Multiple covalent bonds are represented by non-existent organic slabs, which can be used to avenge the underlying and lost chemical bonds. To describe the nature of non-existent fields, L. Pauling introduces the concept of sigma- and π-links, hybridization of atomic orbitals.

Pauling's hybridization for two S- and two p-electrons made it possible to explain the straightening of chemical bonds, but the tetrahedral configuration of methane. To explain the structure of ethylene from chotyroh equal Sp3 - electrons of the carbon atom, one p-electron is taken apart to make an additional bond, which was called the π-bond. In this case, three Sp2-hybrid orbitals, which are left out, expand in the area under the 120° angle and form the main bonds, for example, a flat ethylene molecule.

At times, acetylene molecules in hybridization take part (according to Pauling) only one S-and one p-orbitals, with which two Sp-orbitals are dissolved, splayed under the hood at 180 ° and directed in the opposite direction. Two “pure” p-orbitals of carbon atoms intersect in pairs at mutually perpendicular planes, making two π-bonds of the linear acetylene molecule.

Look at L. Pauling, you know your tip from his book “The nature of a chemical link, as for a long time, became a chemist's bedside book. In 1954, L. Pauling received awards Nobel Prize z khіmії z formularyuvannya "For the investigation of the nature of the chemical bond and yogo zastosuvannya for the determination of the structure of folding shelves."

However, the physical change of hybridization of atomic orbitals became obscure, the hybridization was algebraic transformations, which could not be attributed to physical reality.

Linus Pauling, having tried the polypism description of the chemical linkage, including the vibrancy of the hybridization of orbitals in the molecules of non-existent half-shells, and created the theory of the curved chemical linkage. The same pre -dopy is a sympositical organic of the organic one, the binding of Pam'yatі Kekule (London, Veresen 1958), L. Poling, who was saving the navigable naval st ivasku yak Kombinatikh, however . On tsoma

symposia L. Pauling with the use of categorical stverzhuvav:

There may be chemists who are aware of what is superbly important for innovations ... the description of σ, π- description for the hinged chi-perfect link and the resulting systems will be replaced by the description for the help of curved links. I'm stubborn, what?

In Pauling's new theory, all the electrons that bind together become equal and equal to the lines that go behind the nuclei of the molecule. Pauling's theory of a curved chemical link protected the statistical interpretation of M. Born's hwyl function and the Coulomb electron correlation of electrons. The appearance of a physical difference - the nature of the chemical bond is largely determined by the electrical interaction of nuclei and electrons. The more electrons that connect, the smaller the nuclear gap and the smaller chemical bond between carbon atoms.

Tricentric chemical link

A further development of the chemical bond was given by the American physicist W. Lipscomb, who developed the theory of two-electron tricenter bonds and the topological theory, which allows the transfer of future hydrides to boron (boron).

An electron pair in a tricentric chemical bond becomes critical for three nuclei of atoms. The simplest representative of the tricenter chemical bond, the molecular ion water H3+, has an electron pair that takes a total of three protons.

The diborane molecule has several single covalent functions link B-H and two two-electron tricenter bonds. Internuclear insertion into a single covalent bond B-H becomes 1.19 Å, at the same time, similarly insertion into a tricentric bond B-H-B becomes 1.31 Å. The length of the tricentric bond B-H-B (φ) is 830. The combination of two tricentric bonds in the diborane molecule allows the nuclei of the atoms in boron to be trimmed at a distance dB-B = 2 1.31 sin φ/2 = 1.736 Å. The nuclei of compatible atoms are in the water in the distance in the plane, in a similar arrangement of single covalent bonds B-H, in the distance h = 1.31 · cos φ/2 = 0.981 Å.

Tricentric bonds can be realized not only in a tricot of two boron atoms and one atom of water, but also between three atoms of boron, for example, in frame boron (pentaborane - B 5 H 9, decaborane - B 10 H 4 and in.). In these structures, there are primary (kintsev) and enter to the tricenter linkage (mistkov) atom of water and tricots of atoms in boron.

