How to determine the type of hybridization in inorganic compounds. Types of ao hybridization

Instruction

Consider the molecule of the simplest saturated hydrocarbon methane. Its looks like this: CH4. The spatial model of a molecule is a tetrahedron. A carbon atom forms bonds with four hydrogen atoms that are exactly the same in length and energy. According to the above example, they involve 3 - P electron and 1 S - an electron whose orbital has become exactly the same as the orbitals of the other three electrons as a result of what happened. This type of hybridization is called sp^3 hybridization. It is inherent in all the ultimate.

But the simplest representative of unsaturated - ethylene. Its formula is as follows: C2H4. What type of hybridization is inherent in carbon in the molecule of this substance? As a result, three orbitals are formed in the form of asymmetric "eights" lying in the same plane at an angle of 120 ^ 0 to each other. They were formed by 1 - S and 2 - P electrons. The last 3rd P - the electron did not modify its orbital, that is, it remained in the form of a regular "eight". This type of hybridization is called sp^2 hybridization.

How are bonds formed in a molecule? Two hybridized orbitals of each atom entered into with two hydrogen atoms. The third hybridized orbital formed a bond with the same orbital of another. Are the remaining R orbitals? They are "attracted" to each other on both sides of the plane of the molecule. A bond has formed between the carbon atoms. It is the atoms with a "double" bond that sp^2 is inherent in.

And what happens in the acetylene molecule or? Its formula is as follows: C2H2. In each carbon atom, only two electrons undergo hybridization: 1 - S and 1 - P. The remaining two retained orbitals in the form of "regular eights" overlapping in the plane of the molecule and on both sides of it. That is why this type of hybridization is called sp - hybridization. It is inherent in atoms with a triple bond.

All the words, existing in a particular language, can be divided into several groups. This is important in determining both meaning and grammatical functions. the words. Assigning it to a specific type, you can modify it according to the rules, even if you haven't seen it before. Element types the words lexicology deals with the rnogo composition of the language.

You will need

- text;
- vocabulary.

Instruction

Select the word you want to type. Its belonging to one or another part of speech does not yet play a role, as well as its form and function in a sentence. It can be absolutely any word. If it is not indicated in the task, write out the first one that comes across. Determine whether it names an object, quality, action or not. For this setting, all the words are divided into significant, pronominal, numerals, service and interjection. To the first type include nouns, adjectives, verbs and . They denote the names of objects, qualities and actions. The second type of words that have a naming function is pronominal. The ability to name is absent in , interjection and service types. These are relatively small groups of words, but they are in everyone.

Determine if the given word is capable of expressing the concept. This feature has the words significant units of a significant type, because they form the conceptual range of any language. However, any number also belongs to the category of concepts, and, accordingly, also carries this function. Functional words also have it, but pronouns and interjections do not.

Consider what the word would be like if it were in a sentence. Can it be? It can be any word of significant type. But this possibility is also in, as well as in the numeral. And here are the official the words play a supporting role, neither subject nor nor minor members they cannot be sentences, as well as interjections.

For convenience, you can make a plate of four columns of six rows. In the top line, name the appropriate columns "Types of words", "Name", "Concept" and "Able to be a member of the sentence." In the first left column, write down the names of the types of words, there are five in total. Determine which functions the given word has and which it does not. In the appropriate column, put the pluses and. If there are pluses in all three columns, then this is a significant type. The pronominal pluses will be in the first and third columns, in the second and third. Service the words can only express the concept, that is, they have one plus in the second column. Opposite interjections in all three columns there will be minuses.

Hybridization: natural and artificial

The hybridization process is based on uniting in one cell genetic material different cells from different individuals. There is a difference between intraspecific and distant, in which the connection occurs different genomes. In nature natural hybridization happened and is happening without human intervention constantly. It was by interbreeding within a species that plants changed and improved and new varieties and breeds of animals appeared. From the point of view, there is a hybridization of DNA, nucleic acids, changes at the atomic and intraatomic levels.

