt)

Compounds are called complex in which at least one covalent bond was formed by the donor-acceptor mechanism.

The general method for obtaining bases is based on exchange reactions, by which both insoluble and soluble bases can be obtained.

CuSO 4 + 2KOH \u003d Cu (OH) 2 ↓ + K 2 SO 4

K 2 CO 3 + Ba (OH) 2 \u003d 2 KOH + BaCO 3 ↓

When soluble bases are obtained by this method, an insoluble salt precipitates.

When obtaining water-insoluble bases with amphoteric properties, an excess of alkali should be avoided, since dissolution of the amphoteric base may occur, for example:

AlCl 3 + 4KOH \u003d K [Al (OH) 4] + 3KSl

In such cases, ammonium hydroxide is used to obtain hydroxides, in which amphoteric hydroxides do not dissolve:

AlCl 3 + 3NH 3 + ZH 2 O \u003d Al (OH) 3 ↓ + 3NH 4 Cl

Hydroxides of silver and mercury decompose so easily that when you try to obtain them by an exchange reaction, instead of hydroxides, oxides precipitate:

2AgNO 3 + 2KOH \u003d Ag 2 O ↓ + H 2 O + 2KNO 3

In industry, alkalis are usually obtained by electrolysis of aqueous solutions of chlorides.

2NaCl + 2H 2 O → ϟ → 2NaOH + H 2 + Cl 2

Alkalis can also be obtained by reacting alkali and alkaline earth metals or their oxides with water.

2Li + 2H 2 O \u003d 2LiOH + H 2

SrO + H 2 O \u003d Sr (OH) 2

acids

Acids are called complex substances, the molecules of which consist of hydrogen atoms that can be replaced by metal atoms, and acid residues. Under normal conditions, acids can be solid (phosphoric H 3 PO 4; silicon H 2 SiO 3) and liquid (sulfuric acid H 2 SO 4 will be a pure liquid).

Gases such as hydrogen chloride HCl, hydrogen bromide HBr, hydrogen sulfide H 2 S form the corresponding acids in aqueous solutions. The number of hydrogen ions formed by each acid molecule during dissociation determines the charge of the acid residue (anion) and the basicity of the acid.

According to protolytic theory of acids and bases, proposed simultaneously by the Danish chemist Bronsted and the English chemist Lowry, an acid is a substance splitting off with this reaction protons, a basis- a substance capable of receive protons.

acid → base + H +

Based on these ideas, it is clear basic properties of ammonia, which, due to the presence of a lone electron pair at the nitrogen atom, effectively accepts a proton when interacting with acids, forming an ammonium ion through a donor-acceptor bond.

HNO 3 + NH 3 ⇆ NH 4 + + NO 3 -

acid base acid base

A more general definition of acids and bases proposed by the American chemist G. Lewis. He suggested that acid-base interactions are quite do not necessarily occur with protone transfer. In the determination of acids and bases according to Lewis, the main role in chemical reactions is given to electronic steam.

Cations, anions, or neutral molecules that can accept one or more pairs of electrons are called Lewis acids.

For example, aluminum fluoride AlF 3 is an acid, since it is able to accept an electron pair when interacting with ammonia.

AlF 3 + :NH 3 ⇆ :

Cations, anions or neutral molecules capable of donating electron pairs are called Lewis bases (ammonia is a base).

The Lewis definition covers all acid-base processes that have been considered by the previously proposed theories. The table compares the definitions of acids and bases currently in use.

Nomenclature of acids

Since there are different definitions of acids, their classification and nomenclature are rather arbitrary.

According to the number of hydrogen atoms capable of splitting off in an aqueous solution, acids are divided into monobasic(e.g. HF, HNO 2), dibasic(H 2 CO 3 , H 2 SO 4) and tribasic(H 3 RO 4).

According to the composition of the acid is divided into anoxic(HCl, H 2 S) and oxygen-containing(HClO 4 , HNO 3).