The foundation of rams from their two-electron tricenter bonds with “mosquito” atoms destroyed the canonical theory of valence. The water atom, which had previously been a standard monovalent element, appeared bound by identical bonds to two boron atoms and became formally a divalent element. W. Lipscomb's robots deciphering the ram's life expanded the statement about the chemical link. The Nobel Committee was awarded the William Nunn Lipscomb Prize in Chemistry for 1976 for the formulation "For the investigation of the structure of rams (borhydrites), as to clarify the problems of chemical bonds).

Rich-centric chemical link

In 1951, a rotation of T.Kil and P. Poson was not taken during the synthesis of dicyclopentadiene, but a new saline organic part was taken away. Otrimannya, previously unfamiliarly stable, yellow-yellow-hot, crystal-clear half of the hall, has suddenly turned respect to itself.

E.Fischer and D.Wilkinson independently established the structure of a new side - two rings of cyclopentadiene were rolled in parallel, with balls, or in the form of a “sandwich” for the gap atom, rolled between them in the center (Fig. 8). The name "ferocene" was proponed by R. Woodward (actually, D. Whiting, a yoga buddy). In the new one, the presence of ten carbon atoms (zehn - ten) was shown to be evident in each atom.

There are ten links (C-Fe) in the ferrocene molecule equally, the value of the internuclear gap of Fe-c is 2.04 Å. All carbon atoms in the ferrocene molecule are structurally and chemically equivalent to skin linkage C-C 1.40 - 1.41 Å (for straightening, in benzene the C-C bond is 1.39 Å). For the first time, the 36-electron shell is vibrated near the atom.

In 1973, the brothers Ernst Otto Fischer and Jeffrey Wilkinson were awarded the Nobel Prize in Chemistry for the formulas "For innovative, vikonan, one kind of one robot, in the gallery of metal-organic, so-called sandwich shells." Indvar Lindkvist, a member of the Royal Swedish Academy of Sciences, at his promotional hour for the presentation of the laureates, stating that “this proves the new principles of connections and structures, which are rebuff."

In this hour, we will remove dicyclopentadiene, similar rich metals. Pokhіdnі transitional metals may have the very structure and the very nature of the bond, which is ferocene. Lanthanides do not establish a sandwich structure, but a construction that conjures up a three-promenade star.

Dibenzenechromium was omitted immediately after the ferocene. For the same scheme of withdrawal of dibenzene molybdenum and dibenzene vanadium]. In all units of this class, atoms and metal have a total of two six-membered rings. Uсі 12 zv'yazkіv metal-charcoal in these floors are identical.

Synthesis is also uranocene [bis(cyclooctatetraєn)uranium], in which the uranium atom takes two eight-membered rings. Uсі 16 stars uranium-coal in the uranocene are identical. Uranocene is taken in combination with UCl 4 and the sum of cyclooctatetraene and potassium in tetrahydrofuran at minus 300 °C.

Fig.1. The orbital radii of the elements (r a) and the length of the one-electron chemical bond (d)

The simplest one-electron chemical bond is created by a single valence electron. It appears that one electron in the building can take in total two positively charged ions. In a one-electron bond, the Coulomb forces of positively charged particles are compensated by the Coulomb forces of gravity of these particles to a negatively charged electron. The valence electron becomes hot for two nuclei of the molecule.

Butts of such chemical fields are molecular ions: H 2+ , Li 2+ , Na 2+ , K 2+ , Rb 2+ , Cs 2+ :

The polar covalent link is found in heteronuclear diatomic molecules (Fig. 3). The bonding electron pair in the polar chemical bond is close to the atom with the highest first ionization potential.

Vіdstan d mizh atomic nuclei, which characterizes the expanse structure of polar molecules, can be closely seen as the sum of covalent radii of the same atoms.

The linkage of the binding electron pair of one of the nuclei of the polar molecule is brought about until the appearance of an electric dipole (electrodynamics) (Fig. 4).

Stand between the centers of gravity of positive and negative charges is called the dove of the dipole. The polarity of the molecule, like the polarity of the bond, is estimated by the value of the dipole moment μ, which is the additional dipole strength l by the value of the electron charge:

Multiple covalent bonds

Multiple covalent bonds are represented by non-existent organic slabs, which can be used to avenge the underlying and lost chemical bonds. To describe the nature of non-existent fields, L. Pauling introduces the concept of sigma- and π-links, hybridization of atomic orbitals.

