Elements B. periodic system Mendeleev is divided into S-, P-, D-elements. This unit is carried out on the basis of how many levels there is an electronic shell of an element atom and how the filling of the shell is completed.

TO s-elementsinclude elements IA groups - alkali metals. Electronic formula for valence shell of alkali metal atoms nS1. Stable degree of oxidation is +1. Elements IA-bandhave similar properties due to the similar structure of the electronic shell. With an increase in the radius in the Li-FR group, the binding of the valence electron with the core weakens and the ionization energy decreases. Alkaline elements atoms easily give their valence electron, which characterize them as strong reducing agents.

Recovery properties are enhanced with an increase in the sequence number.

TO p-elementsinclude 30 elements IIIA-VIIIA groupperiodic system; P-elements are located in the second and third small periods, as well as in the fourth sixth large periods. Elements IIII-bandhave one electron on P-orbital. IN IVA-VIIIA-groupsthere is a filling of p-sud to 6 electrons. General electronic formula P-elements nS2NP6.. In periods, with an increase in the charge of the kernel, atomic radii and ion radii of p-elements decrease, the energy of ionization and the gear affinity increases, electronegativity increases, the oxidative activity of the compounds and the non-metallic properties of the elements are enhanced. In groups, the radii atoms increase. From 2p elements to 6P elements, ionization energy decreases. The metal properties of the p-element in the group with an increase in the sequence number are enhanced.

TO d-elementsinclude 32 elements of the periodic system IV-VII of large periods. IN IIIB-groupatoms, the first electron appears on the D-orbital, in subsequent B-groups, the D-sublayer is filled to 10 electrons. General formula for external electronic shell (n - 1) DANSB, where a \u003d 1? 10, b \u003d 1? 2. With an increase in the ordinal N, the D-elements are changed slightly. D-elements slowly occurs in an increase in the atomic radius, they also have a variable valence associated with the incompleteness of the antisomine D-electron. Advanced. In the lower degrees of oxidation, D-elements are detected by metal. SV-Wa, with increasing order. N In groups B, they decrease. In solutions, D-elements with the highest degree of oxide. Washing acid and oxidizes. CA, with lower degrees of oxidation - on the contrary. Elements from Paris. step. Oxidations show amphotern. CA.

Covalent connection.

Chem.Svyaz, carried out by common electron. Farams arising in the shells of associated atoms having anti-parallel backs, is called atomic, or covalent bond.Covalent. Communication two-electron and two centers (kept kernel). Atom at the external energy level is able to contain from one to eight electrons. Valence electrons- Electrons of the antislest, external electronic layers involved in chemical bond. Valence- property of the atoms of the element to form a chemical bond.

Elements in the periodic Mendeleev system are divided into S-, P-, D-elements. This unit is carried out on the basis of how many levels there is an electronic shell of an element atom and how the filling of the shell is completed.

TO s-elementsinclude elements IA groups - alkali metals. Electronic formula for valence shell of alkali metal atoms nS1. Stable degree of oxidation is +1. Elements IA-bandhave similar properties due to the similar structure of the electronic shell. With an increase in the radius in the Li-FR group, the binding of the valence electron with the core weakens and the ionization energy decreases. Alkaline elements atoms easily give their valence electron, which characterize them as strong reducing agents.

Recovery properties are enhanced with an increase in the sequence number.

TO p-elementsinclude 30 elements IIIA-VIIIA groupperiodic system; P-elements are located in the second and third small periods, as well as in the fourth sixth large periods. Elements IIII-bandhave one electron on P-orbital. IN IVA-VIIIA-groupsthere is a filling of p-sud to 6 electrons. General electronic formula P-elements nS2NP6.. In periods, with an increase in the charge of the kernel, atomic radii and ion radii of p-elements decrease, the energy of ionization and the gear affinity increases, electronegativity increases, the oxidative activity of the compounds and the non-metallic properties of the elements are enhanced. In groups, the radii atoms increase. From 2p elements to 6P elements, ionization energy decreases. The metal properties of the p-element in the group with an increase in the sequence number are enhanced.

TO d-elementsinclude 32 elements of the periodic system IV-VII of large periods. IN IIIB-groupatoms, the first electron appears on the D-orbital, in subsequent B-groups, the D-sublayer is filled to 10 electrons. General formula for external electronic shell (n - 1) DANSB, where a \u003d 1? 10, b \u003d 1? 2. With the increase in the sequence number, the properties of the D-elements change slightly. D-elegments slowly occurs increases atomic radius, they also have a variable valence associated with the incompleteness of the antisomine D-electronic sublevel. In the lower degrees of oxidation, the D-elements are detected by metal properties, with an increase in the sequence number in groups B, they decrease. In solutions, D-elements with the highest degree of oxidation detect acidic and oxidative properties, with lower degrees of oxidation - on the contrary. Elements with an intermediate degree of oxidation exhibit amphoteric properties.

8. Covalent bond. Method of valence ties

Chemical bond carried out by general electronic pairs arising in the shells of associated atoms having anti-parallel backs is called atomic, or covalent bond.The covalent bond is two-electron and double centers (kept kernel). It is formed by atoms of one species - covalent notolar- a new electron pair that arose of two unpaired electrons becomes common to two chlorine atoms; and atoms of various types similar to chemical character - covalent polar.Elements with greater electronegitability (CL) will delay the overall electrons from elements with less electronegitability (H). Atoms with unpaired electrons having parallel backs, repel - chemical communications Does not arise. The method of forming a covalent connection is called exchange mechanism.

Covalent bond properties. Communication Length -interstitial distance. What is the distance in short, the stronger chemical bond. Communication Energy -the amount of energy requested to break the bond. The magnitude of the multiplicity of communication is directly proportional to the energy of communication and inversely proportional to the length of communication. Focusing -certain location of electronic clouds in the molecule. Saturability- the ability of an atom to form a certain amount of covalent bonds. Chemical bond formed by overlapping electronic clouds along the axis connecting atom centers is called ? -Celusion.Communication formed by overlapping electronic clouds perpendicular to the axis connecting atom centers is called ? -Celusive. The spatial focus of the covalent bond is characterized by angles between connections. These corners are called valence angles. Hybridization -the process of restructuring is unequal in the form and energy of electronic clouds leading to the formation of the same parameters of hybrid clouds. Valence- number of chemical ties (covalent ), by which the atom is connected to others. Electrons involved in the formation of chemical bonds are called valentines. The number of connections between atoms is equal to the number of its unpaired electrons involved in the formation of common electronic pairs, therefore valence does not take into account the polarity and does not have a sign. In the compounds in which there is no covalent bond, there is degree of oxidation -the conditional atom charge, the original suggestion that it consists of positively or negatively charged ions. The concept of oxidation is applicable to most inorganic compounds.

Send your good work in the knowledge base is simple. Use the form below

Students, graduate students, young scientists who use the knowledge base in their studies and work will be very grateful to you.

Posted on http://www.allbest.ru/

1. general characteristics R-Elements of the Group III

The electronic configuration of the basic state in these elements NS 1 NP 2 is characterized by the presence of one unpaired electron. In the excited state, they contain three unpaired electrons, which, while in SP 2-hybridization, are involved in the formation of three covalent bonds. At the same time, atoms of elements of the IIIA group remains one unemployed orbital, and the number of valence electrons remains less than the number of orbitals available on the energy. Therefore, many covalent compounds of elements of group III are Lewis acids - an electron pair acceptors, by purchasing which, they not only increase the coordination number to four, but also change their geometry of their environment - one of the planes becomes a tetrahedral (state of SP 2-hybridization).

Bor differs in properties from other elements of this subgroup. Bor is the only nonmetall, chemically inert and forms covalent bonds B? F, b? N, b? C, etc., the multiplicity of which is often raised due to the RR? PP - binding. Chemistry Bora is close to silicon chemistry, the diagonal similarity is manifested in this. Aluminum atoms appear vacant D-orbitals, the radius of the atom increases, therefore it increases the diagnus number up to six. Gallium, India, tall lines are located immediately at the metals of the D-block; The filling of the D-shell is accompanied by a consistent compression of atoms. As a result of D-compression, the ionic radii of aluminum and gallium is close, and the atomic radius of gallium is even less. When moving from Al to Ga, the growth of the efficient charge of the kernel is more significant than the change in the atom radius, so the ionization energy increases. The growth of ionization energies during the transition from the II to Tl is the result of a D- and F compression, leading to an increase in the interaction of valence electrons with an atom core. Increased communication energy 6S 2 -Electrons Talloli with a kernel makes them involved in the formation of bonds and leads to a decrease in the stability of their compounds in the highest oxidation. So for talla, lead, bismuth and polonium is stable connections with oxidation degree +1, +2, +3, +

The p-elements of the III group include typical elements - boron and aluminum and elements of the subgroup of Gallium - Gallium, India, Tallium. All listed elements except boron are metals. All elements are rare, with the exception of aluminum, which accounts for 8.8% of the mass of the earth's crust. At the external electron level, they have three electrons NS 2 NP 1, and in the excited state - NS 1 NP 2 electrons. The highest degree of oxidation of the elements of the subgroup of Bora is +3. Due to the fact that in the atoms Ga, In, T1, the penultimate level contains 18 electrons, the patterns of certain properties during the transition from A1 to GA are disturbed. Some physical constants of the elements of the subgroup of IIII are given in Table. 7.

2. Elements of group IIII (subgroup of boron)

2.1 boron

Natural resources . In the free state of Bohr does not occur, but only in the associated state. Main minerals - borates: Na 2 B 4 0 7 10N 2 O - Bura, H 3 at 3 - Boric acid, Bora Bor nitride.

Getting. The technical (amorphous) boron is obtained by the magnic termic restoration of its oxide:

3MG + B 2 O 3 3MGO + 2B; N.<0.

MgO is removed by dissolving in HCl. The crystal boron is obtained by the reduction of hydrogen halides:

2VR 3 + ZN 2 6HBR + 2B.

Properties. Bor is known in amorphous (brown) and crystalline (black) forms. The crystal grille of the boron is very durable (Ikosahedra), it is manifested in high hardness, small entropy S 0 (B) \u003d 7 e.e. and high melting point. Bor - semiconductor, the width of the forbidden zone is 1.42 eV.

Bor - First P is an element in a periodic system of elements. The structure of the outer electronic shell 2s 2 2p l. The excitation translates the atom in SP 2 - the hybrid valence state in which the orbital is located under 120 0 (BFZ, BP1Z). Due to the presence of free p-orbital and the small size of the atom, the boron is one of the strongest acceptors of vulnerable electronic pairs, forms complex ions like:

Bf 3 (g) + hf \u003d h (p),

BF 3 (g) + F - (p) \u003d -1 (P).

