General and bioorganic chemistry

(lecture notes)

Part 2. Organic Chemistry

For students of 1 course of the medical faculty of specialty "Stomatology"

Publishing house of the Russian University of Friendship Peoples,

U t in e r y d e n o

Rice scientist council

Russian University of Friendship Peoples

Kovalchukova O.V., Avramenko O.V.

General and bioorganic chemistry (lecture ability). Part 2. Organic Chemistry. For students of 1 course of the medical faculty of specialty "Stomatology". M.: Publishing House Rudn, 2010. 108 p.

The abstract of lectures readable for students of 1 course of the medical faculty of specialty "Dentistry". Circuited in accordance with the program of the course "General and Bioorganic Chemistry".

Prepared at the Department of General Chemistry.

© Kovalchukova O.V., Avramenko O.V.

© Publishing House Russian University of Friendship Peoples, 2010

Introduction

Bioorganic chemistry is a section of chemistry, which is closely associated with such special disciplines of medical faculties of universities, like biochemistry, pharmacology, physiology, molecular biology. It is an area of \u200b\u200bscience that studies the structure and mechanisms for the functioning of biologically active molecules from the standpoints and representations of organic chemistry, which determines the patterns in the relationship of the structure and the reactivity of organic compounds.

The main focus of the present course of lectures is given to the classification of organic compounds on the structure of the carbon skeleton and the nature of functional groups, regularities connecting the chemical structure of organic molecules with the nature of their reactionary centers, the relations of their electronic and spatial structure with the mechanisms of chemical transformations.

Theory of the chemical structure of organic compounds

Organic compounds - These are carbon compounds (except the simplest), in which it exhibits valence IV.

Organic chemistry- These are chemistry of hydrocarbons and their derivatives.

The carbon atom in organic compounds is in an excited state and has four unpaired electron:

6 with 1S 2 2S 2 2P 2 → 6 C * 1S 2 2S 1 2p 3

The carbon atom in the excited state is capable of:

1) to form strong bonds with other carbon atoms, which leads to the formation of chains and cycles;

2) as a result of various types of hybridization of orbitals, form simple, double and triple bonds between carbon atoms and with other atoms (H, O, N, S, P, etc.);

3) to connect with four different atoms, which leads to the formation of branched carbon chains.

Types of hybridization of carbon atom in organic compounds

sP 3 - hybridization

All four valence orbital participate in hybridization. Valenny angle 109 о 28 '(tetrahedron). Carbon atoms form only simple (σ) links - a saturated connection.

sP 2 - hybridization

Three hybrid and one non-liberal orbital are formed. Valence angle 120 o (flat structures, correct triangle). Hybrid orbital form σ-bonds. Unhybrid orbitals form p-communications. sP 2.-Hypebridization is characteristic of non-permanent compounds with one P - bond.

sP - hybridization

Two hybrid and two non-librid orbitals are formed. Valence angle 180 o (linear structures). Carbon atom sp.-Hybridization takes part in the formation of two double bonds or one triple bond.

The theory of the structure of organic compounds Formulated in 1861 A.M. Butlerov and includes the following provisions:

1. All atoms included in the molecule are related to each other in a strictly defined sequence in accordance with their valences. The order of the connection of atoms in the molecule determines it chemical structure .

2. The properties of organic compounds depend not only on the qualitative and quantitative composition of substances, but also on the order of their compound (the chemical structure of the molecule).

3. Atoms in the molecule have a mutual influence on each other, i.e. The properties of groups of atoms in the molecule may vary depending on the nature of other atoms that are part of the molecule. A group of atoms determining the chemical properties of organic molecules is called functional group .

4. Each organic compound has only one chemical formula. Knowing the chemical formula, you can predict the properties of the compound, and studying its properties in practice, to establish the chemical formula.

Organic molecule

Types of carbon skeleton:

Acyclic:

· Branched;

· Normal (linear).

Cyclical:

· Carbocyclic (cycle only from carbon atoms);

· Heterocyclic (except carbon atoms in the cycle consists of some other atoms - nitrogen, oxygen, sulfur).