In academic chemistry, hybridization is understood as a specific interaction in the molecules of a substance. atomic orbitals. But it's not real physical process, but only a hypothetical model, concept.

Hybrids in crop production

In 1694, the German scientist R. Camerarius proposed artificially obtaining. And in 1717, the English T. Fairchild first crossed different types carnation. Today, intraspecific hybridization of plants is carried out in order to obtain high-yielding or adapted, for example, frost-resistant varieties. Hybridization of forms and varieties is one of the methods of plant breeding. Thus, a huge number of modern crop varieties have been created.

With distant hybridization, when representatives of different species are crossed and different genomes are combined, the resulting hybrids in most cases do not give offspring or produce low-quality crossbreeds. That is why it makes no sense to leave the seeds of hybrid cucumbers that have ripened in the garden, and every time to buy their seeds in a specialized store.

Selection in animal husbandry

In the world, natural hybridization, both intraspecific and distant, also takes place. Mules have been known to man for two thousand years before our era. And at present, the mule and hinny are used in the household as a relatively cheap working animal. True, such hybridization is interspecific, therefore hybrid males are necessarily born sterile. Females very rarely give offspring.

A mule is a hybrid of a mare and a donkey. A hybrid obtained from crossing a stallion and a donkey is called a hinny. Mules are specially bred. They are taller and stronger than a hinny.

But crossing a domestic dog with a wolf was a very common activity among hunters. Then, the resulting offspring were subjected to further selection, as a result, new breeds of dogs were created. Today, animal breeding is an important component of the success of the livestock industry. Hybridization is carried out purposefully, with a focus on the specified parameters.

We hear a lot about hybrids. Films and books tell about them, and science also considers them. In the first two sources, hybrids are very dangerous creatures. They can bring a lot of evil. But hybridization is not always a bad thing. Quite often it is good.

An example of hybridization is each person. We are all hybrids of two people - father and mother. Thus, the fusion of the egg and sperm is also a kind of hybridization. It is this mechanism that allows evolution to move forward. In this case, there is also hybridization with a negative sign. Let's look at this phenomenon in general.

General idea of hybridization

However, not only biology includes this concept. And let in the introduction, an example was considered with hybrids as full-fledged individuals of an incomprehensible species. However, this concept can be used in other sciences. And the meaning of this term will be somewhat different. But at the same time, there is still something in common. This is the word "union", which combines all possible meanings of this term.

Where does this concept exist?

The term "hybridization" is used in a number of sciences. And since most of existing disciplines intersect, then we can safely talk about the use of each meaning of this term in any science, one way or another connected with natural research branches. At the same time, the most active this term used in:

Biology. This is where the concept of hybrid came from. Although, as always, when moving from science to everyday life there has been some misrepresentation. We understand a hybrid as an individual resulting from the crossing of two other species. Although this is not always the case.
Chemistry. This concept means mixing several orbitals - a kind of paths for the movement of electrons.
Biochemistry. Here key concept is DNA hybridization.

As you can see, the third point is at the junction of two sciences. And this is absolutely normal practice. One and the same term can form a completely different meaning at the junction of two sciences. Let's take a closer look at the concept of hybridization in these sciences.

What is a hybrid?

A hybrid is a creature that has turned out in the process of hybridization. This concept refers to biology. Hybrids can be obtained both by chance and on purpose. In the first case, it can turn out to be animals that are created in the process of mating two different species of creatures.

For example, they talk about how cats and dogs have children who are not one of them. Sometimes hybrids are created on purpose. For example, when a cherry is attached to an apricot, we are dealing with a special hybridization.

