In nature, substances occur in three states: solid, liquid and gaseous. For example, water can be in a solid (ice), liquid (water) and gaseous (water vapor) state. In the thermometer you are familiar with, mercury is a liquid. There are mercury vapors above the surface, and at a temperature of -39 C, mercury turns into a solid.

IN various states substances have different properties. Most of the bodies around us are made of solids. These are houses, cars, tools, etc. The shape of a solid body can be changed, but this requires effort. For example, to bend a nail, you need to apply quite a lot of force.

Under normal conditions, it is difficult to compress or stretch a solid body.

To give solids the desired shape and volume in plants and factories, they are processed on special machines: lathes, planers, and grinders.

A solid has its own shape and volume.

Unlike solids liquids easily change their shape. They take the shape of the vessel in which they are located.

For example, the milk that fills a bottle is shaped like a bottle. When poured into a glass, it takes the shape of a glass (Fig. 13). But, changing shape, the liquid retains its volume.

Under normal conditions, only small droplets of liquid have their own shape - the shape of a ball. These are, for example, raindrops or drops into which a stream of liquid breaks up.

The production of objects from molten glass is based on the property of a liquid to easily change its shape (Fig. 14).

Liquids easily change their shape but retain their volume.

The air we breathe is a gaseous substance, or gas. Since most gases are colorless and transparent, they are invisible.

The presence of air can be felt when standing at the open window of a moving train. Its presence in the surrounding space can be felt if there is a draft in the room, and can also be proven using simple experiments.

If you turn a glass upside down and try to lower it into water, the water will not enter the glass because it is filled with air. Now let’s lower a funnel into the water, which is connected by a rubber hose to a glass tube (Fig. 15). The air from the funnel will begin to escape through this tube.

These and many other examples and experiments confirm that there is air in the surrounding space.

Gases, unlike liquids, easily change their volume. When we squeeze a tennis ball, we change the volume of air filling the ball. A gas placed in a closed container occupies the entire container. You cannot fill half a bottle with gas the way you can with liquid.

Gases do not have their own shape and constant volume. They take the shape of the vessel and completely fill the volume provided to them.

1. What three states of matter do you know? 2. List the properties of solids. 3. Name the properties of liquids. 4. What properties do gases have?

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Age: 3rd grade.

Subject: Bodies, substances, particles.

Lesson type: learning new material.

Lesson duration: 45 minutes.

Lesson objectives: form the concept of body, substance, particle, teach to distinguish substances according to their characteristics and properties.

Tasks:

• Introduce children to the concepts of body, matter, particle.
• Teach to distinguish substances in different states of aggregation.
• Develop memory and thinking.
• Improve self-esteem and self-control skills.
• Increase the psychological comfort of the lesson, relieve muscle tension ( dynamic pauses, change of activity).
• Shape friendly relations a team.
• Cultivate interest in the world around you.

Equipment:

1. Multimedia interactive presentation (Annex 1). Presentation control Appendix 2.

2. Drawings (solid, liquid, gaseous substances).

3. Metal ruler, rubber ball, wooden cube (from the teacher).

4. For the experiment: glass, teaspoon, piece of sugar; boiled water(on children's tables).

During the classes

I. Organizational moment.

The teacher welcomes the children, checks their readiness for the lesson, addressing the students: “Today you will complete all tasks in groups. Let’s repeat the rules of working in a group” (slide No. 2).

1. Treatment of comrades – “politeness”;
2. Opinion of others - “learn to listen, prove your point of view”;
3. Working with sources of information (dictionary, book) - highlight the main thing.

II. Learning new material.

Staging educational goal: today we begin to study the topic “This amazing nature” - let’s take a virtual tour (slide No. 3). On the slide: a drop of water, a sugar bowl (storage container), a hammer, a wave (water), clay, metal.

The teacher asks the question “Did all the words allow you to accurately represent the subject?”

Those words that accurately help to represent an object, namely, have an outline, a shape, are called bodies. What these objects are made of are called substances.

Working with a source of information (dictionary by S.I. Ozhegov):

Write down the definition in your notebook: “Those objects that surround us are called bodies”(slide number 4).