Types of carbon atoms in the hydrocarbon chain:

H 3 C-CH 2 -CH-S-CH 3

Primary carbon atoms (connected in chains with only one carbon atom, is terminal);

A secondary carbon atom (connected to two adjacent carbon atoms is in the middle of the chain);

A tertiary carbon atom (located on the branching of the carbon chain, is connected to the three carbon atoms);

A quaternary carbon atom (does not have other substituents, except carbon atoms).

Functional group- a special group of atoms, which determines the chemical properties of the compounds.

Examples functional groups:

-IS HE- Hydroxyl group (alcohols, phenols);

C \u003d O.- carbonyl group (ketones, aldehydes);

FROM- carboxyl group (carboxylic acids);

-NH 2 -amino group (amines);

-Shh -tiolny Group (Thiospirts)

organic connection

structure

Properties

Chemical structure

Atoms included in the organic compound can be connected differently in the molecule. For example, two chemical compounds that have different physical and chemical properties can be responsible for compounding C 2 H 6 o.

Structure The organic compound is the number of atoms of various elements of the included in its molecule. Isomers- Compounds having the same composition, but a different chemical structure. Isomers have various chemical properties.

Types of isomeria

Structural isomeria

Male carbon chain:

Isomerius of the position of multiple relations:

Interclative isomeria:

Stereoisomeria

Geometric (spatial, cis-trans.- Iomeria compounds with double connections):

cis-Butene-2.	trance-Butene-2.

Geometric isomerism is possible if each of the carbon atoms involved in the formation of a double bond has different substituents. So, for Bootena-1 CH 2 \u003d CH-CH 2 -CH 3, geometric isomerism is not possible, since one of the carbon atoms at a double bond has two identical substituents (hydrogen atoms).

Geometric (spatial, cis-trans.- Iomeria cyclic limit connections):

Geometric isomerism is possible if at least two carbon atoms forming a cycle have different substituents.

Optical:

Optical isomerism is a type of stereoisomeria caused by the chirality of molecules. In nature there are compounds that relate as two hands of one person. One of the properties of these compounds is their incompatibility with its mirror reflection. This property is called chirality (from Greek. « from heir » - hand).

The optical activity of molecules is detected under the action on them polarized light. If, through a solution of an optically active substance, the polarized beam of light skip, then it will rotate the plane of its polarization. Optical isomers are denoted using prefixes d-

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Section: Organic Chemistry

Topic: The subject of organic chemistry.

The theory of the structure of organic compounds

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Explanatory note to the methodological manual

Methodological manual is intended for in-depth study of the topic « Types of hybridization of carbon atom ».

Practice shows that many students are hampered in determining the types of hybridization of carbon atoms and types of chemical bonds in the study of organic compounds.

The purpose of the manual is to help students learn to determine the types of hybridization of carbon atoms and types of chemical bonds in organic compounds.This manual is recommended for students of 1 course specialty 34.02.01 Nursing. The manual contains theoretical material on the topic, tables to systematize knowledge, exercises for independent work and deployed answers for each of the tasks.

The manual is aimed at the formation of self-work skills with educational material, the implementation of the search and use of information, the formation and development of creative potential, an increase in interest in discipline.

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Types of hybridization of carbon atom

The electronic structure of the carbon atom is in the main state of 1s 2 2S 2 2P 2, two unpaired electricones are located on the 2-level p-orbitals. This allows carbon atom to form only two covalent bonds on the exchange mechanism. However, in all organic compounds, carbon forms four covalent bonds, which becomes possible as a result of hybridization of atomic orbitals.

Hybridization is the interaction of atomic orbitals with close energy values \u200b\u200baccompanied by the formation of new "hybrid" orbital.

Hybridization is a process that requires energy costs, but these extension costs are compensated by the energy released in the formation of a larger number of covalent bonds. The formed "hybrid" orbital has the form of assimetric dumbbells and are sharply different from the initial orbitals of the carbon atom.