Pauling's hybridization for two S- and two p-electrons made it possible to explain the straightening of chemical bonds, but the tetrahedral configuration of methane. To explain the structure of ethylene from chotyroh equal Sp 3 - electrons of the carbon atom, one p-electron is taken apart to make an additional bond, which was called the π-bond. In this case, three Sp 2 -hybrid orbitals expand in a plane under the 120° angle and form the main bonds, for example, a flat ethylene molecule (Fig. 5).

In Pauling's new theory, all the connecting electrons became equal and equal to the lines that go behind the nuclei of the molecule. Pauling's theory of a curved chemical link protected the statistical interpretation of M. Born's hwyl function and the Coulomb electron correlation of electrons. The appearance of a physical difference - the nature of the chemical bond is largely determined by the electrical interaction of nuclei and electrons. The more electrons that connect, the smaller the nuclear gap and the smaller chemical bond between carbon atoms.

Tricentric chemical link

A further development of the chemical bond was given by the American physicist W. Lipscomb, who developed the theory of two-electron tricenter bonds and the topological theory, which allows the transfer of future hydrides to boron (boron).

An electron pair in a tricentric chemical bond becomes critical for three nuclei of atoms. In the simplest representative of the tricentric chemical bond - the molecular ion water H 3 + electron pair takes a total of three protons (Fig. 6).

Fig. 7. Diboran

The foundation of rams with their two-electron tricenter bonds with "mosquito" atoms destroyed the canonical theory of valence. The atom of water, which had previously become a standard monovalent element, appeared bound by identical bonds with two atoms of boron and became formally a divalent element. W. Lipscomb's robots deciphering the ram's life expanded the statement about the chemical link. The Nobel Committee was awarded the William Nunn Lipscomb Prize in Chemistry for 1976 for the formulation "For the investigation of the structure of rams (borhydrites), to clarify the problems of chemical bonds).

Rich-centric chemical link

Ferrocene molecule

Fig. 9. Dibenzenechromium

Fig. 10. Uranocene

There are ten links (C-Fe) in the ferrocene molecule equal to each other, the value of the internuclear gap of Fe-c is 2.04 Å. All carbon atoms in the ferrocene molecule are structurally and chemically equivalent; For the first time, the 36-electron shell is vibrated near the atom.

Dynamics of the chemical bond

Chemical sound to make dynamic. Thus, the metal bond is transformed into a covalent bond during the process of phase transition during evaporation of the metal. The transition of metal from solid to steam-like mill will require more energy.

In pairs, the assigned metals are practically composed of homonuclear diatomic molecules and free atoms. During the condensation of metal vapor, the covalent bond is transformed into metal.

Vaporization of salts with a typical ionic bond, for example, ionic metal fluorides, leads to the destruction of the ionic bond and the dissolution of heteronuclear diatomic molecules with a polar covalent bond. Whenever possible, the solution of dimeric molecules with local links.

Characteristics of the chemical bond in the molecules of fluoride in puddle metals and dimers.

During the condensation of vapors of fluorides in puddle metals, the polar covalent bond is transformed into an ionic bond with solutions of crystalline salt salts.

The mechanism of the transition of covalent to metal bonds

Fig.11. Spivvіdnennia between the orbital radius of the electron pair r e and the length of the covalent chemical bond d

Orientation of dipoles of diatomic molecules and the dissolved octahedral cluster fragment during the condensation of tin metal vapor.

Fig.13

Disperse gravity (London's force) zooms in on the interatomic interaction and the adoption of homonuclear diatomic molecules from atoms of tin metals.

The establishment of a covalent bond metal-metal is connected with the deformation of the electronic shells of interfering atoms - valence electrons create an electron pair, which is called, the electron gap is concentrated in the space between the atomic nuclei of the viniclo. A characteristic feature of the homonuclear diatomic molecules of puddle metals is the high strength of the covalent bond (3.6-5.8 times greater for the strength of the bond in the water molecule) and low energy and expansion.