Hybridization in biology

Biology - interesting science. And the concept of hybridization in it is no less fascinating. This term refers to the combination of the genetic material of different cells into one. It can be either representatives of one species or several. Accordingly, there is a division into such varieties of hybridization.

intraspecific hybridization. This is when two individuals of the same species create a descendant. An example of intraspecific hybridization can be considered a person. It turned out in the process of merging the germ cells of representatives of one biological species.
Interspecific hybridization. This is when similar, but belonging to different species, animals interbreed. For example, a hybrid of a horse and a zebra.
distant hybridization. This is when representatives of at least one species interbreed, but at the same time they are not united by family ties.

Each of these varieties helps not only evolution. Scientists are also actively trying to cross different types of living beings. It works best with plants. There are several reasons for this:

different number of chromosomes. Each species has not only a specific number of chromosomes, but also a set of them. All this prevents reproduction of offspring.
Only hybrid plants can reproduce. And that is not always the case.
Only plants can be polyploid. For a plant to reproduce, it must become polyploid. In the case of animals, this is certain death.
Possibility of vegetative hybridization. This is a very simple and convenient way to create hybrids of several plants.

These are the reasons why it is much easier and more efficient to cross two plants. In the case of animals, perhaps in the future it will be possible to achieve the possibility of reproduction. But on this moment The official opinion in biology is that hybrid animals lose the ability to reproduce, since these individuals are genetically unstable. Therefore, it is not known what their reproduction may lead to.

Types of hybridization in biology

Biology is a fairly broad science in its specialization. There are two types of hybridization that it provides:

Genetic. This is when two cells are made into one with a unique set of chromosomes.
Biochemical. An example of this species is DNA hybridization. This is when complementary nucleic acids combine to form one DNA.

Can be divided into large quantity varieties. But we did this in the previous subsection. Thus, distant and intraspecific hybridization are components of the first type. And there the classification expands even more.

The concept of vegetative hybridization

Vegetative hybridization is a concept in biology that means a kind of crossing of two plants, in which part of one species takes root on another. That is, hybridization occurs due to the combination of two different parts organism. Yes, this is how the plant can be characterized. After all, he also has his own organs, combined into a whole system. Therefore, if you call a plant an organism, there is nothing wrong with that.

Vegetative hybridization has a number of advantages. This is:

Convenience.
Simplicity.
Efficiency.
Practicality.

These advantages make this type of crossing very popular with gardeners. There is also such a thing as somatic hybridization. This is when not germ cells are crossed, but somatic, or rather, their protoplasts. This method crossbreeding is done when it is impossible to create a hybrid by standard sexual intercourse between several plants.

Hybridization in chemistry

But now we will deviate a little from biology and talk about another science. In chemistry there is a concept, it is called "hybridization of atomic orbitals". This is a very complicated term, but if you understand a little about chemistry, then there is nothing complicated about it. First you need to explain what an orbital is.

This is a kind of path along which the electron moves. We were taught this at school. And if it happens that these orbitals different type mix to form a hybrid. There are three kinds of phenomenon called "orbital hybridization". These are the varieties:

sp hybridization - one s and another p orbital;
sp 2 hybridization - one s and two p orbitals;
sp 3 hybridization - one s and three p orbitals are connected.

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

findings

So, we figured out the meanings of the concept of "hybridization". This turns out to be interesting enough. For many, it was a discovery that chemistry also has this concept. But if such people did not know this, what could they learn? And so, there is development. It is important not to stop training erudition, as this will definitely characterize you on the good side.

Hybridization of atomic orbitals and the geometry of molecules

An important characteristic of a molecule consisting of more than two atoms is its geometric configuration. It is defined mutual arrangement atomic orbitals involved in the formation of chemical bonds.

Overlapping of electron clouds is possible only with a certain mutual orientation of electron clouds; in this case, the overlap region is located in a certain direction with respect to the interacting atoms.