Slide No. 5. The teacher invites students to compare the pictures located on the slide: a rubber ball, an envelope, a wooden cube.

Task 1: find the commonality. All bodies have size, shape, etc.

Task 2: identify the main characteristics of bodies. Answer on slide number 6: control button “answer 2”.

Slide number 6. Pictures are triggers. The ball is round, rubber, bright. Envelope – rectangular, paper, white. The cube is wooden, large, beige.

Together with the guys we conclude: “Every body has a size, shape, color.” We write it down in a notebook.

Slide number 7. What is nature? Choose the correct answer from three answer options:

Slide number 8 – working with cards. Students have cards with pictures of bodies (objects) on their desks. We invite students to divide the cards into two groups: table, sun, tree, pencil, cloud, stone, books, chair. Let's write down the answers in our notebooks. We ask students to read the names of the bodies, this will be 1 group. On what basis did they place the words in this group? We do the same with the second group.

Correct answer:

We draw a conclusion. How we divided the words (by what principle?): There are bodies that are created by nature, and there are those that are created by human hands.

We draw up the block in a notebook (Figure 1).

Slide number 9. “Interactive feed” technique. The slide shows natural and artificial bodies. Using the scroll button, which is also a trigger, we look through natural and artificial bodies (each time you press the button, the grouped pictures change).

We consolidate the acquired knowledge with the help of the game “Traffic Light” (slides 10-12). The game is about finding the correct answer.

Slide 10. Task: find natural bodies. From the proposed bodies on the slide, you must select only natural bodies. The picture is a trigger - when pressed, a traffic light signal (red or green) appears. Sound files help students ensure they have chosen the correct answer.

Teacher. Let us remember what we talked about at the beginning. We found it difficult to accurately determine whether metal, water, and clay are bodies and came to the conclusion that they do not have exact outlines or shapes, and therefore are not bodies. We call these words substances. All bodies are made of substances. Write down the definition in your notebook.

Slide 13. On this slide we will look at two examples.

Example 1: scissors - body, what they are made of - substance (iron).

Example 2: drops of water are bodies, the substance of which the drops are made is water.

Slide number 14. Let's consider bodies that consist of several substances. For example, a pencil and a magnifying glass. On the slide we look separately at the substances that make up a pencil. To demonstrate, click on the control buttons: “graphite”, “rubber”, “wood”. In order to remove unnecessary information, press the cross.

Let's consider what substances the magnifying glass consists of. Press the triggers “glass”, “wood”, “metal”.

Slide No. 15. To reinforce this, let’s look at two more examples. What is a hammer made of? The hammer consists of iron and wood (handle). What are knives made of? Knives are composed of iron and wood substances.

Slide number 16. Consider two objects that consist of several substances. Meat grinder: made of iron and wood. Sled: made of iron and wood.

Slide 17. We conclude: bodies can consist of one substance, or they can consist of several.

Slides 18, 19, 20. “Interactive feed” technique. We show it to the students. One substance can be part of several bodies.

Slide 18. Substances consist entirely or partially of glass.

Slide 19. Substances consist entirely or partially of metal.

Slide 20. Substances consist entirely or partially of plastic.

Slide 21. The teacher asks the question “Are all substances the same?”

On the slide, click the “Start” control button. Notebook entry: all substances consist of tiny invisible particles. We introduce a classification of substances according to their state of aggregation: liquid, solid, gaseous. The slide uses triggers (arrows). When you click on the arrow, you can see a picture of particles in a given state of aggregation. Click on the arrow again and the objects will disappear.

Slide 22. Experimental part. It is necessary to prove that the particles are tiny, invisible to the eye, but retaining the properties of the substance.

Let's do an experiment. On the students' tables are trays with a set of simple laboratory equipment: a glass, a spoon for stirring, a napkin, a piece of sugar.

Place a piece of sugar in a glass and stir until completely dissolved. What are we seeing? The solution has become homogeneous, we no longer see a piece of sugar in a glass of water. Prove that there is still sugar in the glass. How? To taste. Sugar: substance white, sweet taste. Conclusion: after dissolution, sugar did not cease to be sugar, because it remained sweet. This means that sugar consists of tiny particles invisible to the eye (molecules).