The complex ion [BF 4] -1 has a tetrahedral structure, which is also characteristic of other boron compounds.

Properties of elements of subgroup III A

Properties of elements
Atomic radius, nm
Ion radius e 3+, nm
Ionization energy E 0 E +, EV
Melting point, ° С
Boiling temperature, ° С
Density, g / cm 3
E 0 (e 3+ / e 0), in
Electricity
Degree of oxidation

With donor-acceptor interaction, the presence of a large number of inorganic boron-containing polymers is connected. By the meaning of electronencestability, the boron is almost in the middle of the electronegability scale, so it can be as an oxidizing agent in compounds with an oxidation degree of +3 (BF 3, in 2 O 3) and the reducing agent in compounds with the degree of oxidation -3 (Mg 3 B 2, In 3 H 6). Communications formed by boron are covalent. The boron is typical of the compounds in which it includes the composition of the complex anion (in 4 o 7 2-, BF 4 -).

Bor detects a diagonal analogy with silicon. For boron and silicon are most characteristic of the derivatives in which these elements are polarized positively. For both elements, their lower hydrides are small-resistant and gaseous. Many general has chemistry of oxygen compounds of boron and silicon: the acidic nature of oxides and hydroxides, glass formation of oxides, the ability to form numerous polymer structures, etc. Under normal conditions, Bor is chemically inert. Water does not work on Bor; Concentrated nitric and sulfuric acids oxidize it to boric acid:

2B + zn 2 s0 4 \u003d 2n 3 of 3 + 3SO 2,

B + 3HNO 3 \u003d H 3 is 3 + zn0 2.

Boiling salt and float acid do not work on it. The amorphous boron is dissolved in concentrated solutions by alkalis with the formation of metablasts:

2B + 2C 2N 2 O 2KVO 2 + ZN 2.

In all cases, the crystalline bor is chemically less active than amorphous. In chemical reactions, Bohr often acts as a reducing agent.

Bora hydrogen compounds. With hydrogen boron does not react; Borochifers or borants are obtained by artificially. These are gases or volatile fluids with an unpleasant smell, very poisonless! They can be divided into two groups: b n h n +4 (B 2 H 6) and b n h n +6 (B 4 H 10). Boran PMZ exists as an intermediate product in chemical reactions whose particles, interacting with each other forming a dimer (dibran):

2bh 3 (g) \u003d b 2 H 6 (g), G 0 \u003d -126kj

Dibers get:

1) ZNA [VN 4] + 4BF 3 Gas phase 2B 2 H 6 + ZNA [BF 4];

2) 2vs? Z + 6h 2 (g) gas phase in 2 H 6 + 6ns1;

These reactions occur in the gas phase or in non-aqueous media.

Moboran is an energetic reducing agent; flammped in air:

In 2 H 6 + 3o 2 3N 2 O + in 2 O 3;

energetically interacts with water with hydrogen release:

In 2 H b + 6n 2 0 2B (it) 3 + 6N 2.

In the 2 n-b ether medium, it reacts with lithium hydride, forming lithium tetrahydrobraths:

In 2 H 6 + 2LIN 2Li.

With oxygen BOR forms oxide in 2 o 3 - white hygroscopic powder or fragile vitreous mass. B 2 O 3 energetically attach water, forming acids:

B 2 O 3 + H 2 O \u003d 2HBO 2 (Metal Acid),

HBO 2 + H 2 O \u003d H 3 BO 3 (Ortoboric Acid).

Ortoborny (or simply boring) acid - white crystalline substance, easily rescurate on very thin pearl flakes. H 3 3 molecules, located in flat parallel layers, are bound by hydrogen bonds, and the connection between the layers is carried out by the weak forces of Van der Waals. Boric acid is well soluble in water, as well as in some solutions of organic solvents. In aqueous solutions, it manifests itself as a monosular acid, due to the formation of hydroxcomplexes:

In (it) 3 + H 2 0 \u003d H [B (OH) 4].

Hydrogen tetrahydrokvorate is a weak acid close by power to coalic acid. Ortoboric acid H 3 at 3 at 100 ° C with the cleavage of the water molecule goes into the HBO 2 metamic acid. And orthoborates, and active metals are subjected to hydrolysis:

Na 2 B 4 0 7 + ZH 2 O2NAB0 2 + 2H 3 BO 3.

Acid H 2 B 4 o 7 in a free state of unknown, its tetraborate salts are found in nature; Sodium tetrabrate is formed by neutralizing H 3 BO 3 with aqueous alkalis solutions:

4H 3 of 3 + 2None \u003d Na 2 in 4 o 7 + 7n 2 O.

The degree of oxidation is +3 in boron manifests itself in compounds with more electronegative elements (nitrides, halides).

The acid nature of halides is manifested when their hydrolysis:

Sun1 3 + zn 2 o \u003d H 3 of 3 + ZNS1.

With nitrogen Boron forms the BN connection - boron nitride. Synthesis is carried out at temperatures above 1200 ° C by reaction:

B 2 O 3 + 2NH 3 \u003d 2BN + 3H 2 O.

The boron nitride thus obtained is a white, powder similar to talc; It is often referred to as "white graphite". Its crystal structure is similar to graphite. Boron and nitrogen atoms are interconnected by SP 2 - hybrid connections. The plane of the layers is carried out additional - binding due to the empty p - orbital of the boron atom and the vicious electronic pair of the nitrogen atom. Separate layers are connected by Van der Waals. "White graphite" has high refractority, chemically inert and is stratified on scales as graphite.

Another modification of boron nitride has a cubic diamond-like structure. In it, boron and nitrogen atoms are in SP 3 - hybrid state. With QC \u003d 4, three bonds are formed by the exchange mechanism, and one by donor-acceptor, and the boron atom is an electronic pair acceptor, and a nitrogen atom is a donor. This modification of BN is called burezone or elbor. At high temperatures, elbor can be obtained from "white graphite", just as the diamond is obtained from black graphite:

BN (Hex) BN (Cube).

When heated with carbon, the boron forms carbide in 4 s:

7C + 2V 2 O 3 6CO + in 4 C.

Bora carbide is inferior on hardness only with diamond and boron.

When heated, BOR interacts with many metals, forming borides of various composition, for example: SG 4 V, SG 3 V, SGV, SGV 2. These are crystalline substances. All borides of D-elements are characterized by a large hardness, refractory and chemically inert. Borides S - elements, for example, MGB 2, reactive.

Application. Bohr is used as an additive to alloys, increasing their heat resistance and wear resistance. Since the boron kernel has a high cross section of neutron capture, boron is used to protect against neutrons and in adjusting devices of atomic reactors.

Borates are part of many detergents. In 2 o 3 - the necessary part of the row of enamels, glaze and special varieties of glass. In the microelectronics, the boron is used as a semiconductor, it is used to doping semiconductor materials. White graphite serves as an insulator and solid high-temperature lubricant. Baranon is used as an overall material in drilling work, when processing metals. Borides are used for the manufacture of highly impact details.

Boric acid is used in medicine. Sodium Tetrabrate NA 2 in 4 0 7 (Bura) is used as a flux when soldering, because In the melt of this salt, metal oxides are well dissolved with the formation of metablasts:

Na 2 B 4 O 7 + CuO2NabO2 Cu (BO 2) 2.

2.2 Aluminum

The second typical element III of the periodic system. Aluminum is the first and easiest p-metal. Aluminum compared to the boron atomic radius is greater, and the potential of ionization is less; Consequently, its metal properties increase. Unlike non-metallol, aluminum boron is an amphoteric element. Aluminum and its hydroxide dissolve in acids and alkalis. For chemistry of aluminum, its great oxygen affinity is extremely important, in Table 8 shows the values \u200b\u200bof the enthalpy and energy of Gibbs formation of aluminum oxides and its analogues.

Thermodynamic parameters of group IIIs

And enthalpy, and the Gibbs Energy of Aluminum Education differ sharply from those for Gallium and its analogues, which indicates its high stability. And finally, a horizontal analogy with silicon is observed for aluminum. It is clearly manifested in aluminosilicates most common in earth Kore Chemical compounds.

Natural resources . Aluminum is one of the most common elements on Earth, ranks third in the prevalence after oxygen and silicon. Aluminum is part of 250 minerals, mainly aluminosilicates, of which the earth's crust is formed; The product of their destruction is clay A1 2 O 3 2SIO 2 2N 2 O (kaolinitis). Usually clay contains an admixture of iron compounds that gives it a brown color. Sometimes there is a white clay, without glaze impurities. Technical name A1 2 O 3 - alumina. Minerals are used for aluminum mining: Bauxite A1 2 O 3 H 2 O, as well as Na 2 Oal 2 O 3 2Sio 2, Cryolith Na 3. Clean A1 2 O 3 - Corundum. Depending on the content of impurities, Corundum has a different color and name. Precious stones Ruby and sapphire are Corundum crystals painted by admixture of chromium oxide (ruby) and titanium and iron oxides (sapphire).

Aluminum is obtained by the electrolysis of the melt of the mixture of alumina with cryolite. Melt a? 2 O 3 in cryolate Na 3 is subjected to electrolysis at 950 ° C and voltage of 6-7 B. Processes flowing:

Al 2 O 3 \u003d 2a? 3+ + 3O 2 - (dissociation per ions);

at the cathode: a? 3+ + 3e \u003d a?;

on the anode: 2O 2- - 4E \u003d O 2.

Particularly pure aluminum, necessary, for example, in electronic technology, is obtained by special methods: vacuum distillation or zone melting.

Physical and chemical properties of aluminum . Aluminum - silver-white metal. Very soft, easily stretched into foil. Crystallizes in the ICC - structure. Electric conductivity ranks fourth after silver, gold and copper. On the air is covered with the finest film (10 -5 mm) Al 2 O 3, characterized by great strength. The protective film reliably protects the metal from further oxidation. Almost all reactions involving aluminum go with a latent (hidden) period necessary to destroy the oxide film or the diffusion of the reagent through it.

With pnikogens and chalcoops, aluminum interacts at high temperatures. With halogens, with the exception of iodine, aluminum does not directly react. Concentrated sulfur and nitric acids pass it, so it does not dissolve in them. Aluminum is dissolved in hydrochloric acid and in alkalis solutions:

2a? + 6ns? \u003d 2a? C1 3 + zn 2,

2a? + 2NAOH + 6H 2 O \u003d 2NA + 3H 2..