For carbon atom, three types of hybridization are possible: sP 3 -hybridization - Interactive orbitals are shown in blue arrows:

sP 2 -hybridization:

sr-hybridization:

Hybrid orbital carbon atoms are able to participate in education only-communications, unaffected by hybridization of p-orbitals form only - communications. This particular feature determines the spatial structure of organic substances molecules.

Hybridization
atomic orbitals of carbon

Covalent chemical bond is formed with the help of general binding electronic pairs by type:

Form a chemical connection, i.e. Create a common electron pair with a "foreign" electron from another atom, only unpaired electrons can only. Unpaired electrons when recording electronic formulas are located one in the orbit cell.
Atomic orbital. - This is a function that describes the density of the electronic cloud at each point of the space around the atom kernel. The electronic cloud is a space area in which an electron can be detected with a high probability.
To coordinate the electronic structure of the carbon atom and the valence of this element, we use ideas about the excitation of the carbon atom. In a normal (unexcited) condition, carbon atom has two unpaired 2 r 2 -electron. In the excited state (when absorbing energy) one of 2 s. 2 -electrons can go to free r-orbital. Then four unpaired electron appear in the carbon atom:

Recall that in the electronic formula of the atom (for example, for carbon 6 C - 1 s. 2 2s. 2 2p. 2) large numbers in front of the letters - 1, 2 - denote the number of the energy level. Letters s. and r Indicate the form of an electronic cloud (orbital), and the numbers on the right above the letters talk about the number of electrons on this orbital. Everything s.-Evubitals spherical:

At the second energy level except 2 s.-Exted three 2 r-Ibed. These 2 r-Evubitals have an ellipsoid form similar to dumbbells, and are oriented in space at an angle of 90 ° to each other. 2. r-Evubitals denote 2. r h. , 2r y. and 2 r z. In accordance with the axes along which these orbital are located.

Form and orientation
r-electronic orbitals

In the formation of chemical bonds, electronic orbitals acquire the same form. So, in limit hydrocarbons is mixed alone s.-Orbital and three r-Evuboli carbon atom with the formation of four identical (hybrid) sP 3 -Orbital:

It - sP 3-hybridization.
Hybridization - Alignment (mixing) of atomic orbitals ( s. and r) with the formation of new atomic orbitals called hybrid orbitals.

Four SP 3-hybrid orbital
carbon atom

Hybrid orbitals have an asymmetric shape, elongated toward the attached atom. Electronic clouds are mutually repelled and are located in space as far away from each other. With this axis four sP3-hybrid orbitals It turns out to be directed to the tops of the tetrahedron (correct triangular pyramid).
Accordingly, the angles between these orbital are tetrahedral, equal to 109 ° 28.
The vertices of electronic orbitals can overlap with orbitals of other atoms. If electronic clouds overlap through the line connecting the centers of atoms, then such a covalent connection is called sigma( ) - Communication. For example, in an ethane molecule C 2 H 6, a chemical bond is formed between two carbon atoms by overlapping two hybrid orbitals. This is off. In addition, each of carbon atoms in its three sP 3 Outbides overlap with s.-Evubitals of three hydrogen atoms, forming three-means.

Electronic cloud overlapping scheme
in the ethan molecule

In total, three valence states with different types of hybridization are possible for the carbon atom. Besides sP 3-hybridization exists sP 2 - I. sP-hybridization.
sP 2 -Hybridization - mixing one s.- and two r-Evubitals. As a result, three hybrid are formed. sP 2 - Lord. These sP 2 The bidded are located in the same plane (with axes h., w.) And aimed to the vertices of the triangle with an angle between orbitals 120 °. Non-mentioned
r-Orbital is perpendicular to the plane of three hybrid sP 2 -Orbital (oriented along the axis z.). Upper half r-Evubitals are located above the plane, the lower half is under the plane.
A type sP 2 carbon hybridization occurs in compounds with a double bond: C \u003d C, C \u003d O, C \u003d N. Moreover, only one of the bonds between two atoms (for example, C \u003d C) may be-means. (Other binding orbital atoms are directed in opposite parties.) The second bond is formed as a result of overlapping non-librid r-Obitals on both sides of the line connecting the nuclei of atoms.