Slide 23. Let's consider the arrangement of particles in substances with a solid state of aggregation. We demonstrate the location of particles and matter (examples) using the “interactive tape” technique - the scroll button allows you to show the pictures the required number of times. We write down the conclusion in our notebook: in solids, particles are located close to each other.

Slide 24. Arrangement of particles in liquid substances. In liquid substances, particles are located at some distance from each other.

Slide No. 25. The arrangement of particles in gaseous substances: the particles are located far from each other, the distance between them significantly exceeds the particle size itself.

Slide 31. It's time to summarize. Together with the teacher, they remember what they learned new in the lesson. The teacher asks questions:

1. Everything that surrounds us is called... bodies
2. There are bodies natural And artificial.
3. Write down the diagram in your notebook. Teacher: Let's look at the diagram. Bodies can be natural and artificial, substances can be solid, liquid, gaseous. Substances are made up of particles.

The particle retains the properties of the substance (remember that sugar remained sweet when dissolved). The slide uses triggers. Click on the “Body” shape, arrows appear, then shapes labeled “Artificial” and “Natural”.

When you click on the “substance” figure, three arrows appear (liquid, solid, gaseous). + Slide number 30. Fill out the table. Read the instructions carefully.

(Mark with “	” in the corresponding column, which of the listed substances are solid, liquid, gaseous).	Substance	Solid
Liquid
Gaseous
Salt
Natural gas
Sugar
Water
Aluminum
Alcohol

Iron

Carbon dioxide

Checking the progress of the work (slide 30). Children take turns naming the substance and explaining which group it belongs to.

Lesson summary

Let's find out which group was the most attentive in the lesson. The teacher asks the question: “What are called bodies, what characterizes a body, give an example.” Students answer. Everything that surrounds us is called bodies. What are the types of substances based on their state of aggregation: liquid, solid, gaseous. What do substances consist of? Give examples of how particles retain the properties of substances. For example, if we add salt to soup, how do we know that the properties of the substance have been preserved? To taste. Fill out the diagram (Figure 2)

Discussion: what we agree with, what we disagree with.

What new did you learn? Children report. ( All objects surrounding us are called bodies. Bodies are made up of substances. Substances are made from particles).

Homework

The teacher tells the children homework(optional):

• solve a small test (Appendix 5).
• interactive test (Appendix 3).
• view presentation about water (Appendix 7). In the presentation you can get acquainted with six known facts
• about water. Think, guys, why do you need to get to know this substance better? Answer: the most abundant substance on Earth. What other substance would you like to invite to your place (creating virtual excursions). study the electronic textbook

(Appendix 4).

Note: the teacher can additionally use slides No. 32, 33, 36.

Slide number 32. Task: test yourself. Find products (interactive test).

Slide number 33. Task: test yourself. Find living and inanimate bodies (interactive test).

Slide No. 36. Task: divide bodies into bodies of animate and inanimate nature (interactive test).

1. Literature.
2. Gribov P.D. how a person explores, studies, uses nature. 2-3 grades. Volgograd: Teacher, 2004.-64 p. Maksimova T.N. Lesson developments for the course “ The world
3. ”: 2nd grade. - M.: VAKO, 2012.-336 p. - (To help the school teacher).
4. Reshetnikova G.N., Strelnikov N.I. The world. Grade 3: entertaining materials. - Volgograd: Teacher, 2008. - 264 pp.: ill.

Find

Gaseous state of matter

Just as in the case of ordinary molecules, a system of macromolecules. forming a polymer tends to the most probable state - stable equilibrium, corresponding to a minimum of free energy. Therefore, in principle, polymers should also have a crystal lattice structure. However, due to the bulk and complexity of macromolecules, only in a few cases it was possible to obtain perfect macromolecular crystals. In most cases, polymers consist of crystalline and amorphous regions.

Liquid state characterized by the fact that the potential energy of attraction of molecules is slightly higher than absolute value their kinetic energy. The force of attraction between molecules in a liquid ensures that the molecules are held in the volume of the liquid. At the same time, the molecules in a liquid are not connected to each other by stationary stable bonds, as in crystals. They tightly fill the space occupied by the liquid, so liquids are practically incompressible and have sufficient high density. Groups of molecules can change their relative position, which ensures the fluidity of liquids. The property of a liquid to resist flow is called viscosity. Liquids are characterized by diffusion and Brownian motion, but significantly to a lesser extent than gases.