Table 1 Hybridization of orbitals and spatial configuration of molecules

The excited beryllium atom has the configuration 2s 1 2p 1 , the excited boron atom - 2s 1 2p 2 and the excited carbon atom - 2s 1 2p 3 . Therefore, we can assume that not the same, but different atomic orbitals can participate in the formation of chemical bonds. For example, in such compounds as BeCl 2 , BeCl 3 , CCl 4 there should be bonds of unequal strength and direction, and σ-bonds from p-orbitals should be stronger than bonds from s-orbitals, because for p-orbitals, there are more favorable conditions for overlapping. However, experience shows that in molecules containing central atoms with different valence orbitals (s, p, d), all bonds are equivalent. The explanation for this was given by Slater and Pauling. They came to the conclusion that different orbitals, not very different in energy, form a corresponding number of hybrid orbitals. Hybrid (mixed) orbitals are formed from different atomic orbitals. The number of hybrid orbitals is equal to the number of atomic orbitals involved in hybridization. Hybrid orbitals are the same in the shape of the electron cloud and in energy. Compared to atomic orbitals, they are more elongated in the direction of formation of chemical bonds and therefore cause better overlap of electron clouds.

The hybridization of atomic orbitals requires energy, so hybrid orbitals in an isolated atom are unstable and tend to turn into pure AOs. When chemical bonds are formed, hybrid orbitals stabilize. Due to the stronger bonds formed by the hybrid orbitals, more energy is released from the system and therefore the system becomes more stable.

sp hybridization occurs, for example, in the formation of Be, Zn, Co, and Hg (II) halides. In the valence state, all metal halides contain on the corresponding energy level s and p-unpaired electrons. When a molecule is formed, one s- and one p-orbital form two hybrid sp-orbitals at an angle of 180 o.

Fig.3 sp hybrid orbitals

Experimental data show that all Be, Zn, Cd and Hg(II) halides are linear and both bonds are of the same length.

sp 2 hybridization

As a result of hybridization of one s-orbital and two p-orbitals, three hybrid sp 2 orbitals are formed, located in the same plane at an angle of 120° to each other. This is, for example, the configuration of the BF 3 molecule:

Fig.4 sp 2 hybridization

sp 3 hybridization

sp 3 hybridization is characteristic of carbon compounds. As a result of hybridization of one s-orbital and three

p-orbitals, four hybrid sp 3 -orbitals are formed, directed to the vertices of the tetrahedron with an angle between the orbitals of 109.5 o. Hybridization manifests itself in the complete equivalence of the bonds of the carbon atom with other atoms in compounds, for example, in CH 4, CCl 4, C (CH 3) 4, etc.

Fig.5 sp 3 hybridization

If all hybrid orbitals are bound to the same atoms, then the bonds are no different from each other. In other cases, small deviations from standard bond angles occur. For example, in a water molecule H 2 O oxygen - sp 3 -hybrid, is located in the center of an irregular tetrahedron, at the vertices of which two hydrogen atoms and two lone pairs of electrons "look" (Fig. 2). The shape of the molecule is angular, if you look at the centers of the atoms. The bond angle of HOH is 105°, which is quite close to the theoretical value of 109°.

Fig.6 sp 3 hybridization of oxygen and nitrogen atoms in molecules a) H 2 O and b) NCl 3.

If there was no hybridization (“alignment” O-H bonds), the HOH bond angle would be 90° because the hydrogen atoms would be attached to two mutually perpendicular p orbitals. In this case, our world would probably look completely different.

The hybridization theory explains the geometry of the ammonia molecule. As a result of hybridization of 2s and three 2p nitrogen orbitals, four sp 3 hybrid orbitals are formed. The configuration of the molecule is a distorted tetrahedron, in which three hybrid orbitals participate in the formation chemical bond, and the fourth with a pair of electrons does not. angles between N-H bonds not equal to 90 o as in a pyramid, but not equal to 109.5 o, corresponding to a tetrahedron.

Fig.7 sp 3 - hybridization in the ammonia molecule

When ammonia interacts with a hydrogen ion, an ammonium ion is formed as a result of the donor-acceptor interaction, the configuration of which is a tetrahedron.