Aluminum devoid of protective film, vigorously interacts with water:

2a? + 6N 2 O \u003d 2a? (OH) 3 + 3H 2.

Chemical bond in aluminum compounds has a greater fraction of ionicity than in boron compounds. So, B 3 -gaz, ah? F 3-hard compound with a high melting point, it is quite possible to name salt; Haloenides Ah? C1 3, ah? Vg 3, ah? i 3 detect properties, intermediate between the properties of non-metallic halides and salts.

Ion a? 3+, having a small radius and a large charge, shows a tendency to complexation, and aluminum it is greater than in magnesium, and less than at the boron. Aluminum forms strong complexes with H 2 O, OH -, F -; Like all S- and P - elements do not give durable complexes with ammonia and its derivatives. During complexation in chemical communication, free D - orbital aluminum atom may contribute. This explains the possibility of formation of complexes with K.ch. \u003d 6, for example, [Ah? (H 2 O) 6] 3+ (SP 3 D 2 - hybridization).

Connections. Aluminum does not react with hydrogen. Aluminum hydride is obtained indirectly by acting a lithium hydride in an ethereal solution at A1C1 3:

A? C? 3 + 3lih a? H 3 + 3Lic?.

Aluminum hydride Aln 3 - white powder; This is a polymeric compound (A1N 3) N. If the previous reaction is carried out with an excess LIH, we get lithium tetrahydroaluminda:

A? C? 3 + 4Lihli + 3hc?.

Li strong reducing agent, reacts violently with water with hydrogen release:

Li + 4h 2 olioh + a? (OH) 3 + 4H 2.

When heated, aluminum is vigorously interacting with oxygen:

4a? (d) + 3O 2 (g) \u003d 2a? 2 O 3 (k); G ° \u003d -3164 kj.

Aluminum Oxide AL 2 O 3 - Very solid, refractory, chemically resistant compound (T pl \u003d 2072 O C, T KIP \u003d Z500 O C), is destroyed only with long-term heating with acids or alkalis:

BUT? 2 o 3 + 6ns? \u003d 2a? C? 3 + zn 2 o,

A? 2 O 3 + 2NAOH \u003d 2NAA1O 2 + H 2 O.

In alkaline solutions, hydroxyalulums are formed:

A? 2 O 3 + 2NAOH + 7H 2 O \u003d 2NA.

Hydroxide aluminum ah? (OH) 3 amphoteric compound, it corresponds to two types of salts: aluminum salts (III), for example, a? 2 (SO 4) 3, and? S? 3, and aluminates - salts of aluminum acids. In aqueous solutions, the aluminates exist in the form of hydroxamplexes, for example, to [e? (OH) 4], in melts in the form of coles non-existent in the free state of metaaluminic acid, for example, ka? O 2. The equilibrium scheme in a saturated aqueous solution A1 (OH) 3 can be represented as follows:

A? 3+ + 3Oh? A? (OH) 3 H H + + -

solving solution

The addition of acid (H +) leads to an equilibrium displacement towards the formation of Al 3+ cation (aluminum salts of cationic type):

BUT? (Oh) 3 + zn + \u003d a? 3+ + ZH 2 O.

Adding alkali (it is) - towards the formation of anions (salts of anion type aluminum):

BUT? (He) 3 + he - \u003d -.

Aluminum salts in aqueous solutions are strongly hydrolyzed. The reaction of the medium depends on the type of dissolved salt:

A? 3+ + H 2 OA? OH 2+ + H + pH< 7.

Soloi ah? 3+ and weak acids are hydrolyzed completely with the formation of precipitation of aluminum hydroxide or aluminum hydroxases:

A? (CH 3 SOO) 3 + 2N 2 OA? ON (CH 3 Soo) 2 ++ Ah? (He) 2 CH 3 Soo + CH 3 Soam.

Due to strong hydrolysis, many aluminum salts cannot be isolated from aqueous solutions (for example, sulfide, carbonate, cyanide, etc.):

BUT? 2 S 3 + 6H 2 O \u003d 2a? (OH) 3 V + 3H 2 S ^

Aluminum salts and oxygen-containing acids are soluble in water. Exception is an aluminum phosphate A? RO formation of a low-soluble phosphate playing important role in the vital activity of organisms. The absorption of phosphorus organism decreases in the presence of cations ah? 3+ due to the formation of low-soluble phosphatyluminia in the intestines. This circumstance must be taken into account when appointing aluminum drugs, for example, the means against the increased acidity of the stomach Ah? (OH) 3.

In the stomach, aluminum hydroxide forms a gel that neutralizes the ions of the gastric juice hydroxion:

A? (OH) 3 + 3N 3 o + \u003d a? 3+ + 6N 2 o

The aluminum aluminum ions passed into the solution are transferred to a poorly soluble form - aluminum phosphate:

A? 3+ (P) + PO 4 3- (p) \u003d a? Po 4 (t)

In living organisms with biolygandas (oxyc acids, polyphenols, carbohydrates, lipids), aluminum forms chelate complex compounds. As a rule, communications with organic ligands, it forms through oxygen atoms.

In dental practice, are widely used by aluminum compound, for example, white clay (kaolin) a? 2 O 3 SiO 2 2H 2 O. Kaolin is part of cements that are used as temporary sealing material, as well as for stamping crowns.

With metal sulfates in the degree of oxidation +1 aluminum sulfate forms dual salts of the type 2 SO 4 e? 2 (SO 4) 3 12N 2 O. These compounds were called aluminum alum. The alum in solid state is stable, and in solutions are dissociated to the components of the ions. Alums are well soluble in water and crystallized from solutions, forming large octahedral crystals.

Aluminum hydroxide is obtained in the form of amorphous precipitation. Crystal A? (OH) 3 can be obtained by passing CO 2 through alkaline solutions of sodium aluminate:

2 Na + 2CO 2 \u003d 2a? (OH) 3 V + 2NAHCO 3 + 4H 2 O

Application. Aluminum - the second (after iron) metal in terms of production and application in the technique. Used both pure aluminum and its alloys. The alloy is duralumin containing 4% (mass.) Cu, 1.5% Mg, 0.5% Mn is the main construction material in aircraft industry. A large amount of aluminum goes to the manufacture of wires. The first artificial satellite of the Earth was made of aluminum alloys. Due to the high affinity with aluminum oxygen, the method of altertermia is possible - the separation of metals from their oxides under the action of aluminum. Alummithium is used for laboratory production of many metals (Mn, Cr, V, W, etc.), in some cases in industry (obtaining SR, BA, etc.)

From aluminum oxide, refractory and chemically resistant ceramics are made. In large quantities, the single crystals are purified or? 2 O 3 with additives of impurities (artificial rubies and sapphires). Of these, lasers and bearings are made for accurate mechanisms.

Aluminum compounds are part of many silicate industry products (cement, porcelain, ceramics). The alum is used in the leather and in the textile industry. Aluminum sulfate is used for water purification. The first stage of the water purification is based on the reaction:

BUT? 2 (SO 4) 3 + ZSA (NSO 3) 2 zso 4 + 2a? (OH) 3 + 6CO 2.

The formed aluminum hydroxide flakes are fascinated by various impurities. Aluminum chloride and lithium hydroallyumat are used in organic synthesis.

From aluminum salts crystalline medical practice Find the use of alumocalya ka? (SO 4) 2 12H 2 O and burned ka? (SO 4) 2, which are obtained by heating alumokalia alum at a temperature not higher than 433 K.

Luggage alums are used as an astringent and drying agent. The drying effect is due to the fact that the burning alum slowly absorb water:

Ka? (SO 4) 2 + xh 2 o \u003d ka? (SO 4) 2 xh 2 o

The pharmacological effect of aluminum salts is based on the fact that ions a? 3+ form with proteins (Proteins PR) complexes falling in the form of gels:

A? 3+ + PR\u003e A? PR

This leads to the death of microbial cells and reduces the inflammatory response.

Alums are used for rinsing, washes and rings in inflammatory diseases of the mucous membranes and skin. In addition, this drug is used as a hemostatic remedy for cuts (coagulation).

2.3 Gluff subgroup

Despite the fact that elements of the Gallium subgroup are typical analogs, features are observed in the properties of its individual representatives. Gallium directly follows the first tent of the transition 3D-metals, for which the D-contract is particularly strong, therefore the atomic radius of gallium is not only less than its heavier analogues, but also aluminum, as a result of this, other energy characteristics differ from its analogues.

Natural connections. Gallium, India, Tallium, unlike aluminum, rare and scattered elements. They enter as an impurity in various ores. There is almost one Gallium mineral - Cugas 2 Gallites, rarely found. Gallium accompanies aluminum and zinc. Individual ores Rochene Cuins 2 and Indies FEINS 2 are also very rare. The main raw materials for thallium are polymetallic ores.

Getting. Salts and oxides GA, IN, T? It is isolated by processing aluminum production and extracting the compounds of these metals from polymetallic ores. Free metals are obtained by electrolysis of acidified aqueous solutions from salts or restoration of their coal oxides or hydrogen. Selected metals are purified by zone melting or amalgam metallurgy methods.

Properties. The existence of Gallium - Ekalamnia was predicted by D.I. Mendeleev in 1870, as well as "calculated" the main properties of this element. In 1875, the French chemist leak de Baabodran opened and allocated this element. In the free state of gallium, indium, thallium - silver-white metals. Galya fragile, and India and Tallium are very soft metals. Gallium and indium in air is stable, in contrast to thallium, which in a wet atmosphere is covered with a layer of hydroxide and quickly destroys. The crystal gallium grill is unique among metals, consisting of atomic pairs Ga 2, causes the unusual properties of metal gallium. For it, a low melting point is characterized, a smaller density of crystals compared to liquid, a large tendency to supercooling. Gallium is a substance with a very large temperature range of the existence of the liquid phase. In pairs gallium monatomotane.

Gallium, India, Tallal - chemically active. In relation to different oxidizers, they show individual characteristics. Gallium reminds aluminum (especially in relation to alkalis); In HNO 3 dissolves slowly, it is well dissolved in NS1 and H 2 SO 4; Tallium is well soluble in HNO 3:

T? + 4hno 3 \u003d t? (NO 3) 3 + NO + 2H 2 O,

and in ns1 and n 2 SO 4 slowly due to passivating films t? C? and t? 2 SO when dissolved in gallium and indium acids behave like trivalent metals, and thallium forms Ti + salts; Because ion TL 3+ Unstable:

2Ga + 6hc? \u003d 2Gac? 3 + 3H 2, ^

2t? + 2ns? \u003d 2t? S? + H 2 ^

Gallium and Indium interacts with alkalis with the formation of gallates and indents with hydrogen release, and gallium reacts quickly, and India is slow.