Appointed spacing between r e and d indicates the unevenness of the distribution of electric charges in the molecule - in the middle part of the molecule, the negative electric charge of the happy electron pair, and on the ends of the molecule - the positive electric charge of the two atomic brushes.

The unevenness of the division of electric charges creates the mind and mutual modality of the molecules of the balance of orientation forces (Van der Waals forces). Molecules of lunar metals should be oriented in such a way that different electric charges appear side by side. Through war between molecules develop forces of gravity. Zavdyaks of the visibility of the rest, the molecules of the puddle metals are approaching and violently drawn together. At the same time, there is a deformity of the skin that is closer to the expansion of the poles of the vascular molecules (Fig. 12).

In fact, the links between the electrons of a diatomic molecule, which, while consuming in an electric field, some positively charged atomic cores of the molten metal molecules, are driven from the orbital radius of the atom and become free.

At the same time, the electron pair becomes cohesive for a system with six cations. We begin to build a crystal lattice of metal at the cluster stage. The crystalline lattice of puddle metals clearly shows the structure of the linking lanka, which has the shape of a created flattened octahedron - a square bipyramid, the height of which and the edge of the basis correspond to the value of the constant translational lattice a w (Fig. 13).

The value of the constant translational lattice a w of the puffer metal crystal significantly shifts the length of the covalent bond of the puffer metal molecule, which is important because the electrons in the metal are found in the free steel:

Mathematically, due to the power of the free electrons in the metal, sound out of the “upper Fermi”, as follows, as a geometrical space, where the electrons are located, without caring for the main power of the metal - conduct an electric stream.

When the process of condensation of puddle metal vapors with the process of condensation of gases, for example, water, is manifested characteristic in power metal. Just as during the condensation of water, weak intermolecular interactions are observed, then for the condensation of metal vapors, processes characteristic of chemical reactions occur. The very condensation of metal pairs in some stages and can be described by the onset process: a free atom → a diatomic molecule with a covalent bond → a metal cluster → a compact metal with a metal bond.

Interactions of halide molecules in puddle metals are accompanied by their dimerization. A dimeric molecule can be used as an electric quadrupole (Fig. 15). In this hour, we will see the main characteristics of dimers of halogenides of puddle metals (double chemical bond and valence cut between bonds).

Dovzhina khіmіchnogo linkage and valent kuti in dimers of halogenides of puddle metals (E 2 X 2) (gas phase).

In the process of condensation, the diya of orientational forces are strengthened, intermolecular interactions are accompanied by the decisions of clusters, and eventually, solid speech. The halogenides of tin metals make crystals with a simple cubic and volume-centered cubic lattice.

Type of crystal lattice and post-translational lattice for tin metal halides.

In the process of crystallization, there is an increase in the amount of nuclear energy, which leads to the formation of an electron from the orbital radius of the puddle metal atom and the transfer of the electron of the atom to the halogen with the dissolved ions. The force fields of the ions are evenly divided at all directions in the open space. In puddle metal crystals, the force field of the skin ion coordinates more than one ion with the opposite sign, as it is customary to represent the ionic bond (Na + Cl -).

In ionic crystals, the understanding of simple binary molecules of the type Na + Cl - and Cs + Cl - consuming sens, shards of ion metal binding from six chlorine ions (in sodium chloride crystals) and eight chlorine ions (in cesium chloride crystals. When to whom all the intervening places are in crystals of equal distance.