Usually names of oxygenated acids derived from the name of a non-metal with the addition of the endings -kai, -way, if the oxidation state of the non-metal is equal to the group number. As the oxidation state decreases, the suffixes change (in order of decreasing metal oxidation state): - oval, ististaya, - ovate:

If we consider the polarity of the hydrogen-non-metal bond within a period, we can easily relate the polarity of this bond to the position of the element in the Periodic Table. From metal atoms that easily lose valence electrons, hydrogen atoms accept these electrons, forming a stable two-electron shell like the shell of a helium atom, and give ionic metal hydrides.

In hydrogen compounds of elements of groups III-IV of the Periodic system, boron, aluminum, carbon, silicon form covalent, weakly polar bonds with hydrogen atoms that are not prone to dissociation. For elements of groups V-VII of the Periodic system, within a period, the polarity of the non-metal-hydrogen bond increases with the charge of the atom, but the distribution of charges in the resulting dipole is different than in hydrogen compounds of elements that tend to donate electrons. Atoms of non-metals, in which several electrons are needed to complete the electron shell, pull towards themselves (polarize) a pair of bond electrons the stronger, the greater the charge of the nucleus. Therefore, in the series CH 4 - NH 3 - H 2 O - HF or SiH 4 - PH 3 - H 2 S - Hcl, bonds with hydrogen atoms, while remaining covalent, become more polar, and the hydrogen atom in the element-hydrogen bond dipole becomes more electropositive. If polar molecules are in a polar solvent, the process of electrolytic dissociation can occur.

Let us discuss the behavior of oxygen-containing acids in aqueous solutions. These acids have an H-O-E bond and, naturally, the O-E bond affects the polarity of the H-O bond. Therefore, these acids dissociate, as a rule, more easily than water.

H 2 SO 3 + H 2 O ⇆ H s O + + HSO 3

HNO 3 + H 2 O ⇆ H s O + + NO 3

Let's look at a few examples properties of oxygenated acids, formed by elements that are capable of exhibiting different oxidation states. It is known that hypochlorous acid HClO very weak hydrochloric acid HClO 2 also weak but stronger than hypochlorous, hypochlorous acid HclO 3 strong. Perchloric acid HClO 4 is one of the the strongest inorganic acids.

Dissociation according to the acidic type (with the elimination of the H ion) requires breaking the O-H bond. How can one explain the decrease in the strength of this bond in the series HClO - HClO 2 - HClO 3 - HClO 4? In this series, the number of oxygen atoms associated with the central chlorine atom increases. Each time a new bond of oxygen with chlorine is formed, an electron density is drawn away from the chlorine atom, and hence from the single O-Cl bond. As a result, the electron density partially leaves the О-Н bond, which is weakened because of this.

Such a pattern - enhancement of acidic properties with an increase in the degree of oxidation of the central atom - characteristic not only for chlorine, but also for other elements. For example, nitric acid HNO 3 , in which the nitrogen oxidation state is +5, is stronger than nitrous acid HNO 2 (nitrogen oxidation state is +3); sulfuric acid H 2 SO 4 (S +6) is stronger than sulfurous acid H 2 SO 3 (S +4).

Obtaining acids

1. Anoxic acids can be obtained in the direct combination of non-metals with hydrogen.

H 2 + Cl 2 → 2HCl,

H 2 + S ⇆ H 2 S

2. Some oxygenated acids can be obtained interaction of acid oxides with water.

3. Both anoxic and oxygenated acids can be obtained according to exchange reactions between salts and other acids.

BaBr 2 + H 2 SO 4 \u003d BaSO 4 ↓ + 2HBr

CuSO 4 + H 2 S \u003d H 2 SO 4 + CuS ↓

FeS + H 2 SO 4 (pa zb) \u003d H 2 S + FeSO 4

NaCl (T) + H 2 SO 4 (conc) = HCl + NaHSO 4

AgNO 3 + HCl = AgCl↓ + HNO 3

CaCO 3 + 2HBr \u003d CaBr 2 + CO 2 + H 2 O

4. Some acids can be obtained using redox reactions.

H 2 O 2 + SO 2 \u003d H 2 SO 4

3P + 5HNO 3 + 2H 2 O \u003d ZH 3 PO 4 + 5NO 2

Sour taste, action on indicators, electrical conductivity, interaction with metals, basic and amphoteric oxides, bases and salts, formation of esters with alcohols - these properties are common to inorganic and organic acids.