The volume occupied by a liquid is limited by the surface. Since, for a given volume, a sphere has the minimum surface area, the liquid in a free state (for example, in weightlessness) takes the shape of a sphere.

Liquids have some structure, which, however, is much less pronounced than that of solids. The most important property of liquids is isotropy of properties. A simple ideal fluid model has not yet been created.

There is an intermediate state between liquids and crystals, which is called liquid crystalline. A feature of liquid crystals from a molecular point of view is the elongated, spindle-shaped shape of their molecules, which leads to anisotropy of their properties.

There are two types of liquid crystals - nematics and smectics. Smectics are characterized by the presence of parallel layers of molecules that differ from each other in the order of their structure. In nematics, order is ensured by the orientation of molecules. The anisotropy of the properties of liquid crystals determines their important optical properties. Liquid crystals can, for example, be transparent in one direction and opaque in another. It is important that the orientation of liquid crystal molecules and their layers can be easily controlled using external influences(eg temperature, electric and magnetic fields).

Gaseous state of matter occurs when

kinetic energy thermal movement molecules exceeds the potential energy of their binding. The molecules tend to move away from each other. The gas has no structure, occupies the entire volume provided to it, and is easily compressed; Diffusion occurs easily in gases.

The properties of substances in a gaseous state are explained by the kinetic gas theory. Its main postulates are as follows:

All gases are made up of molecules;

The sizes of molecules are negligible compared to the distances between them;

Molecules are constantly in a state of chaotic (Brownian) motion;

Between collisions, molecules retain constant speed movements; trajectories between collisions are straight line segments;

The collision between molecules and molecules with the walls of the vessel are ideally elastic, i.e. the total kinetic energy of the colliding molecules remains unchanged.

Let us consider a simplified model of a gas that obeys the above postulates. Such a gas is called an ideal gas. Let an ideal gas consist of N identical molecules, each of which has a mass m, is in a cubic vessel with an edge length l(Fig. 5.14). Molecules move chaotically; their average speed<v>. To simplify, let us divide all the molecules into three equal groups and assume that they move only in directions perpendicular to the two opposite walls of the vessel (Fig. 5.15).

Rice. 5.14.

Each gas molecule moving at a speed<v> in case of an absolutely elastic collision with the wall of the vessel, it will change the direction of movement to the opposite without changing the speed. Molecular Momentum<R> = m<v> becomes equal to - m<v>. The change in momentum in each collision is obviously . The force acting during this collision is equal to F= -2m<v>/Δ t. Complete change in momentum upon collision with the walls of all N/3 molecules equals . Let's define the time interval Δ t, during which all N/3 collisions will occur: D t = 2//< v >. Then the average value of the force acting on any wall is

Pressure R define the gas on the wall as the force ratio<F> to the wall area l 2:

Where V = l 3 – volume of the vessel.

Thus, the pressure of a gas is inversely proportional to its volume (recall that this law was empirically established by Boyle and Marriott).

Let us rewrite expression (5.4) in the form

Here is the average kinetic energy of gas molecules. it is proportional absolute temperature T:

Where k– Boltzmann constant.

Substituting (5.6) into (5.5), we obtain

It is convenient to go from the number of molecules N to the number of moles n gas, we recall that ( N A is Avogadro’s number), and then

Where R = kN A - is the universal gas constant.

Expression (5.8) is the equation of state of a classical ideal gas for n moles. This equation, written for an arbitrary mass m gas

Where M - molar mass gas, is called the Clapeyron-Mendeleev equation (see (5.3)).

Real gases obey this equation to a limited extent. The fact is that equations (5.8) and (5.9) do not take into account the intermolecular interaction in real gases - van der Waals forces.

Phase transitions. A substance, depending on the conditions in which it is located, can change its state of aggregation, or, as they say, move from one phase to another. This transition is called a phase transition.