Notes

1. Doctor of inorganic chemistry. Constants of inorganic speeches. - M.: "Khimia", 1987. - S. 124. - 320 p.
2. Lidin R.A., Andreeva L.L., Molochko V.A. Doctor of inorganic chemistry. Constants of inorganic speeches. - M.: "Khimiya", 1987. - S. 132-136. – 320 s.
3. Gankіn V.Yu., Gankіn Yu.V. How the chemical bond is established and the chemical reactions proceed. - M.: publishing group "Kordon", 2007. - 320 p. - ISBN 978-5-94691296-9
4. Nekrasov B.V. Course of global chemistry. - M.: Derzhkhimizdat, 1962. - S. 88. - 976 p.
5. Pauling L. The nature of the chemical bond / edited by Ya.K. Sirkin. - prov. from English M.Є.Dyatkina. - M.-L.: Derzhkhimizdat, 1947. - 440 p.
6. Theoretical Organic Chemistry / Ed. R.H. Freudlin. - prov. from English Yu.G. Bundel. - M .: View. foreign literature, 1963. - 365 p.
7. Lemenovsky D.A., Levitsky M.M. Russian chemical journal (journal of the Russian chemical partnership named after D.I. Mendelyev). - 2000. - T. XLIV, vip.6. - S. 63-86.
8. Chemical Encyclopedic Dictionary/goal. ed. I.L.Knunyants. – M.: Glad. Encyclopedia, 1983. - S. 607. - 792 p.
9. Nekrasov B.V. Course of global chemistry. - M.: Derzhkhimizdat, 1962. - S. 679. - 976 p.
10. Lidin R.A., Andreeva L.L., Molochko V.A. Doctor of inorganic chemistry. Constants of inorganic speeches. - M.: "Khimia", 1987. - S. 155-161. – 320 s.
11. Gillespie R. Geometry of molecules/wires. from English E.Z. Zasorina and V.S. Mastryukov, for ed. Yu.A. Pentina. - M .: "Svit", 1975. - S. 49. - 278 p.
12. Doctor of Chemistry. - 2nd view., revised. that dod. - L.-M.: State Scientific and Technical Institute of Chemical Literature, 1962. - T. 1. - S. 402-513. – 1072 p.
13. Lidin R.A., Andreeva L.L., Molochko V.A. Doctor of inorganic chemistry. Constants of inorganic speeches. - M.: "Khimiya", 1987. - S. 132-136. – 320 s.
14. Ziman J. Electron in metals (introduction to the theory of the Fermi surface). Successes in physical sciences. - 1962. - T. 78, issue 2. – 291 p.

Div. also

• Chemical sound- article from the Great Radianskaya Encyclopedia
• Chemical sound- Chemport.ru
• Chemical sound- Physical Encyclopedia

Themes of the codifier ЄDI: Covalent chemical bond, various differences in the mechanism of illumination. Characteristics of the covalent bond (polarity and energy of the bond). Ionny call. Metallic sound. Water call

Intramolecular chemical bonds

On the back of the hand, you can see the links that vindicate between the particles in the middle of the molecules. Such links are called intramolecular.

Chemical sound between atoms of chemical elements may have an electrostatic nature that settles for a rahunok vzzaєmodії zvnіshnіh (valence) electronіv, more than a lesser world emphasizing positively charged nuclei linking atoms.

The key is here - ELECTRICITY. It itself determines the type of chemical bond between atoms and the power of that bond.

- The purpose of the building of the atom is to attract (trim) outrageous(Valenti) electronics. Electronegativity is determined by the degree of heavy electrons to the nucleus and deposit, most importantly, according to the radius of the atom and the charge of the nucleus.

Electronegativity is easy to define unambiguously. L. Pauling made a table of visible electronegativity (based on the energies of the bonds of diatomic molecules). The largest electronegative element - fluorine 3 values 4 .

It is important that in different necks it is possible to use different scales and tables for the value of electronegativity. Why not varto lakatisya, shards play a role in the adoption of a chemical bond atoms, and the won is approximately the same for any system.

If one of the atoms has a chemical bond A: If it attracts electrons more strongly, then the electron pair shifts to a new one. What is more difference of electronegativity atoms, the electron pair is more shifted.

This is the value of the electronegativity of interfering atoms equal or approximately equal: EO(A)≈EO(B), then the electron pair does not move to the same atom: A: B. Such a call is called covalent non-polar.

Even though the electronegativity of the interfering atoms varies, but not much (the difference in electronegativity is approximately 0.4 to 2: 0,4<ΔЭО<2 ), then the electron pair shifts up to one of the atoms. Such a call is called covalent polar .

As for the electronegativity of interfering atoms, it is obvious (the difference in electronegativity is greater than 2: ΔEO>2), then one of the electrons is practically more likely to pass to the next atom, ioniv. Such a call is called ionna.