2Ga + 6NAOH + 6H 2 O \u003d 2NA 3 + ZH 2.

With hydrogen gallium, indium and tall lies do not react. An indirect way can be obtained easily decomposing hydrides: Ga 2 H 6 (liquid) and GaN 3, Inn 3 (polymers similar to AIN 3). When heating gallium, indium and tall lines, oxides of the type 2 O 3 and the corresponding hydroxides of me (OH) 3 (Table 9) are formed.

Increasing the stability of low degrees of oxidation in a row of Ga-In-Ti shows the following pattern: GA 2 O 3 melts without decomposition, IP 2 O 3 decomposes when heated above 850 ° C, t? 2 o 3 begins to split oxygen at 90 ° C, turning into Ti 2 O.

With increasing atomic number The intensity of the color increases: Ga 2 O 3 - white, in 2 O 3 -Hell-yellow, t? 2 O 3 - brown. This fact indicates an increase in the fraction of ionicity in oxides with an increase in the atomic mass of the element. Ga 2 O 3 is isoostructured by Corundum, and in 2 O 3 and T? 2 O 3 crystalized in the type O.K. type lattice The interaction with alkalis in the specified row weakens: Ga 2 O 3 dissolves in alkali solutions well, forming hydroellos, t? 2 O 3 practically does not dissolve:

Ga 2 O 3 + 2NAOH + 3H 2 O \u003d 2NA.

In the melt alkalis, anhydrous gallates are formed:

Ga 2 O 3 + 2NAOH \u003d 2NAGAO 2 + H 2 O.

Na 3 hydroxointes are formed only with greater alkali excess. Under the action of water, Hals and Indates are completely hydrolyzed:

Nagao 2 + 2HOH \u003d NaOH + GA (OH) 3.

GA hydroxides (OH) 3, In (OH) 3, T? (OH) 3 are obtained by acting alkali solutions to the solutions of the corresponding salts. Gallium hydroxide dissolves in strong acids and bases. It is a rare example of an ideal ampholite, for which acidic and basic properties are expressed almost equally. For dehydration Ga (OH) 3, heating is required, and Ti (OH) 3 spontaneously loses water at room temperature, as evidenced by values \u200b\u200bG 0 298:

2Ga (OH) 3 (k) \u003d Ga 2 O 3 (k) + 3H 2 O (R); G 0 298 \u003d - 8 kJ,

2t? (OH) 3 (k) \u003d T? 2 O 3 (k) + 3H 2 O (R); G 0 298 \u003d -117 kJ.

Oxide t? 2 o 3 Unlike its analogues decomposes at 100 ° C: and oxidizes the NA? before s? 2: T? 2 o 3 + 6ns? \u003d 2t? S? + 3n 2 o + 2c? 2.

T? 2 O is obtained by direct metal oxidation in air with a slight heating. Ti 2 O - black powder; In the molten state - yellow, easily dissolved in water with alkali formation, that is, behaves like an alkali metal oxide. Ti 2 O melt destroys silicates - glass, porcelain. The same action also has a solution? Oh (strong alkali). Hydroxide T? It is obtained by the exchange reaction: Hydroxide Talloline (I) Pars the burglary gas:

2t? Oh + CO 2 \u003d T? 2 CO 3 + H 2 O

T? 2 CO 3 + CO 2 + H 2 O \u003d 2T? NSO 3

At room temperature Ga, In, T? React with halogens F 2, C? 2, BR 2, and when heated with i 2. As a result, the halides of EG 3 are formed. According to the properties of GAg 3 closer to nonmethel halides, and ing 3 and t? G 3 to the salts.

Many GA +3, In +3 salts are known? +3, most of them are well soluble in water. Ga 3+, in 3+ ions are colorless, t? 3+ has a light yellow color. All salts of the e 3+ metals under consideration are susceptible to hydrolysis. Chalcogenides are known for Gallium and India. For thallium is known sulphide t? 2 S 3, which can be obtained by dry path. Hydroxide T? OH is obtained by the exchange reaction:

T? SO 4 + BA (OH) 2 \u003d Baso 4 V + 2t? Oh

Application. Metal gallium and indium are used in vacuum techniques: Gallium for liquid-metal shutters (replacing mercury), as sealing pads in the devices where a high vacuum is created. Gallium can be used to make optical mirrors, characterized by high reflective ability.

A variety of applications have semiconductor materials of the elements of the Gallium subgroup (GaAs, Gasb, Inas, Insb, T1 2 S 3, etc.). These semiconductors work in the photocells and in photose prerequisites that perceive infrared radiation.

3 . Biological role of R-elementsIIIA-groups

Boron Bor refers to impurity microelements, its mass fraction in the human body is 10 -5%. Boron concentrates mainly in the lungs (0.34 mg), thyroid gland (0.30 mg), spleen (0.26 mg), liver, brain (0.22 mg), kidneys, heart muscle (0.21 mg) . The biological effect is not yet sufficiently studied. It is known that the boron is part of the teeth and bones, in the form of hard-soluble boric acid salts with metal cations.

Excess boron is harmful to the human body. It is evidence that the large excess boron is inhibited amylases, proteinases, reduces adrenaline activity. It is assumed that the decrease in the activity of adrenaline, which is polyphenol derivatives, is associated with its reaction with a disrupted acid.

It has long been known that Bor is needed by higher plants, but the data on its biological role is contradictory.

Studies conducted in last yearsshowed that Bor is necessary for some animals. It has been established that BOR is involved in carbon-phosphate exchange, interacts with a number of biologically active compounds (carbohydrates, enzymes, vitamins, hormones). At the same time, the use of foods with a large content of boron disrupts the body of carbohydrates and proteins in the body, which leads to the emergence of endemic intestinal diseases - enteritis.

Aluminum.By content in the human body (10 -5%), aluminum refers to impurity microelements6tes. Aluminum is concentrated mainly in serum, lungs, liver, bones, kidneys, nails, hair, enters the structure of the nerve shells of the human brain.

The daily consumption of aluminum by man is 47 mg. Aluminum affects the development of epithelial and connective tissues, on the regeneration of bone tissues, affects the exchange of phosphorus.

Aluminum has an action on enzymatic processes. In most cases, Cation A? 3+ replaces ions E 2+ - enzyme activators, for example, Mg 2+ ions, Ca 2+:

E 2+ E + A? 3+ \u003d e 2+ + a? 3+ E.

Such interchangeability is possible due to the similarities of a number of properties of ions a? 3+ and Mg 2+, Ca 2+. Excess aluminum in the body inhibits hemoglobin synthesis, since due to the rather high complex-forming ability of aluminum blocks the active centers of enzymes involved in blood formation. There is evidence that aluminum can catalyze the transamination reaction (transfer NH 2 -Groups.)

Gallium. Gallium is an impurity microelement (the content in the body of man 10-6 - 10- 5%). The biological role of halves in living organisms is almost not clarified.

Indium. Currently, the biological effect of India is unknown, there is no reliable information about its availability in living organisms. Given the proximity of the atomic structure and the physicochemical properties of India and Gallium, one can predict the similarities of their biological action. Obviously, India, like aluminum, falling into the body should accumulate in bone and other tissues in the form of a poorly soluble phosphate.

Thallium. Tallium refers to very toxic elements. TL + ion is inclined, like AG +, to form durable compounds with sulfur-containing ligands:

TL + + R - SH\u003e R - S - TL + H +

As a result, it is toxic, as it suppresses the activity of enzymes containing thiogroups - SH. Even very minor quantities of TL + compounds when hitting the body cause hair loss.

Due to the proximity of radii K + and TL + (? R \u003d 11 PM), they have similar properties and are able to replace each other in enzymes. TL + and K + ions are synergists. This explains the fact that the enzymes of piruvatkinase and dionhyrattasis are activated not only by ions to +, but TL + ions (ion Tl + replaces K + in the catalytic center of enzymes). Synergism Tallulia and Potassia manifests itself in that similar to ions K +, TL + ions accumulate in red blood cells.

As an antidote in poisoning, TL + ions use a sulfur-containing ligand - the amino acid of Cystin HS-CH 2 CH (NH 2) COOH.

In conclusion, it should be noted that the biological role of the R-elements of the IIIA-Group is not sufficiently studied. Currently, it is known that Bor and Gallium interact in plants with polyphenol inhibitors, reducing the toxicity of the latter. There is also an undoubted role of aluminum in the construction of epithelial and connective tissues, and in addition to its participation in enzymatic processes, both as an activator and as an inhibitor. The property inhibit many sulfur-containing enzymes is the TL + ion.

The biological activity of the R-elements of the IIIA group is mainly related to their ability to education. complex compounds with oxygen-containing ligands and insoluble phosphates.

4. Elements of the IVA group (carbon subgroup)

4 .1 General characteristics of the elements of the group IVA

The fourth main group of the periodic system includes two typical elements of carbon and silicon, and elements: Germanium, lead tin (subgroup of Germany). Carbon is the basis of organic chemistry, the main organogenic element, the necessary component of the organism of all living beings. The second typical element - silicon is the main element of inorganic chemistry and all inanimate nature. Silicon and Germanium - dominant semiconductor materials. The integrated schemes based on silicon and Germany are the basis of computers, microprocessors, etc.

All elements of this subgroup contain four valence electrons - this is NS 2 NP 2 electrons. This number of valence electrons is optimal for the occurrence of tetrahedral bonds on the exchange mechanism. Some physico-chemical constants of these elements of the subgroups are given in Table. 10.

Within iVA groups, the dependence of properties from the position of the element is observed. So, OEO Germany is more than silicon, although the first potential of ionization Germany is less. This is due to the existence of a Germany atom in contrast to silicon filled with internal 3D 10, which serves as a screen for P-electrons. In a series of C - Si - Ge - Sn - Pb, the ionization energy decreases and the atomic radius increases, that is, metal properties are enhanced. The first two elements are typical non-metals, silicon and germanium - semi-metals. Lead typical - metal. All elements exhibit the degree of oxidation: +4, +2, and, from top to bottom, stability high degree Oxidation decreases, but low increases. In compounds of elements with oxidation degree (+4), oxidative properties are enhanced from carbon to lead, and rehabilitation properties are weakened with compounds with oxidation degree (+2). For example, germanium and tin into the degree of oxidation (+2) are strong reducing agents, in compounds GE (+2) reducing properties are so strong that they are disproportionated in the absence of an oxidant. For lead, the degree of oxidation (+2) is the most stable, and PB compounds (+4) are strong oxidizers.