can be divided into two types of reactions:

1) general for acids the reactions are associated with the formation of hydronium ion H 3 O + in aqueous solutions;

2) specific(i.e. characteristic) reactions specific acids.

The hydrogen ion can enter into redox reactions, reducing to hydrogen, as well as in a compound reaction with negatively charged or neutral particles having lone pairs of electrons, i.e. in acid-base reactions.

The general properties of acids include the reactions of acids with metals in the series of voltages up to hydrogen, for example:

Zn + 2Н + = Zn 2+ + Н 2

Acid-base reactions include reactions with basic oxides and bases, as well as with medium, basic, and sometimes acidic salts.

2 CO 3 + 4HBr \u003d 2CuBr 2 + CO 2 + 3H 2 O

Mg (HCO 3) 2 + 2HCl \u003d MgCl 2 + 2CO 2 + 2H 2 O

2KHSO 3 + H 2 SO 4 \u003d K 2 SO 4 + 2SO 2 + 2H 2 O

Note that polybasic acids dissociate stepwise, and at each next step, dissociation is more difficult, therefore, with an excess of acid, acidic salts are most often formed, rather than medium ones.

Ca 3 (PO 4) 2 + 4H 3 PO 4 \u003d 3Ca (H 2 PO 4) 2

Na 2 S + H 3 PO 4 = Na 2 HPO 4 + H 2 S

NaOH + H 3 PO 4 = NaH 2 PO 4 + H 2 O

KOH + H 2 S \u003d KHS + H 2 O

At first glance, the formation of acidic salts may seem surprising. monobasic hydrofluoric (hydrofluoric) acid. However, this fact can be explained. Unlike all other hydrohalic acids, hydrofluoric acid is partially polymerized in solutions (due to the formation of hydrogen bonds) and different particles (HF) X can be present in it, namely H 2 F 2, H 3 F 3, etc.

A special case of acid-base balance - reactions of acids and bases with indicators that change color depending on the acidity of the solution. Indicators are used in qualitative analysis to detect acids and bases in solutions.

The most commonly used indicators are litmus(in neutral environment purple, in sour - red, in alkaline - blue), methyl orange(in sour environment red, in neutral - orange, in alkaline - yellow), phenolphthalein(in strongly alkaline environment crimson red, in neutral and acidic - colorless).

Specific Properties different acids can be of two types: first, the reactions leading to the formation insoluble salts, and, secondly, redox transformations. If the reactions associated with the presence of an H + ion in them are common to all acids (qualitative reactions for detecting acids), specific reactions are used as qualitative reactions for individual acids:

Ag + + Cl - = AgCl (white precipitate)

Ba 2+ + SO 4 2- \u003d BaSO 4 (white precipitate)

3Ag + + PO 4 3 - = Ag 3 PO 4 (yellow precipitate)

Some specific reactions of acids are due to their redox properties.

Anoxic acids in aqueous solution can only oxidize.

2KMnO 4 + 16HCl \u003d 5Cl 2 + 2KCl + 2MnCl 2 + 8H 2 O

H 2 S + Br 2 \u003d S + 2HBg

Oxygen-containing acids can only be oxidized if the central atom in them is in a lower or intermediate oxidation state, as, for example, in sulfurous acid:

H 2 SO 3 + Cl 2 + H 2 O \u003d H 2 SO 4 + 2HCl

Many oxygen-containing acids, in which the central atom has the maximum oxidation state (S +6, N +5, Cr +6), exhibit the properties of strong oxidizing agents. Concentrated H 2 SO 4 is a strong oxidizing agent.