Main types of chemical bonds covalent, ionnaі metaleva zv'azku. Let's take a look at their report.

Covalent chemical bond

covalent bond – tse chemical link , settled for rahunok settlement of the gambling electronic bet A: . At what at two atoms overlap atomic orbitals. A covalent bond is established by the interaction of atoms with a small difference in electronegativity (as a rule, between two non-metals) or atoms of one element.

The main dominance of covalent bonds

• straightening,
• insipidity,
• polarity,
• polarization.

The power of power is added to the chemical and physical power of speeches.

Straightening of the tongue characterizes the chemical nature of speech and its form. Kuti between two links are called valence. For example, in a water molecule, the H-O-H cut is 104.45 o, so the water molecule is polar, and in the methane molecule, the valence cut is H-C-H 108 o 28'.

Nasichuvanist - Tse zdatnіst аtomіv utvoryuvati obmezhenu kіlkіst covalent chemical zv'yazkіv. Kіlkіst zv'yazkіv, zdatnyh utvoryuvat atom, called.

Polarity vyazku vinikaє through nerіvnomіrny rozpodіl elektronї shіlnostі between two atoms with different electronegativity. Covalent bonds are divided into polar and non-polar.

Polarization zv'azku - tse the building of electronic communication is disturbed under the direction of the outside electric field(zocrema, electric field in the other part). Polarizability lies in the fragility of electrons. How far the electron is from the nucleus, how far the electron is from the nucleus, how far the molecule is more polarizable.

Covalent non-polar chemical bond

Use 2 types of covalent bonding - POLARі NON-POLAR .

butt . Let's take a look at the water molecule H2. The skin atom of water on the ovnіshnyu energy level carries one mismatched electron. To represent the atom, the Lewis structure is victorious - this is the scheme of the real energy level of the atom, if the electrons are indicated by dots. Models of Luis's point structures are badly supported by an hour of work with elements of another period.

H.+. H=H:H

Thus, the water molecule has one single electron pair and one H-H chemical bond. Tsya electron pair does not move to the same atom in water, because the electronegativity of atoms is the same. Such a call is called covalent non-polar .

Covalent non-polar (symmetrical) link - covalent bond, fusions by atoms with equal electronegativity (as a rule, with the same non-metals) and, also, with equal distribution of the electron density between the nuclei of atoms.

The dipole moment of non-polar bonds is equal to 0.

Apply: H 2 (H-H), O 2 (O \u003d O), S 8.

Covalent polar chemical bond

Covalent polar link - this is a covalent link, a kind of vinica atoms with different electronegativity (as a rule, different non-metals) and characterized displaced global electron wager to an electronegative atom (polarization).

The electronic gap is shifted to a larger electronegative atom - also, a smaller negative atom has a partial negative charge (δ+, delta +).

What is more important in the electronegativity of atoms, more polarity call and team more dipole moment . Between the solid molecules and the charges behind the sign, there are additional forces of gravity, which are greater mysticism zv'azku.

Polarity zv'azku vplivaє phyzichnі and khіmіchnі power spoluk. Depending on the polarity of the bond, lay down the mechanisms of reactions and develop the reactionary structure of the suicidal bonds. The polarity of the sound is most pronounced polarity of the molecule And, in such a rank, without intermediary, such physical power as the temperature of boiling and melting temperature, rozchinnist in polar retailers.

Apply: HCl, CO2, NH3.

Mechanisms for the establishment of a covalent bond

The covalent chemical bond can be blamed for two mechanisms:

1. Exchange mechanism the establishment of a covalent chemical bond - as long as the skin part is given for the establishment of a global electronic wager, one unpaired electron:

BUT . + . B = A:

2. The establishment of a covalent bond is such a mechanism, in which one of the particles gives an inconsistent electron pair, and another part gives a vacant orbital for the electronic bet:

BUT: + B = A: B

With which one of the atoms is given an incompetent electron pair ( donor), and the other atom has a vacant orbital for the bet ( acceptor). Through the war, enlighten the bond, the energy of the electrons will change, tobto. useful for atoms.