Properties of the elements of the carbon subgroup

Properties
Atomic radius, nm
Ion radius e -4, nm
Ion radius e +4, nm
Ionization potential I in
The width of the prohibited zone, eV	5.2 (diamond)
Melting point, 0 s
Boiling point, 0 s
Density, g / cm 3	3,51
E (e 3+ r-p / e), in
Degree of oxidation

4.2 Carbon and its connections

Natural resources. The carbon content of the earth's crust is 0.1%. It means both in free form (diamond, graphite), so in the associated condition (carbon dioxide, carbonates, oil, natural gas, shale oil, bitumen).

Depending on the number of U-bonds, the coordination number of carbon is equal to four (SP 3 - hybridization), three (SP 2 - hybridization), or two (SP - hybridization) of valence orbitals:

In accordance with the characteristic hybrid states of orbitals, carbon atoms can be combined into polymeric formations of coordination (SP 3), layered (SP 2) and linear (SP) structures.

This corresponds to three simple substances: diamond, graphite, carbines. In the condensation products of graphite steam highlighted a new carbon modification - fullerene.

Diamond(SP 3) - a crystalline substance with a atomic coordination grid, which has a large hardness and significant density. He is harder than all substances. It is widely used for cutting glasses, drilling rocks, polishing of particularly solid materials. Its samples in pure form strongly refract the light (glow). Diamonds receive diamonds with a special cut of transparent crystals. This is the most expensive precious stones. The mass of the diamond is expressed in carats (1 carat corresponds to 0.2 grams). The cost of the diamond increases in proportion to the square of its mass.

With SP 2 hybridization, a flat structure is formed graphite. Graphite is a black and gray crystalline substance with a weak metal glitter. The distance between the layers is very large (0.335 nm), and the intermolecular forces between layers in graphite are very small. Graphite splits into thin scales, which themselves are very durable and easily stick to paper. Graphite of refractory, it prepares crucible for metallurgy. IN nuclear reactors Graphite is used as a neutron retarder. It is found in the form of deposits (Altai), it turns out of coke. The transition of graphite in a diamond is carried out at a temperature of 1800 ° C and a pressure of 6 GPa in the presence of solvents (melted FES, TA, Ni, etc.).

With SP hybridization is formed karbinopened in 1963, later discovered in nature. Carbin is obtained by catalytic oxidation of acetylene. CARBIN - fine-crystalline black powder. Crystals of carbine consist of linear chains of carbon atoms connected by alternating single and triple connections:

- with C - with C - ... (- with C -) N

The hardness of carbines is superior to graphite, but is inferior to diamond. It has semiconductor properties. When heated (T \u003d 2880 ° C), without access, the air turns into graphite.

The varieties of graphite include soot and charcoal. Coal is obtained with thermal decomposition of carbon compounds. Coal is finely crushed graphite. Charcoal is obtained when charging wood. Coal (especially woody) contains a large number of pores, therefore it has a large adsorption capacity. Adsorption is called the property of coal and other solid bodies to hold on its surface pair, gases and solutes. Substances on the surface of which adsorption occurs, are called adsorbents. If you skip through the ink dried coal (coal - adsorbent, ink - adsorbat), then they are discolored. In the technique, aluminosilicates are used as adsorbents. In medicine, the tablets from activated carbon are used to remove harmful substances.

Chemical properties. At normal temperature, the carbon is very inert, under certain conditions there is oxidative and rehabilitation properties. Oxidative properties are manifested in reactions:

4a1 + 3 \u003d Al 4 +3 with 3 -4 (carbide a?);

Saa + 3c \u003d c +2 O + CAC 2 (CA carbide);

C + 2H 2 \u003d C -4 H 4 (methane).

Recovery properties for coal are more characteristic:

With ° + o 2 \u003d CO 2.

Coal restores Fe, Cu, Zn, Pb and other metals from their oxides, for example:

2ZNO + C ° \u003d 2ZN + C +4 O 2.

At high temperatures, carbon interacts with oxygen, nitrogen, halogens and many other metals.

Carbon oxide (Ii) CO is formed in the process of combustion of coal with a lack of oxygen:

2C + O 2 \u003d 2SO.

In the monoxide molecule, a triple chemical bond, therefore CO is characterized by a low melting point and low solubility in water. In industry, CO is obtained by carbon dioxide transmission over hot coal at high temperatures:

CO 2 + C \u003d 2SO.

Due to the flow of this reaction, the exhaust gases of cars contain Co, also contain CO, exhaust furnaces with stoves with bad thrust.

In the carbon monoxide laboratory, the formic acid is obtained by adding to concentrated sulfuric acid, which takes water from it:

Nson Co + N 2 O.

Sorrelic acid when heated with sulfuric acid gives a mixture of two oxides:

H 2 C 2 0 4 \u003d CO + C0 2 + H 2 O.

The mixture of the obtained gases is passed through a hydroxide solution of barium, which absorbs only CO 2.

Physiological action . Carbon monoxide is very poisonous, the deadly dose of CO in the air is 0.2%. With hemoglobin of blood CO binds more than oxygen, thereby blocking the transfer of oxygen in the body. Signs of poisoning with small doses: Blood is unusually bright color, strong headache, sometimes loss of consciousness.

Properties. Carbon oxide (CO) is a colorless gas, heavier than air, a little soluble in water. It is absorbed by activated carbon, as well as a filtering layer containing I 2 O 5. Carbon oxide at ordinary temperatures is chemically inert, however, with the participation of catalysts, it reacts with hydrogen to form hydrocarbons. Due to the presence of mean-free steam in carbon and oxygen, carbon monoxide is a ligand and forms durable complexes with transition metals, for example, ,,,. At high temperatures with restores many metals from their oxides:

CO + CUO \u003d CU + CO 2.

This property of carbon oxide (II) is used in the smelting of metals from ores. Connecting with gray, forms a thiooxide:

Connecting with chlorine, forms phosgene:

CO + C? 2 \u003d SOS? 2.

Phosgen (SOS? 2) is a colorless gas with a weak smell. Highly poison, first world War It was used as a suffocating and poisoning agent. Phosgen is slowly hydrolyzed by water to form salt and coal acids:

SOS? 2 + 2ND \u003d H 2 CO 3 + 2NS?.

Carbon dioxide CO 2 is formed in nature when combustion and rotting organic substances. In the air, its concentration is 0.03%, it also contains in many mineral springs (Narzan, Borjomi). The atmosphere of Venus by 95% consists of CO 2. Carbon dioxide is assimilated in the process of photosynthesis with green plants with the help of their chlorophyll; At the absorption of solar energy in plants, organic substances are formed (primarily glucose), and oxygen is released and stands out into the atmosphere. The absorbed energy during dissimulation in living organisms of animals and plants is released again. The dissimulation of organic substances in organisms is the process of their oxidation in the presence of enzymes to form carbon dioxide and water:

Similar documents

The physical properties of the elements of the main subgroup of the group III. General characteristic of aluminum, boron. Natural inorganic carbon compounds. Chemical properties of silicon. Carbon interaction with metals, non-metals and water. Properties of oxides.

presentation, added 04/04/2017


Basic classes of inorganic compounds. Prevalence chemical elements. General patterns of chemistry of S-elements I, II and III groups of the periodic system D.I. Mendeleeva: physical, chemical properties, methods of obtaining, biological role.

tutorial, added 02/03/2011


The overall characteristics of the elements of VIA subgroups, their receipt, physical and chemical properties, distribution in nature. Hydrogen and oxygen compounds of chalcogen. Justification of the degrees of oxidation + IV, + VI. Main areas of sulfuric acid.

presentation, added 11.08.2013


Calcium as one of the most common elements on Earth, its main physical and chemical properties, the history of discovery and research. Finding an element in nature, the sphere of its practical application. Existing compounds and biological role.

examination, added 01/26/2014


Atomic, physical and chemical properties of the elements of the subgroup of copper and their connections. The content of the elements of the copper subgroup in the earth's crust. The use of pyro- and hydrometallurgyrical processes to obtain copper. Properties of copper, silver and gold connections.

abstract, added 06/26/2014


General characteristics of chemical elements of the IV group of the Mendeleev table, their stay in nature and compounds with other non-metals. Getting Germany, tin and lead. Physico-chemical properties of metals subgroup titanium. Scope of zirconium.

presentation, added 04/23/2014


The overall characteristic of the elements of the group I, their chemical and physical properties, History of the opening and features of methods of obtaining. Lithium and its connections. Patterns in the structure of alkali metal atoms. Rules for the storage of some elements of this group.

presentation, added 30.11.2012


Characteristics and group value of p-elements. The degree of their oxidation. The condition of the atoms of chalcogen. The properties of halogens. Subgroup of aluminum, nitrogen and carbon. Main mineral forms of boron. Prevalence in the earth's crust different species Minerals.

presentation, added 04/22/2016


Metals. Metals production methods. Chemical properties of metals. Characteristics of metals of the main subgroup I group. Characteristics of the elements of the main subgroup of group II. Characteristics of the elements of the main subgroup of the group III. Aluminum. Transition metals

abstract, added 05/18/2006


Element of the main subgroup of the second group, the fourth period of the periodic system of chemical elements D. I. Mendeleev. The history and origin of the name. Finding calcium in nature. Physical and chemical properties. The use of metallic calcium.

The P-elements of the periodic system include elements with valence p-sublayers. These elements are located in III, IV, V, VI, VII, VIII groups, main subgroups. In the period, the orbital radii atoms with an increase in the atomic number are reduced, and in general it grows. In subgroups of elements with an increase in the element number, the sizes of atoms are generally increasing, and decreases. p-Elements of the Group III TO p-Elements III The group includes, Gary Ga, India in and Tall Toll. According to the nature of these elements, Bor is typical non-metallol, the rest are metals. Within the subgroup, a sharp transition from nonmetal to metals is traced. The properties and behavior of the boron are similar, which is the result of the diagonal affinity of the elements in the periodic system, according to which the displacement in the right period causes an increase in non-metallic nature, and down the group - metallic, so elements are similar to the properties are located diagonally near, for example Li and Mg, Ber and Al, B and Si.