Hybridization also explains the difference in the angle between O-H bonds in a corner water molecule. As a result of hybridization of 2s and three 2p oxygen orbitals, four sp 3 hybrid orbitals are formed, of which only two participate in the formation of a chemical bond, which leads to a distortion of the angle corresponding to the tetrahedron.

Fig.8 sp 3 hybridization in a water molecule

Hybridization can include not only s- and p-, but also d- and f-orbitals.

With sp 3 d 2 hybridization, 6 equivalent clouds are formed. It is observed in compounds such as 4-, 4-. In this case, the molecule has the configuration of an octahedron:

Rice. nine d 2 sp 3 -hybridization in ion 4-

Ideas about hybridization make it possible to understand such features of the structure of molecules that cannot be explained in any other way.

The hybridization of atomic orbitals (AO) leads to a shift of the electron cloud in the direction of bond formation with other atoms. As a result, the overlapping regions of hybrid orbitals turn out to be larger than for pure orbitals, and the bond strength increases.

Atomic orbital hybridization is the process of understanding how atoms change their orbitals when they form compounds. So, what is hybridization, and what types of it exist?

General characteristics of hybridization of atomic orbitals

Atomic orbital hybridization is a process in which different orbitals of the central atom are mixed, resulting in the formation of orbitals of the same characteristics.

Hybridization occurs during the formation of a covalent bond.

The hybrid orbital has the form of an infinity sign or an asymmetric inverted figure eight, extended away from the atomic nucleus. This form causes a stronger overlap of hybrid orbitals with orbitals (pure or hybrid) of other atoms than in the case of pure atomic orbitals and leads to the formation of stronger covalent bonds.

Rice. 1. Hybrid orbital appearance.

For the first time, the idea of hybridization of atomic orbitals was put forward by the American scientist L. Pauling. He believed that an atom entering into a chemical bond has different atomic orbitals (s-, p-, d-, f-orbitals), then hybridization of these orbitals occurs as a result. The essence of the process is that atomic orbitals equivalent to each other are formed from different orbitals.

Types of hybridization of atomic orbitals

There are several types of hybridization:

. This type of hybridization occurs when one s-orbital and one p-orbital mix. As a result, two full-fledged sp-orbitals are formed. These orbitals are located atomic nucleus so that the angle between them is 180 degrees.

Rice. 2. sp hybridization.

sp2 hybridization. This type of hybridization occurs when one s-orbital and two p-orbitals mix. As a result, three hybrid orbitals are formed, which are located in the same plane at an angle of 120 degrees to each other.
. This type of hybridization occurs when one s-orbital and three p-orbitals mix. As a result, four full-fledged sp3 orbitals are formed. These orbitals are directed to the top of the tetrahedron and are located at an angle of 109.28 degrees to each other.

sp3 hybridization is characteristic of many elements, for example, the carbon atom and other group IVA substances (CH 4, SiH 4, SiF 4, GeH 4, etc.)

Rice. 3. sp3 hybridization.

There are also more complex types hybridization involving d-orbitals of atoms.

What have we learned?

Hybridization is complex chemical process when different orbitals of an atom form the same (equivalent) hybrid orbitals. The first to voice the theory of hybridization was the American L. Pauling. There are three main types of hybridization: sp hybridization, sp2 hybridization, sp3 hybridization. There are also more complex types of hybridization that involve d-orbitals.

HYBRIDIZATION- this is the phenomenon of interaction between molecular orbitals that are close in energy and have common symmetry elements, with the formation of hybrid orbitals with lower energy.

The more completely in space the electron clouds involved in chemical bonding overlap with each other, the less energy the electrons that are in the overlapping region and carry out the bond have, and the stronger the chemical bond between these atoms.