As stated above, the most important factor, which determines the state of a substance is its temperature T, characterizing the average kinetic energy of thermal motion of molecules and pressure R. Therefore, states of matter and phase transitions are analyzed using a state diagram, where the values ​​are plotted along the axes T And R, and each point on the coordinate plane determines the state of a given substance corresponding to these parameters. Let's analyze a typical diagram (Fig. 5.16). Curves OA, AB, AK separate states of matter. When enough low temperatures Almost all substances are in a solid crystalline state.

The diagram highlights two characteristic points: A And TO. Dot A called triple point; at appropriate temperatures ( T t) and pressure ( R r) it contains gas, liquid and solid at the same time.

Dot TO indicates a critical condition. At this point (at T cr and R cr) the difference between liquid and gas disappears, i.e. the latter have the same physical properties.

Curve OA is a sublimation (sublimation) curve; at appropriate pressure and temperature, a gas-solid transition (solid-gas) occurs, bypassing the liquid state.

Under pressure R T< R < R The transition from the gaseous to the solid state (and vice versa) can only occur through the liquid phase.

Curve AK corresponds to evaporation (condensation). At appropriate pressure and temperature, the transition “liquid - gas” (and vice versa) occurs.

Curve AB is the liquid-solid transition curve (melting and crystallization). This curve has no end, since the liquid state always differs from the crystalline state in structure.

To illustrate, we present the shape of the surfaces of states of matter in variables p, v, t(Fig. 5.17), where V- volume of substance

The letters G, F, T indicate areas of surfaces whose points correspond to gaseous, liquid or solid states, and areas surfaces T-G, Zh-T, T-Zh - two-phase states. Obviously, if we project the dividing lines between the phases onto coordinate plane RT, we obtain a phase diagram (see Fig. 5.16).

Quantum liquid - helium. At ordinary temperatures in macroscopic bodies, due to pronounced chaotic thermal motion, quantum effects are imperceptible. However, with decreasing temperature, these effects can come to the fore and manifest themselves macroscopically. For example, crystals are characterized by the presence of thermal vibrations of ions located at the nodes of the crystal lattice. As the temperature decreases, the amplitude of the oscillations decreases, but even when approaching absolute zero, the oscillations, contrary to classical ideas, do not stop.

The explanation for this effect follows from the uncertainty relation. A decrease in the amplitude of oscillations means a decrease in the localization area of ​​the particle, i.e., the uncertainty of its coordinates. According to the uncertainty relation, this leads to an increase in the uncertainty of the momentum. Thus, the “stopping” of a particle is prohibited by the laws of quantum mechanics.

This purely quantum effect manifests itself in the existence of matter remaining in liquid state even at temperatures close to absolute zero. Such a “quantum” liquid is helium. The energy of zero-point vibrations is enough to destroy the crystal lattice. However, at a pressure of about 2.5 MPa, liquid helium still crystallizes.

Plasma. The imparting of significant energy to the atoms (molecules) of a gas from the outside leads to ionization, i.e., the disintegration of atoms into ions and free electrons. This state of matter is called plasma.

Ionization occurs, for example, when a gas is strongly heated, which leads to a significant increase in the kinetic energy of atoms, with electrical discharge in a gas (impact ionization by charged particles), when the gas is exposed to electromagnetic radiation (autoionization). Plasma obtained at ultra-high temperatures is called high-temperature.

Since ions and electrons in plasma carry uncompensated electric charges, their mutual influence essential. Between charged plasma particles there is not a pair interaction (as in a gas), but a collective interaction. Due to this, the plasma behaves as a kind of elastic medium, in which various vibrations and waves are easily excited and propagated

Plasma actively interacts with electric and magnetic fields. Plasma is the most common state of matter in the Universe. Stars consist of high-temperature plasma, cold nebulae - of low-temperature plasma. Weakly ionized low-temperature plasma exists in the Earth's ionosphere.