The electronic structure of the valence suite of the p-elements of the group III is basically a state of NS 2 NP 1. In boron compounds and trivalent, gallium and indium, in addition, can form compounds from +1, and for thallium the latter is quite characteristic.

p-elements of the group VIII The P-elements of the VIII groups include HE helium, Neon Ne, Argon Ar, Kripton Kr, Xenon XE and Radon RH, which make up the main subgroup. Atoms of these elements have completed external electronic layers, therefore the electronic configuration of the valence suits of their atoms is basically the state of 1S 2 (not) and NS 2 NP 6 (other elements). Due to the very high stability of electronic configurations, they are generally characterized by large values \u200b\u200bof ionization energies and chemical inertia, so they are called noble (inert) gases. In a free state, they exist in the form of atoms (monatomic molecules). Helium atoms (1S 2), neon (2s 2 2p 6) and argon (3S 2 3p 6) have a particularly stable electronic structure, so the bonding type connections are unknown for them.

Crypton (4S 2 4p 6), xenon (5S 2 5p 6) and radon (6S 2 6p 6) differ from previous noble gases by large sizes of atoms and, accordingly, lower ionization energies. They are capable of forming connections that often have low resistance.

Most compounds known on Earth are compounds of P-elements, five of them (C, N, P, O, S) are organogenic, that is, they are part of any cell. P-elements are located in the main subgroups with III to the VIII group. Valence electrons are located on the outer p-pylon, the overall electronic formula of the external level corresponds to the composition of NS 2 NP A, where A \u003d 1 - 6. P-elements show a positive degree of oxidation equal to the number of the group. In the nature of intermediate degrees of oxidation, the "parity rule" is manifested - elements of odd groups show the odd degrees of oxidation, and the elements of even groups are even. Negative oxidation degrees are manifested by elements, starting with 4 A subgroups.

In the period from left to right, atomic radii of p-elements decrease, the value of the ionization energy increases, which leads to increasing non-metallic and oxidative properties P-elements. In subgroups, metal properties and stability of lower degrees of oxidation increase in the subgroups.

Selenium, fluorine, bromine and iodine are microelements and are in the body in the form of ions with oxidation degree - 2 for selenium and -1 for halides. Ion Cl - is a macroelectric. The p-elements in the lowest positive degree of oxidation show toxic effect, while in the highest are microelements.

The manual presents a brief description of The biological action of the most important R-elements.

Nitrogen - The main component of the air: its volume fraction is 78.2%. The simplest nitrogen compounds are ammonia and ammonium salts formed as a result of catabolism, as well as during the decomposition of plants and animal organisms. Ammonium ions cannot penetrate the cell membranes, the ammonia molecules easily overcome the membrane barriers and quickly affect the brain, which was previously used in medical practice during fainting. Ammonia - toxic gas that can affect when inhaling mucous respiratory tract, cause shortness of breath and inflammation of the lungs.

Nitrogen oxide (II) NO may be formed in the atmosphere under the action of thunderstorm discharges by equation:

N 2 + O 2 ¾® 2NO

In the late 1980s, it was found that NO is synthesized by endothelial cells using an NO-synthase enzyme from arginine amino acid. No time no exceeds seconds, but the normal functioning of blood vessels is impossible without his participation. This compound provides relaxation of the smooth muscles of vessels, regulates the work of the heart, the immune system, is involved in the transfer of nerve pulses, sexual excitation. It is assumed that NO plays an important role in learning and memorizing. In 1988, for the opening of properties NO was awarded Nobel Prize (Furchgott, Ignarro, Murad).

Nitrogen oxide (IV) NO 2 is a strong oxidizing agent. It is formed from nitrogen oxide (ιι) by equation 2NO + O 2 ¾® 2NO 2.

Nitrogen oxide NO 2, released in large quantities when combustion of fuel on power plants, may cause acid rain. Acid rains lead to a decrease in the pH of the lakes and the death of the fish affect the structure of soils, which causes the death of crops and trees.

When inhaling nitrogen oxides in the lungs, nitrogen and nitrate acid is formed, correcting, the ulceration of the lungs, and with long-term inhalation - tumors. The reactions of interaction of nitrogen oxides with water are shown below

2NO 2 + H 2 O → HNO 3 + HNO 2

N 2 O 3 + H 2 O → 2hno 2

N 2 O 4 + H 2 O → HNO 3 + HNO 2

N 2 O 5 + H 2 O → 2hno 3

Nitrites (NO 2 -), used as preservatives of meat products, form a nitroxy acid HO-N \u003d O, which is the amino group of proteins with formation of the reaction by reaction:

R 2 N-H + HO-N \u003d O ® R 2 N-N \u003d O + H 2 O.

Nitrosyamine give meat and sausages pink-red color. In the high concentrations of nitrosoamine, a toxic effect is shown, they may cause bladder cancer. Nitrites can oxidize the Fe +2 cation (hemoglobin) to Fe +3 cation (methemoglobin):

HBFE 2+ + NO 2 - ® HBFE +3 + NO

This is one of the causes of the toxic effect of nitrites.

Nitrates (NO 3 -), present in food products, getting into the body, are easily restored to toxic nitrites. The high content of nitrates in water can lead to a stomach cancer (under reduced acidity), cause child mortality. In medicine, nitrogen compounds are used as a narcotic (nitrogen oction), diuretic (ammonium chloride), anti-nonya (nitroglycerin), antitumoriyev (EMBICHIN), Radio protection (Merkin) funds. Methyline, dimethylamine, diethylamine and others. Aliphatic amines are used in the synthesis of drugs ..

Phosphorus It is an organogen, the total mass proportion of this macroelement in the human body is 0.95%. Phosphorus is contained in bone tissue, kidneys, muscles, liver, blood, milk, hair, nails and teeth. Phosphates in living organisms serve structural components Skeleton. The residue of phosphoric acid enters the structure of phospholipids cell membranes, nucleic acids, complex carbohydrates. Polyphosphates (three and diphosphates) are involved in the accumulation of energy in the form of macroeergic bonds (for example, ATP, creatine phosphate). About 30 g of ATP is present in the human body, the energy of hydrolysis of ATP is the main energy currency that provides a cycle of energy in the cell.

Phospholipids form a bilayer structure of biological membranes. Phosphorus in the form of phospholipids is mainly concentrated in the brain (12%), in the liver (5%), milk (2-3%) and blood serum (0.6%). However, the main amount of phosphorus - 600 g is contained in the bone tissue, which is 85% of the mass of the entire phosphorus located in the human body. In solid tissues of teeth, phosphorus is in the form of hydroxyl-, chloro-, fluoropatite general formula Ca 5 (PO 4) 3 x, where x \u003d it, cl, f, respectively. The main mineral component of the bone tissue is calcium hydroxyphosphate Ca 5 (PO 4) 3 OH, called hydroxyapatite. The exchange of phosphorus in the body is closely related to calcium exchange, but this connection is antagonic. With an increase in the content of calcium in the blood, there is a decrease in phosphate content, primarily inorganic.

Phosphorus enters the body with food - milk, meat, fish, bread, vegetables, eggs, etc. The daily need for phosphorus is 0.8-1.2 g, the excess of phosphates contributes to the loss of manganese and calcium, which leads to osteoporosis.

In medicine, many phosphorus compounds are used as medicinal preparations for the treatment of heart disease, liver, stomach. Zinc phosphates are used as sealing materials in dentistry.

Oxygen refers to organogen. In the organism of an adult, a mass of 70 kg contains approximately 43 kg of oxygen. Together with hydrogen, oxygen forms a water molecule, the content of which in the body of an adult average is about 55 - 65%.

Oxygen is part of proteins, nucleic acids and other vital components of the body. Oxygen is necessary for breathing. The exothermic reaction of the oxidation of biomolecules (fats, proteins, carbohydrates, amino acids) serves as a source of energy for the body. The participation of oxygen (O 2) is carried out phagocytic (protective) functions of the body, as well as respiratory processes. The main amount of oxygen enters the body through the lungs, penetrates into the blood and with the participation of hemoglobin is delivered to all organs and tissues. Oxygen enters the body through the lungs, penetrates blood, binds to hemoglobin and forms easily dissociating compound - oxygemoglobin, and then from the blood comes into all organs and tissues. Almost all oxygen is metabolized to carbon dioxide and water and excreted from the body through light and kidney.

Molecular oxygen (O 2) is usually not entering direct non-enzymatic chemical reactions with organic compounds. The response involving 2 in the living cell is most often occurring in the active center of oxidase enzymes or oxygenase. In the course of these reactions, intermediate recovery products are formed, which in the reaction center of enzymes are subjected to transformations to carbon dioxide and water. With the participation of a number of enzymes (xanthinoxidase), hemoglobin in the body is generated by intermediate oxygen reduction products, the so-called active forms of oxygen (AFC) with high reactivity.

These include superoxide anion radicals (about 2), hydrogen peroxide (H 2 O 2), hydroxyl radicals (O), as well as oxygen molecules in the singlant state (O 2 * ). (The basic state of oxygen molecules is a triplet, for which it is characterized by the favor of two unpaired electrons with the same spin on different π * orbital). The formation of AFC proceeds according to the scheme:

1. One-electron recovery of 2, leads to the formation of a superoxide anion radical (2 ), which is the attorney of other AFK:

O 2 + E → O 2

This reaction proceeds, in particular, when the hemoglobin is oxidized, and the electron is transferred to the oxygen released in the reaction

Fe 2+ - E → Fe 3+

2. Anion-radical superoxide, dismantia, adjustable by the enzyme superoxiddismutase (SOD), is formed by hydrogen peroxide (H 2 O 2):

O 2. + O 2. + 2N + → H 2 O 2 + O 2

3. The formation of a hydroxyl radical (it) occurs when hydrogen peroxide interacts with superoxide anion radical or valence variable metal ions:

H 2 O 2 + O 2 → But + he ─ + o 2

H 2 O 2 + FE +2 → But + it ─ + Fe +3 (Fenton Reaction)

The fanton reaction reflects the toxic effect of hydrogen peroxide to hemoglobin, since the oxidation of the Fe +2 cation is occurred to the FE +3 cation, aggravated by the formation of the hydroxyl radical;

4. Singlentic oxygen (O 2 *) is formed when the oxygen molecule is excited in a triplet state under the action of a light quanta (Hυ). As a result, an electronic rearrangement of the molecule occurs, in which electrons with opposite directed spins are located on one or different π * orbital:

It is also possible to form 2 * by reaction between super-oxide anion with radical and hydroxyl radical:

O 2 + BUT → O 2 * + it ─

AFK play an important role in the vital activity of the body. For example, an anion radical superoxide is involved in activating phagocytic cells (neutrophils, macrophages, monocytes, eosinophils) necessary to destroy foreign microorganisms, tumor cells. AFC is involved in the processes of apoptosis (spontaneous death of cells, organs or the body as a whole).