Sometimes the bonds between atoms are stronger than expected from calculations. It is assumed that the atomic orbital takes a shape that allows it to more fully overlap with the orbital of the neighboring atom. An atomic orbital can change its shape only by combining with other atomic orbitals of a different symmetry of the same atom. As a result of the combination of different orbitals (s, p, d), new atomic orbitals of an intermediate form arise, which are called hybrid .

The rearrangement of various atomic orbitals into new orbitals averaged in shape is called hybridization .

The number of hybrid orbitals is equal to the number of original ones. So, with a combination of s- and p-orbitals (sp-hybridization), two hybrid orbitals arise, which are oriented at an angle of 180 ° to each other, Fig. 3, Table. 5 and 6.

(s+p) orbitals Two sp - orbitals Two sp-hybrid

orbitals

Figure 3 - sp - Hybridization of valence orbitals

Table 6 - Formation of hybrid orbitals

Table 7 - Formation of some molecules of V and VI periods

The chemical bond formed by the electrons of hybrid orbitals is stronger than the bond involving the electrons of non-hybrid orbitals, since during hybridization the overlap occurs in more. Hybrid orbitals form only s-bonds.

Orbitals that have close energies can undergo hybridization. For atoms with a small nuclear charge, only s- and p-orbitals are suitable for hybridization. This is most characteristic of the elements of the second period of groups II - VI, Table. 6 and 7.

In groups from top to bottom with an increase in the radius of the atom, the ability to form covalent bonds weakens, the difference in the energies of s- and p-electrons increases, the possibility of their hybridization decreases.

The electronic orbitals involved in the formation of bonds and their spatial orientation determine the geometric shape of the molecules.

Linear shape of molecules. Compounds that have a linear molecular shape are formed by overlapping:

1. Two s-orbitals (s - s bond): H 2, Na 2, K 2, etc.

2. s - and p-orbitals (s - p bond): HC1, HBr, etc.

3. Two p-orbitals (p - p bond): F 2, C1 2, Br 2, etc.

s–s s–p p–p

Figure 4 - Linear molecules

The linear form of the molecules is also formed by the atoms of some elements of group II with hydrogen or halogen atoms (BeH 2, BeG 2, ZnG 2). Let us consider the formation of BeCl 2 molecules. An atom of beryllium in an excited state has two unpaired electrons (2s l and 2p 1), therefore, sp-hybridization occurs, in which two sp-hybrid orbitals are formed, located at an angle of 180 ° relative to each other (see orbital hybridization). When beryllium interacts with halogens, two sp-hybrid orbitals of the beryllium atom overlap with the p-orbitals of two chlorine atoms, resulting in a linear molecule, Fig. 5.

Figure 5 - Linear BeCl 2 molecule

triangular shape of molecules takes place in the formation of boron and aluminum halides. The excited atom of the bot has three unpaired electrons (2s 1 and 2p 2). When chemical bonds are formed, sp 2 hybridization occurs and three sp 2 hybrid orbitals are formed, which lie in the same plane and are oriented to each other at an angle of 120 °, Fig. 6.

(s + p + p) - three sp 2 - hybrid

orbitals orbitals

Figure 6 - sp 2 -Hybridization of valence orbitals (a) and

triangular molecule BCl 3 (b)

When boron interacts with chlorine, three sp 2 hybrid orbitals of the boron atom overlap with the p orbitals of three chlorine atoms, resulting in a molecule that has the shape of a flat triangle. The bond angle in the BCl 3 molecule is 120°.

Tetrahedral shape of the molecule characteristic of compounds of elements of group IV main subgroup with halogens, hydrogen. So, the carbon atom in the excited state has four unpaired electrons (2s 1 and 2p 3), therefore, sp-hybridization occurs, during which four hybrid orbitals are formed, located at an angle of 109.28 ° to each other, Fig. 7.

(s + p + p + p) - four sp 3 -hybrid

orbitals orbitals

Figure 7 - sp 3 -Hybridization of valence orbitals (a) and

tetrahedral CH 4 molecule (b)

When four sp 3 hybrid orbitals of a carbon atom and s orbitals of four hydrogen atoms overlap, a methane molecule is formed, which has the shape of a tetrahedron. The bond angle is 109.28°.