Orbital (three SP 2 and one r)
carbon atom in SP 2-hybridization

Covalent bond formed by side overlapping r-Evubitals of neighboring carbon atoms, called pi ( ) - Communication.

Education
- Communication

Due to the smaller overlapping of the orbitals, there is less durable, than -ce.
sP-Hybridization - this is mixing (alignment in shape and energy) one s- and one
r-Evubitals with the formation of two hybrid sP-Evubitals. sP-The exorbitals are located on the same line (at an angle of 180 °) and are directed to the opposite sides of the carbon atom kernel. Two
r-Evubitals remain non-mentioned. They are posted mutually perpendicular
directions - Communications. On the image sP-Evubitals are shown along the axis y., and non-mentioned two
r-Evubitaly along the axes h. and z..

Atomic orbitals (two SP and two p)
carbon in the state of SP-hybridization

The triple carbon-carbon connection of the SS consists of a connection arising from overlapping
sp.-Hybrid orbitals, and two-beds.
The relationship of such parameters of the carbon atom, as the number of attached groups, the type of hybridization and types of chemical bonds formed, is shown in Table 4.

Covalent carbon ties

Number of groups
related
with carbon

A type
hybridization

Types
participating
chemical ties

Examples of formulas for compounds

sp. 3

Four - Communication

sp. 2

Three - Communication I.
one - Sound

sp.

Two - Communication
and two-beds

H-CC-H

Exercises.

1. What electrons of atoms (for example, carbon or nitrogen) are called unpaired?

2. Which means the concept of "general electronic pairs" in connections with a covalent bond (for example, CH 4. orH 2 S. )?

3. What electronic states of atoms (for example,FROM orN. ) Call basic, and what are excited?

4. Which means numbers and letters in the electronic formula of the atom (for example,FROM orN. )?

5. What is an atomic orbital? How many orbital at the second energy level of the atomFROM and how do they differ?

6. What is the difference between hybrid orbitals from the initial orbitals, of which they were formed?

7. What types of hybridization are known for carbon atom and what are they going to?

Answers to exercises

1. Electrons that are located one by orbitals are called unpaired electrons. For example, in the electron formula of the excited carbon atom - four unpaired electrons, and at the nitrogen atom - three:

2. Two electrons involved in the formation of one chemical connection are called a common electronic pair. Usually before the formation of a chemical bond, one of the electrons of this pair belonged to one atom, and the other electron is another atom:

3. The electron state of the atom in which the process of filling electronic orbitals is observed: 1S 2, 2S 2, 2P 2, 3S 2, 3P 2, 4S 2, 3D 2, 4P 2, etc., called the main state. An expendable state of one of the valence electrons of an atom occupies a free orbital with higher energy, such a transition is accompanied by a disconnection of paired electrons. Schematically, it is written so:

Whereas in the main state there were only two valence unpaired electrons, then four of such electrons becomes in the excited state.

5. Atomic orbital is a function that describes the density of the electronic cloud at each point of the space around the kernel of this atom. At the second energy level of the carbon atom, four orbitals are 2s, 2p x, 2p y, 2r z. These orbital differ:
a) form of an electronic cloud (s - ball, p - dumbbell);
b) p-orbitals have different orientation in space - along mutually perpendicular axes x, y and z, they are denoted by p x, p y, p z.

6. Hybrid orbitals differ from the initial (non-liberal) orbital form and energy. For example, S-orbital is a form of sphere, p - symmetric eight, SP-hybrid orbital - asymmetric eight.
Energy differences: E (s)< E(sр) < E(р). Таким образом, sp-орбиталь – усредненная по форме и энергии орбиталь, полученная смешиванием исходных s- и p-орбиталей.

7. For carbon atom, three types of hybridization are known: SP 3, SP 2 and SP (see the lesson text 5).

9. -Svyaz is a covalent bond formed by the frontal overlapping of orbitals along the line connecting the centers of atoms.
- Covalent bonds formed by side overlapping of p-orbitals on both sides of the line connecting atom centers.
- Communications show the second and third dash between the connected atoms.