References for Chapter 5

1. Akhiezer A. I., Rekalo Ya. P. Elementary particles. - M.: Nauka, 1986.

2. Azshlov A. The world of carbon. - M.: Chemistry, 1978.

3. Bronshtein M.P. Atoms and electrons. - M.: Nauka, 1980.

4. Benilovsky V.D. These amazing liquid crystals. - M: Enlightenment, 1987.

5. Vlasov N. A. Antimatter. - M.: Atomizdat, 1966.

6. Christie R., Pitti A. Structure of matter: an introduction to modern physics. - M.: Nauka, 1969.

7. Krejci V. The world through the eyes modern physics. - M.: Mkr, 1984.

8. Nambu E. Quarks. - M.: Mir, 1984.

9. Okun L. B. α, β, γ, …,: an elementary introduction to the physics of elementary particles. - M.: Nauka, 1985.

10. Petrov Yu. I. Physics of small particles. - M.: Nauka, 1982.

11. I, Purmal A.P. et al. How substances are converted. - M.: Nauka, 1984.

12. Rosenthal I. M. Elementary particles and the structure of the universe. - M.: Nauka, 1984.

13. Smorodinsky Ya. A. Elementary particles. - M.: Knowledge, 1968.

Today, more than 3 million are known to exist. various substances. And this figure is growing every year, as synthetic chemists and other scientists are constantly conducting experiments to obtain new compounds that have some useful properties.

Some substances are natural inhabitants that form naturally. The other half are artificial and synthetic. However, in both the first and second cases, a significant part is made up of gaseous substances, examples and characteristics of which we will consider in this article.

Aggregate states of substances

Since the 17th century, it was generally accepted that all known compounds are capable of existing in three states of aggregation: solid, liquid, and gaseous substances. However, careful research of recent decades in the fields of astronomy, physics, chemistry, space biology and other sciences have proven that there is another form. This is plasma.

What is she? This is partially or completely. And it turns out that there is an overwhelming majority of such substances in the Universe. So, it is in the plasma state that the following are found:

• interstellar matter;
• cosmic matter;
• upper layers of the atmosphere;
• nebulae;
• composition of many planets;
• stars.

Therefore, today they say that there are solids, liquids, gases and plasma. By the way, every gas can be artificially transferred to this state if it is subjected to ionization, that is, forced to turn into ions.

Gaseous substances: examples

There are a lot of examples of the substances under consideration. After all, gases have been known since the 17th century, when Van Helmont, a natural scientist, first obtained carbon dioxide and began to explore its properties. By the way, he also gave the name to this group of compounds, since, in his opinion, gases are something disordered, chaotic, associated with spirits and something invisible, but tangible. This name has taken root in Russia.

It is possible to classify all gaseous substances, then it will be easier to give examples. After all, it is difficult to cover all the diversity.

According to the composition they are distinguished:

• simple,
• complex molecules.

The first group includes those that consist of identical atoms in any quantity. Example: oxygen - O 2, ozone - O 3, hydrogen - H 2, chlorine - CL 2, fluorine - F 2, nitrogen - N 2 and others.

• hydrogen sulfide - H 2 S;
• hydrogen chloride - HCL;
• methane - CH 4;
• sulfur dioxide - SO 2;
• brown gas - NO 2;
• freon - CF 2 CL 2;
• ammonia - NH 3 and others.

Classification by nature of substances

You can also classify the types of gaseous substances according to their belonging to the organic and inorganic world. That is, by the nature of the atoms that make up it. Organic gases are:

• the first five representatives (methane, ethane, propane, butane, pentane). General formula C n H 2n+2 ;
• ethylene - C 2 H 4;
• acetylene or ethylene - C 2 H 2;
• methylamine - CH 3 NH 2 and others.

Another classification that the compounds in question can be subjected to is division based on the particles they contain. Not all gaseous substances are made of atoms. Examples of structures containing ions, molecules, photons, electrons, Brownian particles, plasma, also refer to compounds in such a state of aggregation.

Properties of gases

The characteristics of substances in the state under consideration differ from those of solid or liquid compounds. The thing is that the properties of gaseous substances are special. Their particles are easily and quickly mobile, the substance as a whole is isotropic, that is, the properties are not determined by the direction of movement of the structures included in the composition.

It is possible to identify the most important physical properties of gaseous substances, which will distinguish them from all other forms of existence of matter.