Considered geometric shapes molecules (linear, triangular, tetrahedral) are ideal(Gillespie's rule).

In contrast to the compounds considered above, the molecules of elements of groups V and VI of the main subgroups have valence lone pairs of electrons, so the angles between bonds turn out to be smaller compared to ideal molecules.

Pyramidal shape of molecules takes place in the formation hydrogen compounds elements of V groups of the main subgroup. When a chemical bond is formed, for example, at the nitrogen atom, as well as at the carbon atom, sp 3 hybridization occurs and four sp 3 hybrid orbitals are formed, which are oriented at an angle of 109.28 about to each other. But unlike the carbon atom at the nitrogen atom, not only one-electron orbitals take part in hybridization(2p 3), but also two-electron(2s 2). Therefore, out of four sp 3 hybrid orbitals, three have one electron each (one-electron orbital), these orbitals form bonds with three hydrogen atoms. The fourth orbital with a non-sharing pair of electrons does not take part in bond formation. The NH 3 molecule has the shape of a pyramid, fig. eight.

Figure 8 - Pyramidal ammonia molecule

At the top of the pyramid is a nitrogen atom, and at the corners (triangle) of the base are hydrogen atoms. The bond angle is 107.3°. The deviation of the angle from tetrahedral (109.28°) is due to the repulsion between the lone pair of electrons in the fourth sp 3 hybrid orbital and the bonding pairs in the other three orbitals, i.e. The sp 3 hybrid orbital with a lone pair of electrons repels the other three orbitals of the N–H bond away from itself, reducing the angle to 107.3°.

In accordance with the Gillespie rule: if the central atom belongs to the elements of the third or subsequent periods, and the terminal atoms belong to less electronegative elements than halogens, then the formation of bonds is carried out through pure p orbitals and the bond angles become » 90 °, therefore, for nitrogen analogs (P, As, Sb) hybridization of orbitals in the molecules of hydrogen compounds is not observed. For example, three unpaired p-electrons (3s 2 and 3p 3), whose electronic orbitals are located in three mutually perpendicular directions, and s-electrons of three hydrogen atoms participate in the formation of a phosphine molecule (PH 3). The bonds are located along the three axes of p-orbitals. The resulting molecules, like the NH 3 molecules, have a pyramidal shape, but unlike the NH 3 molecule, in the PH 3 molecule the bond angle is 93.3 °, and in the AsH 3 and SbH 3 compounds, respectively 91.8 and 91.3 °, fig. 9 and tab. 4.

Figure 9 - Molecule PH 3

The lone pair of electrons will occupy the nonbonding s orbital.

Angular shape of molecules form hydrogen compounds of elements of group VI of the main subgroup. The considered features of bond formation in compounds of group V elements are also characteristic of hydrogen compounds of group VI elements. So, in a water molecule, the oxygen atom, like the nitrogen atom, is in the state of sp 3 hybridization. Of the four sp 3 hybrid orbitals, two have one electron each; these orbitals form bonds with two hydrogen atoms.

The other two of the four sp 3 hybrid orbitals each contain a lone pair of electrons and do not take part in bond formation.

The H 2 O molecule has an angular shape, the bond angle is 104.5°. The deviation of the angle value from the tetrahedral one is to an even greater extent due to repulsion from two lone pairs of electrons, Fig. ten.

Figure 10 - Angular water molecule

H 2 S, H 2 Se, H 2 Te have an angular shape of molecules, only analogues of oxygen, the formation of bonds in the connected H 2 E is carried out through pure p-orbitals(Gillespie's rule), so the bond angles are »90°. So, in H 2 S, H 2 Se, H 2 Te molecules, they are respectively equal to 92; 91; 89.5°.

Table 8 - Molecules of hydrogen compounds of elements of the 2nd period