10.

About hybrids we tell a lot. They are narrated by films, and books, as well as their science. In the first two sources of hybrids are very dangerous creatures. They can bring a lot of evil. But far from always hybridization is a bad phenomenon. It is often quite good.

An example of hybridization is every person. We are all hybrids of two people - Father and Mother. So, the fusion of the egg and spermatozoa is also a kind of hybridization. It is this mechanism that allows you to move the evolution. At the same time, hybridization with a negative sign. Let's consider this phenomenon as a whole.

General view of hybridization

However, not only biology includes this concept. And let the entry examined an example with hybrids as full-fledged individuals of incomprehensible biological species. In this case, this concept can be used in other sciences. And the value of this term will be somewhat different. But at the same time there is something in common yet. This is the word "union", which combines all possible values \u200b\u200bof this term.

Where does this concept exist?

The term "hybridization" is used in some sciences. And since most of the existing disciplines are intersecting, then we can safely talk about the use of each value of this term in any science, one way or another associated with natural research sectors. At the same time, the most actively given term is used in:

1. Biology. Hence the concept of a hybrid. Although, as always, when moving from science in everyday life there has been some distortion of facts. We understand the hybrid in the process of crossing the two other species in the process. Although it happens not always.
2. Chemistry. This concept means mixing several orbital - peculiar pathways of electrons.
3. Biochemistry. Here, the key concept is the hybridization of DNA.

As you can see, the third point is at the junction of two sciences. And it is absolutely normal practice. The same term can form at the junction of two sciences absolutely another value. Let's consider the concept of hybridization in these sciences in more detail.

What is a hybrid?

The hybrid is a creature that turned out in the hybridization process. This concept refers to biology. Hybrids can be obtained both by chance and specifically. In the first case, it may turn out animals that are created in the process of mating two varieties.

For example, they say that children who are neither of them are talking about cats and dogs. Sometimes hybrids are created specifically. For example, when cherry attach to Apricot, we are dealing with special hybridization.

Hybridization in biology

Biology is an interesting science. And the concept of hybridization in it is no less fascinating. Under this term implies the unification of the genetic material of different cells in one. It can be both representatives of one species and several. Accordingly, a division is divided into such varieties of hybridization.

• Internal hybridization. This is when two individuals of one species create a descendant. An example of intraspecific hybridization can be considered a person. It turned out in the process of fusion of the genital cells of representatives of one biological species.
• Interspear hybridization. This is when cross-like, but belonging to different types, animals. For example, a hybrid horse and zebra.
• Remote hybridization. This is when representatives though alone, but at the same time not combined with family connections.

Each of these species helps not only evolution. Scientists are also actively trying to cross different types of living beings. Best it turns out with plants. There are several reasons for this:

• Miscellaneous chromosomes. Each view has not only a specific amount of chromosomes, but also their set. All this interferes with reproduce offspring.
• Only hybrids plants can multiply. And that is not always.
• Poliploid can only be plants. So that the plant multiplied, it should become polyploid. In the case of animals, this is true death.
• The possibility of vegetative hybridization. This is a very simple and convenient way to create hybrids of several plants.

These are the reasons why crossed two plants is much easier and more efficient. In the case of animals, it may be possible to achieve the possibility of reproduction in the future. But at the moment, the official in biology is considered that animal hybrids lose the ability to multiply, since the data of individuals are genetically unstable. Consequently, it is not known what their reproduction can lead to.

Types of hybridization in biology

Biology - science is wide enough in its specialization. There are two types of hybridization that it provides:

1. Genetic. This is when one of two cells are made one with a unique set of chromosomes.
2. Biochemical. An example of this type is the hybridization of DNA. This is when complementary nucleic acids are combined into one DNA.

You can share for a greater number of varieties. But we did it in the previous subsection. So, remote and intraspecific hybridization are components of the first type. And there the classification is even more expanding.