1. These are connections that cannot be seen, controlled, or felt by ordinary human means. To understand the properties and identify a particular gas, they rely on four parameters that describe them all: pressure, temperature, amount of substance (mol), volume.
2. Unlike liquids, gases are capable of occupying the entire space without a trace, limited only by the size of the vessel or room.
3. All gases easily mix with each other, and these compounds do not have an interface.
4. There are lighter and heavier representatives, so under the influence of gravity and time, it is possible to see their separation.
5. Diffusion is one of the the most important properties these connections. The ability to penetrate other substances and saturate them from the inside, while performing completely disordered movements within its structure.
6. Real gases electricity cannot conduct, but if we talk about rarefied and ionized substances, then conductivity increases sharply.
7. The heat capacity and thermal conductivity of gases is low and varies among different species.
8. Viscosity increases with increasing pressure and temperature.
9. There are two options for interphase transition: evaporation - a liquid turns into vapor, sublimation - a solid substance, bypassing the liquid one, becomes gaseous.

A distinctive feature of vapors from true gases is that the former certain conditions are capable of turning into a liquid or solid phase, but the latter are not. It should also be noted that the compounds in question are able to resist deformation and be fluid.

Such properties of gaseous substances allow them to be widely used in the most various areas science and technology, industry and national economy. In addition, specific characteristics are strictly individual for each representative. We considered only the features common to all real structures.

Compressibility

At different temperatures, and also under the influence of pressure, gases are able to compress, increasing their concentration and reducing their occupied volume. At elevated temperatures they expand, at low temperatures they contract.

Changes also occur under pressure. The density of gaseous substances increases and, upon reaching a critical point, which is different for each representative, a transition to another state of aggregation may occur.

The main scientists who contributed to the development of the study of gases

There are many such people, because the study of gases is a labor-intensive and historically long process. Let's focus on the most famous personalities who managed to do the most significant discoveries.

1. made a discovery in 1811. It doesn’t matter what kind of gases, the main thing is that under the same conditions, one volume contains an equal amount of them in terms of the number of molecules. There is a calculated value named after the name of the scientist. It is equal to 6.03 * 10 23 molecules for 1 mole of any gas.
2. Fermi - created the theory of an ideal quantum gas.
3. Gay-Lussac, Boyle-Marriott - the names of the scientists who created the basic kinetic equations for calculations.
4. Robert Boyle.
5. John Dalton.
6. Jacques Charles and many other scientists.

Structure of gaseous substances

The most main feature in the construction of the crystal lattice of the substances under consideration, this is that in its nodes there are either atoms or molecules that are connected to each other by weak covalent bonds. Van der Waals interaction forces are also present when we're talking about about ions, electrons and other quantum systems.

Therefore, the main types of structure of gas lattices are:

• atomic;
• molecular.

The connections inside are easily broken, so these connections do not have a constant shape, but fill the entire spatial volume. This also explains the lack of electrical conductivity and poor thermal conductivity. But gases have good thermal insulation, because, thanks to diffusion, they are able to penetrate into solids and occupy free cluster spaces inside them. At the same time, air is not passed through, heat is retained. This is the basis for the combined use of gases and solids for construction purposes.

Simple substances among gases

We have already discussed above which gases belong to this category in terms of structure and structure. These are those that consist of identical atoms. Many examples can be given, because a significant part of non-metals from all periodic table under normal conditions it exists in precisely this state of aggregation. For example:

• white phosphorus - one of this element;
• nitrogen;
• oxygen;
• fluorine;
• chlorine;
• helium;
• neon;
• argon;
• krypton;
• xenon.

The molecules of these gases can be either monatomic (noble gases) or polyatomic (ozone - O 3). The type of bond is covalent nonpolar, in most cases it is quite weak, but not in all of them. Crystal cell molecular type, which allows these substances to easily transition from one state of aggregation to another. For example, iodine under normal conditions is dark purple crystals with a metallic luster. However, when heated, they sublimate into clouds of bright purple gas - I 2.

By the way, any substance, including metals, can exist in a gaseous state under certain conditions.

Complex compounds of gaseous nature

Such gases, of course, are the majority. Various combinations of atoms in molecules, united by covalent bonds and van der Waals interactions, allow the formation of hundreds of different representatives of the considered state of aggregation.