The processes of EFC formations normally flow in the body and are regulated by antioxidant protection enzymes (superoxiddismutase, catalase, glutathioneer peroxidase, glutathionerans).

catalase

2 H 2 O 2 H 2 O + O 2

superoxiddismutaza

O 2 · _ + O 2 · _ + 2N + H 2 O 2 + O 2

glutathionepeoxidase

R-sh + H 2 O 2 2 H 2 O + R-S-S-R

R-S-S-R + 2N + + 2E 2 R-SH

The excess amount of AFC leads to the development of a number of pathological conditions, which are based on oxidative transformation of biological membranes lipids, damage to the structure of nucleic acids, proteins and their supramolecular complexes. These transformations are conditionally generally submitted by the scheme:

Rh + OH ∙ → R ∙ + H 2 O

R ∙ + O 2 → RO 2 ∙

Rh + RO 2 ∙ → ROOH + R ∙

The strengthening of free radical oxidation processes leads to a violation of the integrity of biological membranes and cell death, causes changes in the structure of proteins, reducing the activity of enzymes, is the cause of mutations.

In medicine, molecular oxygen is used to treat hypoxic states, cardiovascular diseases, cyanide and carbon monoxide poisoning. The dosage effect of oxygen is carried out at elevated pressure (hyperbaric oxygenation), as a result of which hemodynamics and oxygen support of the tissues are improved. In cardiovascular diseases, oxygen foam (oxygen cocktail) is used to improve metabolic processes. The subcutaneous administration of oxygen (ozone) is shown in trophic ulcers, gangrene. Ozonating drinking water is used for cleaning and disinfection.

Carbon - the most important organogen. The total carbon content is about 21% (15 kg per 70 kg of total body weight). Carbon is 2/3 masses of muscles and 1/3 of the mass of bone tissue. The physiological role of carbon is determined by the fact that this element is part of all organic compounds and takes part in all biochemical processes in the body. The oxidation of biomolecules under the action of oxygen leads to the formation of water and carbon dioxide (CO 2), which is a stimulator of the respiratory center, plays an important role in regulating respiration and blood circulation.

In free type, carbon is not toxic, but many of its compounds have significant toxicity: Co ( carbon monoxide), CSI 4 carbon four-chloride, CS 2 servo carbon, HCN cyanistic acid salts, benzene with 6 H 6, phosgene Sii 2, and a number of others. Carbon dioxide at a concentration of over 10% causes acidosis (reduction of blood pH), shortness of breath and palsy of the respiratory center. In pharmacy and medicine, various carbon compounds are widely used - derivatives of coalic acid and carboxylic acids, polymers, etc. Carbollane (activated carbon) is used to adsorption of gases and removal from the organism of various toxins, graphite in the form of ointments is used to treat skin diseases. In medical and biological studies, the products labeled 14 S.

Sulfur refers to macroelements, organogen. The sulfur is involved in the formation of compounds to the degree of oxidation -2. In the form of sulfydril - SH groups or disulfide bonds - S - s- sper is part of proteins, amino acids (cysteine, cystine, methionine), hormones (insulin), enzymes (coenzyme A), vitamins (in 1), Kerotina (hair , bones, nervous fabric). The tertiary structure of the protein contains disulfide bridges between the cystine residues of amino acids. The reversible transition of thiol groups in disulfide bonds protects the body from radiation lesions and the actions of strong oxidizing agents:

R 1 - S- S-R 2 R 1 - SH + R 2 - SH

R-S - H R-S - H S-R 1

PB 2+ → PB 2+

R 1 -S - H R 1 -S H - S-R

As a result, the enzyme loses activity and breaks the flow of biochemical reactions. In the process of metabolism of sulfur compounds, endogenous sulfuric acid is formed, which participates in the neutralization of poisonous compounds (phenol, indole) produced in the intestine by microorganisms. Sulfuric acid binds many xenobiotics in relatively harmless substances (conjugates), derived with urine.

Toxic sulfur compounds are H 2 S hydrogen sulfide, SO 2 sulfur gas. H 2 S hydrogen sulfide is contained in sulfur mineral waterswhich in the form of baths are used to treat a number of diseases. This is a colorless gas with an unpleasant smell. It is formed under the rotting of plant and animal residues under the action of microorganisms.

SO 2 - sulfur gas, has a suffocating smell. Poisonous. Acts as an irritant of the mucous membrane of the respiratory tract. Approximately one third of the sulfur oxide (IV) enters the atmosphere due to the microbiological oxidation of organic substances, its source is the active volcanoes. About 70% SO 2 is formed as a result of burning petroleum products and sulfur ore. Under the action of sunlight and catalysts (V 2 O 5) SO 2 oxide turns into SO 3:

2SO 2 + O 2 → 2SO 3

Incoring in atmospheric moisture SO 3 forms sulfuric acid, which forms acid rains, leading to the death of forests, soil acidification.

SO 3 (g) + H 2 O (g) → H 2 SO 4 (water)

Sodium thiosulfate Na 2 S 2 O 3 is used in medical practice as a counter-toxic, anti-inflammatory agent in poisoning with mercury, lead, hydroflicic salts. Sodium thiosulfate and precipitated sulfur are used in the treatment of scabies.

Many metals sulfates are used as medicines: Na 2 SO 4 '10H 2 O - as a laxo, MgSO 4 '7H 2 O - as a laxative and choleretic agent, CUSO 4 '5H 2 O and ZNSO 4 '7H 2 O as antiseptic, Binding, vomit. VASO 4 is used as a contrast with a radiographic study of the esophagus and stomach. Sulfur besieged is used in the treatment of scabies.

The body of the sulfur comes with food. The richest joints of sulfur eggs, meat, cottage cheese, buckwheat, bran, coarse bread.

Chlorine The human body is contained in an amount of 100 g (0.15%) mainly in the form of chloride ion. Chloride ion has an optimal radius for penetration through the cell membrane. This is explained by his joint participation with sodium and potassium ions in the creation of a certain osmotic pressure and regulating the water-salt metabolism. The daily need for sodium chloride is 1 g NaCl is necessary for the production of chloride (hydrochloric acid) in the stomach that plays an important role in the digestive process destroying various pathogenic bacteria (cholera, typhoid).

Vital chloride - ions do not have a toxic effect, while elemental chlorine is highly toxic gas.

In recent years, it has been established in the body of a number of active forms of halogen (AFG) - halogen-containing compounds with an increased reactivity and formed in a living organism or entering it as a result of human contact with environmental.

Active forms Halogens (AFG) is halogen-containing compounds with an increased reactivity and formed in a living organism or entering it as a result of human contact with the environment. The exogenous (introduced) and endogenous (formed in the body) of AFG are distinguished. Exogenous sources of active forms of halogen include pesticides, pharmaceuticals, anesthetics, wastewater, car exhaust gases and aircraft, industrial poisons. The active forms of halogens are formed in the body with the participation of peroxidase enzymes, in particular myeloperoxidase, as well as H 2 O 2-Creditases mainly in neutrophils. Chloridium and bromide ions are formed by chlorinous NCL and bromnomatic new acid (primary AFG), which can become sources of formation of active chlorine and bromine, as well as the products of halogenation of the most important biomolecules: amino acids, lipids, nucleic acids, cholesterol (secondary AFG) (see scheme).

Cl 2 + H 2 O → H + + SLˉ + HOCL

The active forms of halogens in small quantities are necessary to destroy and neutralizing microorganisms, with their redundant level, they can serve as sources of active free radicals that have a damaging effect on the structures of the body.

In cases where the appearance or education of Afg exceeds the ability of the body to remove or neutralizing these compounds, numerous pathologies may develop, including atherosclerosis, heart attacks, strokes, vasculitis, Alzheimer's disease, respiratory, renal dysfunction, rheumatoid arthritis, sepsis, etc.

Selenium It is a trace element, mainly concentrated in the liver and kidneys. The concentration of selenium in the blood is 0.001 - 0.004 mmol / l.

In the living organisms undoubted the connection of Selena with sulfur. At large doses, selenium is first accumulated in nails and hair, the basis of which is sulfur-containing amino acids. Obviously, selenium as an analog of sulfur replaces it in various connections:

R- S- S- R ¾® R - SE-SE- R

It has been established that the lack of selenium leads to a decrease in the concentration of glutathioneer-peroxidase enzyme, which, in turn, leads to the oxidation of lipids and sulfur-containing amino acids.

In recent years, studies have shown that selenium in a complex with any acid is included in the active centers of several enzymes: formate dehydrogenases, glutathionesondase and glutathionic and aloxidase, glutathioneransferase. In particular, the active center of glutathioneer peroxidase contains the residue of the unusual amino acid selenocysteine: noOC-CH (NH 2) -CH 2 -SE-H. This enzyme together with protein glutathione protects cells from the destructive effect of organic peroxides ROOH and hydrogen-hydroxide H 2 O 2. It is possible that the hydrogenide group - SEH selenocysteine \u200b\u200bhas some advantages compared with the hydrogen-fluid group -sh in the mechanism of action of this and other selenium-containing enzymes.

The ability of selenium is well known to prevent the body from the poisoning of mercury Hg and CD cadmium. It turned out that selenium contributes to the binding of salts of these toxic metals with active centers of other enzymes, to which their toxic effect does not affect.

It is shown that selenium stimulates the formation of antitel and thereby increases the protection of the body to infectious and colds. Participates in the development of erythrocytes, contributes to the maintenance of sexual activity. In a male body, almost 50% of the selenium focused on the seed tubes of the testicles, selenium is lost with ejaculate. Therefore, the need for men in Selena is higher than for women. The activity of the selenium increases in the presence of vitamin E. The fact of the relationship between the high content of selenium in the diet and low mortality from cancer is established.

In large doses selenium toxic. The decay of selenium compounds in the body of animals leads to the release of high-tech dimethyl selene CH 3 -SE-CH 3, having garlic smell. Installed the mechanism of this reaction. In the interaction of selenium acid H 2 SEO 3 with glutathione, compounds containing the -S-S-S- group are formed

H 2 SEO 3 + 4GSH ¾® GSSESG + GSSG + 3H 2 O

restored oxidized

glutathione glutathione

Under the action of enzymes compound containing a group

S-SE-S- is restored to the separator H 2 SE, which is methylated to form a toxic dimethyl selene.