The concept of vegetative hybridization

Vegetative hybridization is a concept in biology, which means such a kind of crossing of two plants, in which part of one species is coming on the other. That is, hybridization occurs due to the combination of two different parts of the body. Yes, so you can characterize the plant. After all, he also has its own bodies combined into a whole system. Therefore, if you call the plant by the body, there is nothing gallopped in it.

Vegetative hybridization has a number of advantages. It:

• Convenience.
• Simplicity.
• Efficiency.
• Practicality.

These advantages make such a variety of crossing very popular at gardeners. There is also a concept as somatic hybridization. This is when it is embossed not sex cells, but somatic, or rather, their protoplasts. This method of crossing is performed when it is impossible to create a standard sexual hybrid between several plants.

Hybridization in chemistry

But now we will be a little departing from biology and talk about another science. In chemistry there is its own concept, it is called "hybridization of atomic orbitals". This is a very complicated term, but if you deal a little in chemistry, there is nothing difficult in it. First you need to explain what orbital is.

This is a kind of way to which the electron is moving. We were taught in this school. And if such that these orbital data is mixed, a hybrid is obtained. There are three types of phenomenon called "hybridization of orbitals". These are such varieties:

• sP-hybridization is one s and other p orbital;
• sP 2 -Hypebridization is one S and two p orbital;
• sP 3 -Hypebridization - one S and three P orbitals are connected.

This topic is quite complicated for study, and it must be considered inextricably from the rest of the theory. Moreover, the concept of hybridization of orbitals concerns more than the end of this topic, and not start. After all, you need to explore the very concept of orbitals, what they are and so on.

conclusions

So, we figured out the values \u200b\u200bof the concept of "hybridization". This turns out to be quite interesting. For many it was a discovery that in chemistry there is also a given concept. But if this people did not know such people, what could they learn? And so, there is a development. It is important not to stop training erudition, since it will definitely characterize you from the good side.

Hybridization of atomic orbitals

The American scientist L. Poling advanced the idea of \u200b\u200bhybridization of atomic orbitals. According to this idea, if there is different atomic orbitals (AO) (S-, P-, D- or F-AO) (S-, P-, D-or F-AO), then the JSC hybridization occurs during the formation of chemical bond. Those. From different JSC are formed the same (equivalent) JSC. At the atom hybridized orbital, which have similar energy values. The idea of \u200b\u200bhybridization of AO is a convenient and visual reception of the description of complex processes occurring in the formation of chemical compounds. The shape of the hybrid AO differs from the form of the source JSC (Fig. 4.3).

Fig. 4.3. . Atomic SP-Hybrid Orbital

In the hybrid JSC, the electronic density shifts one way from the kernel. When the interaction of the hybrid orbital with a JSC of another atom, overlapping in the area of \u200b\u200bmaximum electron density, which leads to an increase in communication energy. This increase in communication energy compensates for the energy required for the formation of a hybrid orbital. As a result, chemical bonds formed by hybrid orbitals are stronger, and the resulting molecule is more stable.

If an atom in chemical bond is entering into an external valence level there are one S- and one p-electrons, then this atom in the process of formation formation occurs, SP-hybridization of JSC occurs (Fig. 4.4).

Fig. 4.4. SP-hybridization scheme

If at the atom entering the chemical bond, there are one S- and two p electrons on the outer shell, then in addition to SP-hybridization, SP 2-hybridization of AO of this atom can occur (Fig. 4.5).

Fig. 4.5. . SP 2-hybridization scheme

At an atom having one S- and three p-electrons on the outer shell, in addition to SP- and SP 2-hybridization, SP 3-hybridization of these JSC may occur (Fig. 4.6).

Fig. 4.6. . SP 3-Hybridization scheme

More complex types of hybridization are also possible with the participation of D-orbitals of atoms (Table 4.3).

As can be seen from Fig. 4.4-4.6, hybrid clouds in space are located symmetrically relative to each other, which reduces their mutual repulsion and, accordingly reduces the energy of molecules.

Table 4.3.

Spatial configuration of some compounds

4.1.4.2. The formation of σ-, π- and δ-links

Depending on the direction of overlapping electron clouds, S-, P- and δ-bonds are formed .