Covalent link, solutions behind the donor-acceptor mechanism, do not resent behind the dominance of other covalent bonds, established by the exchange mechanism. The illumination of a covalent bond by the donor-acceptor mechanism is carried out either with atoms or with a large number of electrons on the outer energy level (donors of electrons), or else, with a small number of electrons (acceptors of electrons). The report of the valence possibility of atoms was examined in the case of the species.

The covalent bond behind the donor-acceptor mechanism is established:

- at the molecule fumes CO(the bonds of the molecule are trinity, 2 bonds are adopted for the exchange mechanism, one for the donor-acceptor mechanism): C≡O;

- at ion ammonium NH 4 + , in ions organic amines for example, in methylammonium ions CH 3 -NH 2 + ;

- at complex services, chemical bond between the central atom and groups of ligands, for example, sodium tetrahydroxoaluminate Na bonds between aluminum and hydroxide ions;

- at nitric acid and salts- nitrates: HNO 3 , NaNO 3 in other halfs of nitrogen;

- at the molecule ozone O 3 .

Main characteristics of the covalent bond

A covalent bond, as a rule, settles between non-metal atoms. The main characteristics of a covalent bond are dozhina, energy, multiplicity and directness.

Multiplicity of chemical bonds

Multiplicity of chemical bonds - ce the number of double electron pairs between two atoms y each. The multiplicity of the bond can be easily determined from the value of the atoms that make up the molecule.

For example , In a molecule of water H 2, the multiplicity of bonds is more than 1, because in skin water, there is only one non-pairing electron on the outer energy level, therefore, only one electron pair is established.

Molecule of oxygen O 2 has a multiplicity of bonds equal to 2, because the skin atom has 2 unpaired electrons on the equal energy level: O=O.

In a molecule of nitrogen N 2, the multiplicity of bonds is more than 3, because the skin atom has 3 unpaired electrons each on the outer energy level, and the atoms make up 3 high electron pairs N≡N.

Dovzhina covalent bond

Dovzhina chemical bond - Tse stand between the centers of the nuclei of atoms, which will establish links. Її are determined by experimental physical methods. It is possible to estimate the value of the length of the linkage approximately, according to the rule of additivity, according to which the length of the linkage in the AB molecule is approximately equal to the sum of the lengths of the links in the molecules A 2 and 2:

The length of the chemical bond can be approximately estimated beyond the radii of atoms, scho appease zv'azok, or for the number of calls so the radii of the atoms do not change much.

At the time of the increase in the radii of the atoms, which make the connection, the strength of the connection will increase.

For example

With an increase in the multiplicity of the link between atoms (the atomic radii of which do not vanish, but slightly vanish), the length of the link will change.

For example . In a row: C–C, C=C, C≡C, the link changes.

Energy zv'azku

To the world of the minerality of the chemical bond is the energy of the bond. Energy zv'azku signifies the energy necessary for raising the link, that distance of atoms, which establishes this link, for an inexhaustibly large stand one in one.

Covalent bond є duzhe mіtsny.Її energy to become from a few tens to a few hundreds of kJ / mol. The greater the energy of the sound, the greater the power of the sound, and the other way around.

The value of the chemical bond is deposited according to the duration of the bond, the polarity of the bond and the multiplicity of the bond. The more chemical sound, the easier it is to tear it up, the less energy the sound, the lower the mentality. We have the shortest chemical link, the more powerful link, and the greater the energy of the link.

For example, in a number of spoluk HF, HCl, HBr change, because zbіshuєtsya dovzhina zv'yazku.

Ionic chemical link

Ionny call - Tse chemical link, foundations for electrostatic gravity of ions.