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

Pb + 4HNO 3 \u003d Pb (NO 3) 2 + 2NO 2 + 2H 2 O

C + 2H 2 SO 4 (conc) = CO 2 + 2SO 2 + 2H 2 O

It should be remembered that:

Acid solutions react with metals that are in the electrochemical series of voltages to the left of hydrogen, subject to a number of conditions, the most important of which is the formation of a soluble salt as a result of the reaction. The interaction of HNO 3 and H 2 SO 4 (conc.) with metals proceeds differently.

Concentrated sulfuric acid in the cold passivates aluminum, iron, chromium.

In water, acids dissociate into hydrogen cations and anions of acid residues, for example:

Inorganic and organic acids interact with basic and amphoteric oxides, provided that a soluble salt is formed:

Both those and other acids react with bases. Polybasic acids can form both medium and acidic salts (these are neutralization reactions):

The reaction between acids and salts occurs only if a precipitate or gas is formed:

The interaction of H 3 PO 4 with limestone will stop due to the formation of the last insoluble precipitate Ca 3 (PO 4) 2 on the surface.

The features of the properties of nitric HNO 3 and concentrated sulfuric H 2 SO 4 (conc.) acids are due to the fact that when they interact with simple substances (metals and non-metals), not H + cations, but nitrate and sulfate ions will act as oxidizing agents. It is logical to expect that as a result of such reactions, not hydrogen H 2 is formed, but other substances are obtained: necessarily salt and water, as well as one of the products of the reduction of nitrate or sulfate ions, depending on the concentration of acids, the position of the metal in a series of voltages and reaction conditions (temperature, metal fineness, etc.).

These features of the chemical behavior of HNO 3 and H 2 SO 4 (conc.) clearly illustrate the thesis of the theory of chemical structure about the mutual influence of atoms in the molecules of substances.

The concepts of volatility and stability (stability) are often confused. Volatile acids are called acids, the molecules of which easily pass into a gaseous state, that is, they evaporate. For example, hydrochloric acid is a volatile but persistent, stable acid. The volatility of unstable acids cannot be judged. For example, non-volatile, insoluble silicic acid decomposes into water and SiO 2 . Aqueous solutions of hydrochloric, nitric, sulfuric, phosphoric and a number of other acids are colorless. An aqueous solution of chromic acid H 2 CrO 4 is yellow, permanganic acid HMnO 4 is raspberry.

Reference material for passing the test:

periodic table

Solubility table

Amphoteric metals are represented by non-complex elements, which are a kind of analogue of a group of metallic-type components. The similarity can be traced in a number of properties of the physical and chemical direction. Moreover, for the substances themselves, no ability to properties of the amphoteric type was noticed, and various compounds are quite capable of their manifestation.

For example, consider hydroxides with oxides. They clearly have a dual chemical nature. It is expressed in the fact that, depending on the conditions, the above compounds may have the properties of either alkalis or acids. The concept of amphotericity appeared quite a long time ago; it has been familiar to science since 1814. The term "amphoteric" expressed the ability of a chemical substance to behave in a certain way when carrying out an acidic (main) reaction. The properties obtained depend on the type of reagents themselves present, the type of solvent, and the conditions under which the reaction is carried out.

What are amphoteric metals?

The list of amphoteric metals includes many items. Some of them can be safely called amphoteric, some - presumably, others - conditionally. If we consider the issue on a large scale, then for brevity we can simply name the serial numbers of the above metals. These numbers are: 4.13, from 22 to 32, from 40 to 51, from 72 to 84, from 104 to 109. But there are metals that have the right to be called basic. These include chromium, iron, aluminum and zinc. Complement the main group of strontium and beryllium. The most common of all listed at the moment is aluminum. It is its alloys that have been used for many centuries in a wide variety of fields and applications. The metal has excellent anti-corrosion resistance, is easy to cast and various types of machining. In addition, the popularity of aluminum is complemented by such advantages as high thermal conductivity and good electrical conductivity.