The bond formed by overlapping the AO along the line connecting the kernel of interacting atoms is called S-bond. Sigma-Communication may occur when overlapping two S-orbitals (Fig. 4.7), S- and P-orbitals, P-orbitals, D-orbitals, as well as D- and S-orbitals, D- and P-orbitals, as well as overlapping hybrid orbital with other types of orbitals and among themselves. Sigma-bond usually covers two atoms and does not extend beyond their limits, therefore is a localized two-centered relationship.

S-S.	P-P.	P-S.
SP N -S.	D-SP N	sp n -sp n

Fig. 4.7. Overlapping atomic orbitals in the formation of σ-links

Communication formed by overlapping non-librid p- and d-jo on both sides of a line connecting the nuclei of atoms (lateral overlaps) is calledπ - Communication. Pi-Communication can be formed when overlapping P-R-orbitals, R-D - orbitals, D - d-orbitals (Fig. 4.8), as well as F-P-, F-D- and F-F-orbitals.

Fig. 4.8.Overlapping atomic orbitals when forming π-links

Communication formed by overlapping D-orbitals by all four petals is called δ-bond (Fig. 4.9).

Accordingly, S-elements can form only σ-bonds, P-elements - σ- and π-bonds, D-elements σ-, π-, and δ-bonds, and F-elements - σ-, π-, δ- And even more complex ties. Due to the smaller overlapping, the strength in π- and δ-bonds is lower than that of σ-links.

Fig. 4.9.Direction of overlapping atomic D-orbitals in the formation of δ-links

The hybridization of atomic orbitals is a process that allows you to understand how atoms modify their orbitals in the formation of compounds. So what is hybridization, and what kind of types exist?

General characteristics of hybridization of atomic orbitals

The hybridization of atomic orbitals is a process in which various orbitals of the central atom mix are mixed, resulting in the same orbital in their characteristics.

Hybridization occurs in the process of forming a covalent bond.

The hybrid orbital has odds of an infinity sign or an asymmetrical inverted eight stretched away from the atomic nucleus. This form determines the stronger than in the case of pure atomic orbitals, overlapping hybrid orbitals with orbitals (pure or hybrid) other atoms and leads to the formation of more durable covalent bonds.

Fig. 1. Hybrid orbital appearance.

For the first time, the idea of \u200b\u200bhybridization of atomic orbitals put forward a US scientist L. Poling. He believed that in the chemical bonding of the atom there are different atomic orbitals (S-, P-, D-, F-orbitals), then the result is hybridization of these orbital. The essence of the process is that atomic orbitals are formed from different orbital.

Types of hybridization of atomic orbitals

There are several types of hybridization:

• . This type of hybridization occurs when one S-orbital S-orbital is mixed and one p-orbital. As a result, two full-fledged SP orbitals are formed. These orbital are located to the atomic core in such a way that the angle between them is 180 degrees.

Fig. 2. SP-hybridization.

• sP2 hybridization. This type of hybridization occurs when one S-orbital and two P-orbitals are mixed. As a result, three hybrid orbitals are formulated, which are located in one plane at an angle of 120 degrees to each other.
• . This type of hybridization occurs when one S-orbital and three P-orbitals are mixed. As a result, four full-fledged SP3 orbitals occurs. These orbital are directed to the top of the tetrahedron and are located to each other at an angle of 109.28 degrees.

sP3 hybridization is characteristic of many elements, for example, carbon atom and other substances of the group IVA (CH 4, SIH 4, SIF 4, GEH 4, etc.)

Fig. 3. SP3 hybridization.

More complex types of hybridization with the participation of D-orbitals of atoms are also possible.

What did we know?

Hybridization is a complex chemical process, when different orbital atoms form the same (equivalent) hybrid orbitals. The first theory of hybridization was voiced by American L. Poling. Three main types of hybridization are distinguished: SP-hybridization, SP2 hybridization, SP3 hybridization. There are also more complex types of hybridization in which D-orbitals participate.