In the diet of most industrialized countries, a microelement deficit is noted. The need for an adult is 150-200 μg / day. It is contained in meat, liver, kidneys, sea fish, yeast, bread, sinambur. However, often required additional sources Selena, which are vitamin and mineral kits and other biologically active supplements to food.

In medicine, selenium compounds (sodium selenitis, selenium-methionine, selenium-cysteine, etc.) are widely used for the treatment and prevention of many diseases, since selenium is a natural antioxidant. In dermatology and cosmetology, selenium-containing shampoos, cream, soap and gels are used. The isotope 15 SE as part of the selenium and sodium selenite is used in medical research.

Iodine refers to the number of essential biogenic trace elements. The human body contains about 25 mg (4 · 10 -5%) iodine, its large half is in the thyroid gland in the structure of hormones (triiodothyronine, thyroxine). In the form of iodide-ion I, about 1% of the iodine present in the body is located.

The main source of iodine for the human body is seafood, as well as used in food Industry iodofors and iodized salt. The amount of iodine in fruits and vegetables depends on the composition of the soil, as well as on the type of product processing. The thyroid gland is able to concentrate iodine, the content of element in it is 25 is higher than in the blood plasma. Thyroid gland secretes thyroxine hormones and triiodothyronine. There is evidence that iodine affects the synthesis of some fats proteins, hormones.

The reduced activity of the thyroid gland (hypothyroidism) may be associated with a decrease in its ability to accumulate iodide ions, as well as with a disadvantage of Iodine food (endemic goiter). In case of endemic zob, the drugs of iodine are prescribed: potassium iodide ki or sodium iodide NAI in doses corresponding to the daily need of a person in iodine (0.00L g potassium iodide). In areas where there is a deficiency of an iodine, nai or ki (i, 0 - 2.5) g / kg of salt is added to the prevention of endemic goiter to the cook salt).

With increased activity of the thyroid gland (hyperthyroidism) due to excessive synthesis of thyroid hormones, an increase in the speed of metabolic processes is observed.

NAI and KI are used with inflammatory respiratory diseases. Jodium preparations are used externally as antiseptics (for example, iodoform), as irritating and distracting means for inflammatory diseases of the skin and mucous membranes. The preparations containing iodine include: 5% iodine alcohol solution, anti-asthmatic medicine, potassium and sodium iodide, calcium-odid, antusumumin tablets and iodontiva.

Fluorine is a trace element. Fluorine compounds are concentrated in bone tissue, nails, teeth. The teeth include about 0.01% fluorine, most and most of the enamel, which is associated with the presence of a workfluorous fluoropatite Ca 3 (PO 4) 3 F. The lack of fluorine in the body leads to crys of the teeth. The mineral base of dental tissues - dentin is hydroxylapatite Ca 5 (PO 4) s (O), Ca 5 (PO 4) sloe and Fluoropatite Ca 5 (PO 4) 3 F. Fluoride-ion easily replaces the hydroxide ion in the hydroxylapatite, forming Protective enamel layer of more solid fluoropatite:

Ca 10 (PO 4) 6 (O) 2 + F ~ ¾® Ca 10 (P0 4) F 2 + 2 OH~

In addition, fluoride ions contribute to the deposition of phosphate calcium, accelerating the process of remineralization (crystal formation):

1O CA 2+ + 6PO 4 ~3 + 2F ~ ¾® 3CA 3 (PO 4) 2 + CAF 2

The caries of the teeth is a process of dissolving the hydroxylapathite components of the enamel under the influence of acids produced by bacteria:

Ca 5 (PO 4) 3 it + 7h + ¾® 5CA 2+ + 3H 2 PO 4 - + H 2 O

There are assumptions that with insignificant damage to the enamel, the administration of sodium fluoride contributes to the formation of fluoropatite that facilitates the remineralization of the damage. Fluoridation of sodium water fluoride (to the content of fluoride ions 1 mg / l) leads to a significant decrease in the incidence of the population by caries of teeth.

Sodium fluoride is consumed in medical practice as a local existing outdoor. NAF application is based on fluoropatite formation:

NAF + Ca 10 (PO 4) 6 (OH) 2 ¾® NaOH + Ca 10 (PO 4) 6 F 2

paste Tooth fabric

At the same time, simultaneously accumulates the medium of the oral cavity and neutralization of acids produced by bacteria.

Fluorine compounds enter the body with food and water. Many fluorine in rice, beef, eggs, milk, bows, spinach, apples.

Not only the flaw is harmful, but also an excess of fluorine. When the content of fluorine in drinking water Above the maximum permissible norm (1.2 mg / l), the dental enamel becomes fragile, it is easily destroyed and other symptoms of chronic fluorine poisoning appear - an increase in the fragility of bones, bone deformations and the overall depletion of the body. The disease occurred in this case is called fluorosis (fluorozom).

Bromine - trace element. The mass of bromine in the human body is about 7 mg (~ 10 -5%). The biological role of bromine compounds is not sufficiently clarified. It is localized in the glands of internal secretion, primarily in the pituitary gland, kidneys, thyroid gland, intercellular fluid. Increased content of anion bromide contributes to the excavation of the kidney chloride anions. There is evidence that bromine compounds inhibit the function of the thyroid gland and enhance the activity of the adrenal cortex. The most sensitive to the introduction into the organism of bromide ions is the CNS. Bromides are accumulated in various parts of the brain, reinforcing brake processes in the cortex neurons, therefore bromine preparations (potassium bromide, sodium, bromomfora) are used as calming funds at elevated excitability, contribute to the restoration of the impaired equilibrium between the processes of excitation and braking

In the ion radius, electronegativity and other physicochemical characteristics of the bromine occupies an intermediate position between chlorine and iodine. Therefore, the ion bromide can replace ions C1 - and I - in the body. An example of such interchangeability is the substitution of the iodine bromo in an excess of bromine in the body in the hormones of the thyroid gland, which leads to hyperthyroidism.

In connection with various individual sensitivity, the dosage of bromine preparations varies from 0.05 to 2.0 g. The body of the bromine comes with grain, nuts and fish.

Boron . It has long been known that the microelement borine is needed by higher plants, but the data on his biological role appeared relatively recently - since 1985 it was established that the Bohr participates in carbon-phosphate exchange, interacts with a number of biologically active compounds (carbohydrates, enzymes, vitamins, hormones) . It has been established that Bor is a partner of silicon, calcium, manganese, magnesium participating in the processes of calcification, the formation of bone tissue and prevent osteoporosis. In the mechanism of its influence on calcium exchange in women in postmenopausus, an important role plays an increase in the level of active estrogen. Bohr is involved in activation and estrogen and vitamin D. Under the influence of boron, calcium is reduced with urine and increasing the level of 17-β-estradiol. Bora preparations prevent the loss of calcium with urine, which is important in osteoporosis and fractures. Bor together with zinc is involved in mobilizing fatty acids from fat cells. Boric preparations weaken pain in the joints and improve well-being. The most effective and safe organic derivatives of the trace element, for example, boron glycerolinat. Inorganic derivatives - boric acid and the borax can have a toxic effect. Buru - Na 2 B 4 O 7 · 10N 2 Tetraboot 2 B 4 O 7 · 10N 2 o 7 · 10n 2 o is widely used as an antiseptic. The pharmacological effect of the drug is due to hydrolysis of salt with the release of boric acid:

Na 2 B 4 O 7 + 7N 2 O ¾® 4N 3 in 3 + 2NAOH

Formed alkali and acid cause coagulation (denaturation) of microbial cell proteins.

In progressing, boric acid H 3 in 3 is used as a form filler when casting dentures. The composition of dental pastes used as a glue-layer for dentures includes sodium NAB0 2 metabolism in a mixture with aluminum hydroxide A1 (OH) 3.

The daily need for the bore is approximately 2-7 mg. Borop sources are fruits, vegetables, nuts, wines.

The use of foods with a large content of boron violates the exchange of carbohydrates and proteins in the body, which leads to the occurrence of endemic intestinal diseases - enteritis.

Aluminum It is an immunototoxic trace element. The human body contains 10 -5% aluminum and daily comes from 5 to 50 mg. The source of aluminum is food and drinking water. With age, the content of this element in the lungs and the brain increases. Aluminum is involved in the formation of phosphate and protein complexes, the processes of regeneration of bone, connecting and epithelial tissue, has a braking or activating effect (depending on the concentration) on digestive enzymes, affects the function of the nearby-shaped glands.

The medicine uses adsorbing, enveloping, antacid, protective and painkillers of drugs containing aluminum. Aluminum silicate (white clay, kaolin) and burnt Kai (SO 4) 3 · 7H 2 O are used externally in the form of springs, ointments and pastes in the treatment of skin diseases. AI (OH) 3 is used as an antacid for ulcer of stomach and duodenum, gastritis and poisoning. AI (OH) 3, together with MGO, is part of the Almagel preparation used as an enveloping and antacid agent for the diseases of the stomach. Aluminum phosphate has an anti-rich, adsorbing effect, reduces the acidity of gastric juice.

Arsenic - Immunotoxic trace element, is contained in the human body in an amount (10 -6%). Arsenic accumulates in bones and hair and for several years is not completely output from them. This feature is used in the forensic examination to determine the question, whether the poisoning of arsenic compounds had a poisoning.

In the human body, arsenic compound comes with drinking and mineral water, grape wines and juices, seafood, medical preparations, pesticides and herbicides. Arsenic can enter the body in elevated amounts with atmospheric air, because The concentration of it in the air is increased by burning coal in boiler rooms and CHP, near the copper-smelting plants. In drinking water in some regions of the world (India, Bangladesh, Taiwan, Mexico), arsenic content is increased (1mg / l), which is the cause of mass chronic poisoning with arsenic and causes the so-called "black foot" disease. Arsenic (V) compounds and in features arsenic (III) are very toxic. The mechanism of toxic is explained by the ability of arsenic to block sulfhydryl SH - groups of enzymes, proteins, amino acids (cysteine, glutathione, lipoic acid).

In addition, arsenic can replace iodine, selenium and phosphorus, disrupting the biochemical processes of metabolism in the body, AS is an antimetabolic of these elements. The deadly dose for a person is approximately 0.1-0.3 g of arsenic.