Aluminum is an amphoteric metal, which tends to exhibit chemical activity. The resistance of this metal is determined by a strong oxide film and, under normal environmental conditions, during chemical reactions, aluminum acts as a reducing element. Such an amphoteric substance is able to interact with oxygen in the case of fragmentation of the metal into small particles. Such an interaction requires the influence of a high temperature regime. A chemical reaction in contact with an oxygen mass is accompanied by a huge release of thermal energy. At temperatures above 200 degrees, the interaction of reactions when combined with a substance such as sulfur forms aluminum sulfide. Amphoteric aluminum is not able to directly interact with hydrogen, and when this metal is mixed with other metal components, various alloys are formed containing compounds of the intermetallic type.

Iron is an amphoteric metal, which is one of the side subgroups of group 4 of the period in the system of chemical type elements. This element stands out as the most common component of the group of metallic substances, as part of the components of the earth's crust. Iron is classified as a simple substance, among the distinctive properties of which one can distinguish its malleability, silvery-white color scheme. Such a metal has the ability to provoke the occurrence of an increased chemical reaction and quickly passes into the stage of corrosion when exposed to high temperatures. Iron placed in pure oxygen completely burns out, and brought to a finely dispersed state, it can spontaneously ignite in plain air. Being exposed to air, a metallic substance quickly oxidizes due to excessive moisture, that is, it rusts. When burning in an oxygen mass, a kind of scale is formed, which is called iron oxide.

Basic properties of amphoteric metals

The properties of amphoteric metals are the basic concept in amphotericity. Let's consider what they are. In its standard state, every metal is a solid. Therefore, they are considered to be weak electrolytes. In addition, no metal can dissolve in water. Bases are obtained by a special reaction. During this reaction, the metal salt combines with a small dose of alkali. The rules require that the whole process be carried out carefully, carefully and rather slowly.

When amphoteric substances are combined with acid oxides or acids directly, the former give out a reaction characteristic of bases. If such bases are combined with bases, the properties of acids are manifested. Strong heating of amphoteric hydroxides leads to their decomposition. As a result of decomposition, water and the corresponding amphoteric oxide are formed. As can be seen from the examples cited, the properties are quite extensive and require careful analysis, which can be carried out in the course of chemical reactions.

The chemical properties of amphoteric metals can be compared with those of ordinary metals to draw a parallel or see a difference. All metals have a sufficiently low ionization potential, due to which they act as reducing agents in chemical reactions. It should also be noted that the electronegativity of non-metals is higher than that of metals.

Amphoteric metals exhibit both reducing and oxidizing properties. But at the same time, amphoteric metals have compounds characterized by a negative oxidation state. All metals have the ability to form basic hydroxides and oxides. Depending on the growth of the serial number in the periodic range, a decrease in the basicity of the metal was noticed. It should also be noted that metals, for the most part, can only be oxidized by certain acids. So, the interaction with nitric acid in metals occurs in different ways.

Amphoteric non-metals, which are simple substances, have a clear difference in their structure and individual characteristics with respect to physical and chemical manifestations. The type of some of these substances is easy to determine visually. For example, copper is a simple amphoteric metal, while bromine is classified as a non-metal.

In order not to be mistaken in determining the variety of simple substances, it is necessary to clearly know all the signs that distinguish metals from non-metals. The main difference between metals and non-metals is the ability of the former to give away electrons located in the external energy sector. Non-metals, on the contrary, attract electrons to the zone of external energy storage. All metals have the ability to transmit energy brilliance, which makes them good conductors of thermal and electrical energy, and non-metals cannot be used as a conductor of electricity and heat.

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Amphoteric metals chemical properties. amphoteric metals

Examples

see also

See what "Amphoteric oxides" are in other dictionaries:

What are amphoteric metals