Іoni utvoryuyuyutsya at the process of accepting chi and giving electrons by atoms. For example, the atoms of all metals weakly diminish the electronic energy level. Therefore, for metal atoms, it is characteristic consolidating power- Healthy supply of electronics.

butt. Atom of sodium should be replaced by 3 energy equals 1 electron. Easily giving yoga, the sodium atom satisfies the richly stable ion Na + with the electronic configuration of the noble gas neon Ne. There are 11 protons and less than 10 electrons in the sodium ion, so the total charge of the ion is -10+11 = +1:

+11Na) 2) 8) 1 - 1e = +11 Na +) 2 ) 8

butt. The atom of chlorine on the level of energy equal to 7 electrons. In order to give the configuration of a stable inert atom to argon Ar, chlorine needs to receive 1 electron. After the arrival of an electron, a stable ion of chlorine is formed, which is formed from electrons. The total charge of the ion is healthy -1:

+17Cl) 2 ) 8 ) 7 + 1e = +17 Cl — ) 2 ) 8 ) 8

Give respect:

• The dominance of the ions rises against the dominance of the atoms!
• Stіykі іoni can not only atomy, ale i groups of atoms. For example: ammonium ion NH 4 +, sulfate-ion SO 4 2- and in. Chemical bonds made by such ions are also respected by ions;
• Ionny zv'yazok, as a rule, settles between themselves threwі non-throwers(groups of non-metals);

They, who have settled down, are attracted by the electric tension: Na + Cl -, Na 2 + SO 4 2-.

Nachno zagalnym vіdminnіst mіzh covalent and іonnymi types zvyazku:

Metallic chemical bond

Metalevy zvez'azok - tse zv'yazok, which appease shdo free electronics mizh metal ions that make up the crystal lattice

At the atoms of metals on the level of the energy level, the sound of roses from one to three electrons. The radii in the atoms of metals, ring out, great - henceforth, the atoms of metals, on the vіdmіnu of non-metals, it's easy to reach the zvnіshnі elektroni, tobto. є strong guides

Intermolecular interactions

Let’s take a closer look at the interdependencies that are blamed among other molecules in the speech. intermolecular interactions . Intermolecular interactions are such kind of interactions between neutral atoms, in which no new covalent bonds are formed. The forces of interaction between molecules were revealed by van der Waals in 1869, and named after him Van dar Waals with the forces. The van der Waals forces are shared on orientation, induction і dispersion . The energy of intermolecular interactions is much less than the energy of the chemical bond.

Orientation forces of gravity vinikayut between polar molecules (dipole-dipole interaction). Qi forces are between polar molecules. Induction interactions - The relationship between a polar molecule and a non-polar one. A non-polar molecule is polarized through a polar polarity, which gives rise to additional electrostatic gravity.

A special kind of intermolecular interaction - water linkage. - all intermolecular (or intramolecular) chemical bonds, which are blamed between molecules, in which there are strongly polar covalent bonds. H-F, H-O or H-N. Although there are bonds in the molecule, there can be links between the molecules additional forces of gravity .

Lighting mechanism of the water link is often electrostatic, and often donor-acceptor. In this case, an atom of a strongly negative element (F, O, N) acts as an electron pair donor, and an atom and a water atom, connected with these atoms, act as an acceptor. For watery zvezku characteristic straightening by the open space insipidity.

Vodneviy zv'yazok can be marked with dots: N ··· O. What is the greater electronegativity of the atom obtained with water, and what is the least dimness, the same is the least watery link. Vaughn is characteristic of us before the z'ednan fluoride with water , as well as up to oliyu with water , in a smaller world nitrogen with water .

Water links are blamed between such speeches:

— fluorine HF(gas, fluorohydride in water - hydrofluoric acid), water H 2 O (steam, ice, rare water):

— separation of ammonia and organic amines- between molecules of ammonia and water;

— organic slabs, in which the bond is O-H or N-H: alcohols, carboxylic acids, amines, amino acids, phenols, aniline and iodine, proteins, various carbohydrates - monosaccharides and disaccharides.

The watery lingering is added to the physical and chemical powers of the speeches. So, additional gravity between molecules makes the boiling of speeches easier. In speeches made of watery bonds, an abnormal rise in boiling temperature is observed.

For example As a rule, when the molecular weight moves, the boiling temperature of the speeches rises. However, in a number of speeches H 2 O-H 2 S-H 2 Se-H 2 Te we are not afraid of linear changes in boiling temperatures.

And yourself, at water temperature is abnormally high - Not less than -61 about C, as a straight line shows us, but more than +100 about C. This anomaly is explained by the presence of water links between water molecules. Otzhe, for extraordinary minds (0-20 o C) water є motherland behind the phase mill.