Examples namely complex substances among gases there can be all compounds consisting of two or more different elements. This may include:

• propane;
• butane;
• acetylene;
• ammonia;
• silane;
• phosphine;
• methane;
• carbon disulfide;
• sulphur dioxide;
• brown gas;
• freon;
• ethylene and others.

Crystal lattice of molecular type. Many of the representatives easily dissolve in water, forming the corresponding acids. Most of Such compounds are an important part of chemical syntheses carried out in industry.

Methane and its homologues

Sometimes general concept"gas" refers to a natural mineral that is a whole mixture gaseous products predominantly organic in nature. It contains substances such as:

• methane;
• ethane;
• propane;
• butane;
• ethylene;
• acetylene;
• pentane and some others.

In industry, they are very important, because the propane-butane mixture is the household gas with which people cook, which is used as a source of energy and heat.

Many of them are used for the synthesis of alcohols, aldehydes, acids and others organic matter. Annual consumption natural gas amounts to trillions of cubic meters, and this is quite justified.

Oxygen and carbon dioxide

What gaseous substances can be called the most widespread and known even to first-graders? The answer is obvious - oxygen and carbon dioxide. After all, they are the direct participants in the gas exchange that occurs in all living beings on the planet.

It is known that it is thanks to oxygen that life is possible, since only some species can exist without it. anaerobic bacteria. And carbon dioxide is required product"nutrition" for all plants that absorb it in order to carry out the process of photosynthesis.

From a chemical point of view, both oxygen and carbon dioxide are important substances for carrying out syntheses of compounds. The first is a strong oxidizing agent, the second is more often a reducing agent.

Halogens

This is a group of compounds in which atoms are particles gaseous substance, connected in pairs to each other by a covalent nonpolar bond. However, not all halogens are gases. Bromine is a liquid under ordinary conditions, and iodine is an easily sublimated solid. Fluorine and chlorine are toxic substances that are dangerous to the health of living beings, which are strong oxidizing agents and are used very widely in syntheses.

The world around us is a variety of objects and forms. But all the diversity of our world can be divided into three groups: bodies, substances and particles. How to distinguish them and what characterizes each of these concepts will be discussed in the lesson on the surrounding world in 3rd grade.

Bodies

From the point of view of science, any object is a body. Everything that surrounds you, at home, in the classroom, on the street, is bodies. For example, a mug, table, telephone, stone, chair, ball.

According to the origin of the body there can be:

• natural– created by nature;
• artificial– created by man;
• alive;
• non-living.

Rice. 1. Diversity of bodies

The body is characterized by:

• size;
• shape;
• color
• mass;
• temperature.

When divided, any body turns into a new object. For example, a handle is a body, but if you take it apart, you get several parts.

Substances

Substance is what the body is made of. An object may consist of several substances. For example, a jug is made of clay, a scarf is knitted of wool, a spoon is made of metal.

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Rice. 2. Substances

Substances come in three states:

• hard- those that can be touched;
• liquid– for example, water;
• gaseous- air.

One of amazing properties Some bodies are the ability to move from one state to another under the influence of certain factors. For example, water at temperatures below zero takes the solid form of ice, and at 100 degrees Celsius it begins to boil and turns into a gaseous form - steam.

Unlike the body, substances do not change during division. If a piece of sugar is divided into several more parts, then each of them will still be sugar. Or pour water into cups, it will remain water and will not become a new substance.

Particles

Substances are made up of even smaller units. They are so small that they cannot be seen without a microscope. They are called particles.

Particles retain the properties of matter. As an experiment, you can stir a piece of sugar in water. This will make the liquid sweet, but we will not see the substance, since the sugar particles are mixed with water particles.

There is free space between the particles. The state of a substance will depend on how densely the elements are contained in it. In solid substances there are almost no spaces between particles, in liquid substances there is some distance between the elements, and in gaseous substances the particles move freely because there is a large distance between them.

Rice. 3. Particles in different bodies

What have we learned?

The topic “Bodies, substances, particles” on the surrounding world is a very interesting subject for discussion. Many experiments can be done to study their properties. Bodies are complex objects consisting of one or more substances. In turn, in any material there is a collection of the smallest indivisible elements - particles.