In nature, substances are found 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 at special machines: turning, planing, grinding.

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 tennis ball, then 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?

Gaseous substances.

Lecture No. 12

Subject:"Drugs acting on the central nervous system."

1. Anesthesia.

2. Ethyl alcohol.

3. Sleeping pills

4. Antiepileptic drugs.

5. Antiparkinsonian drugs

6. Analgesics.

Drugs affecting the central nervous system

Anesthetic agents.

These include substances that cause surgical anesthesia. Narcosis is a reversible depression of central nervous system functions, which is accompanied by loss of consciousness, loss of sensitivity, decreased reflex excitability and muscle tone.

Anesthetics inhibit transmission nerve impulses at the synapses of the central nervous system. CNS synapses have unequal sensitivity to drugs. This explains the presence of stages in the action of anesthesia.

Stages of anesthesia:

1. stage of analgesia (stunning)

2. stage of excitement

3. stage of surgical anesthesia

Level 1 – superficial anesthesia

Level 2 light anesthesia

Level 3 deep anesthesia

Level 4 ultra-deep anesthesia

4. stage of awakening or agonal.

Depending on the route of administration, they distinguish between inhaled and non-inhaled narcotic drugs.

Inhaled drugs.

Enter through respiratory tract.

These include:

1. Volatile liquids - ether for anesthesia, fluorothan (halothane), chloroethyl, enflurane, isoflurane, sevoflurane.

2. gaseous substances– nitrous oxide, cyclopropane, ethylene.

This is an easily administered anesthesia.

Volatile liquids.

Ether for anesthesia– colorless, transparent, volatile liquid, explosive. Highly active. Irritates the mucous membrane of the upper respiratory tract, depresses breathing.

Stages of anesthesia.

Stage 1 – stunning (analgesia). Synapses of the reticular formation are inhibited. Main sign – confusion, decreased pain sensitivity, impaired conditioned reflexes, unconditional preserved, breathing, pulse, blood pressure are almost unchanged. At this stage, short-term operations can be performed (opening an abscess, phlegmon, etc.).

Stage 2 – excitement. The synapses of the cerebral cortex are inhibited. The inhibitory influences of the cortex on the subcortical centers are activated, and excitation processes predominate (the subcortex is disinhibited). “Revolt of the subcortex.” Consciousness is lost, motor and speech excitation (singing, swearing), muscle tone increases (patients are tied up). Intensifying unconditioned reflexes– cough, vomiting. Breathing and pulse are increased, blood pressure is increased.

Complications: reflex cessation of breathing, secondary cessation of breathing: spasm of the glottis, retraction of the tongue, aspiration of vomit. This stage of ether is very pronounced. It is impossible to operate at this stage.

Stage 3 – surgical anesthesia. Inhibition of synapses spinal cord. Unconditioned reflexes are inhibited and muscle tone decreases.

The operation begins at level 2 and is performed at level 3. The pupils will be slightly dilated, almost unresponsive to light, tone skeletal muscles sharply reduced, blood pressure decreases, pulse is faster, breathing is less, rare and deep.

If the dosage of a drug is incorrect, an overdose may occur. And then level 4 ultra-deep anesthesia develops. The synapses of the centers of the medulla oblongata - respiratory and vasomotor - are inhibited. The pupils are wide and do not respond to light, breathing is shallow, pulse is fast, blood pressure is low.

When breathing stops, the heart may still beat for some time. Resuscitation begins, because There is a sharp depression of breathing and blood circulation. Therefore, anesthesia must be maintained at stage 3, level 3, and not brought to level 4. Otherwise, the agonal stage develops. With the correct dosage of narcotic substances and stopping their administration, it develops Stage 4 – awakening. Restoration of functions proceeds in the reverse order.

With ether anesthesia, awakening occurs within 20-40 minutes. Awakening is replaced by a long post-anesthesia sleep.

During anesthesia, the patient's body temperature decreases and metabolism is inhibited. Heat production is reduced . Complications that may occur after ether anesthesia include: pneumonia, bronchitis (ether, irritates the respiratory tract), degeneration of parenchymal organs (liver, kidneys), reflex respiratory arrest, cardiac arrhythmias, damage to the conduction system of the heart.

Ftorotan – (halothane) – colorless, transparent, volatile liquid. Non-flammable. Stronger than ether. Does not irritate mucous membranes. The arousal stage is shorter, awakening is faster, sleep is shorter. Side effect – dilates blood vessels, reduces blood pressure, causes bradycardia (atropine is administered to prevent it).

Chloroethyl– stronger than ether, causes easily controlled anesthesia. Comes quickly and goes quickly. Flaw– small breadth of narcotic action. Has a toxic effect on the heart and liver. Used for Rausch anesthesia(short anesthesia for opening phlegmons, abscesses). Widely used for local anesthesia, applied to the skin. Boils at body temperature. Cools tissues, reduces pain sensitivity. Apply for superficial pain relief during surgical operations, myositis, neuralgia, sprained ligaments and muscles. Do not overcool tissues, because there may be necrosis.

Gaseous substances.

Nitrous oxide- laughing gas.

Available in pressurized cylinders. Used in a mixture with O 2. A weak narcotic substance. Combine with others narcotic substances– ether, substances for intravenous anesthesia.

Anesthesia occurs quickly, without the stage of excitement. Quickly awakens. Superficial anesthesia. Side effects No. Apply for injuries, myocardial infarction, transportation of patients, surgical interventions.

Cyclopropane– gas. 6 times stronger than nitrous oxide. Active. Anesthesia is easily manageable.

The excitement stage is short and weakly expressed. Wake up immediately. There are almost no consequences. Complications– cardiac arrhythmias. Explosive.

H2O - water, Liquid metal - mercury! The liquid state is usually considered intermediate between a solid and a gas: a gas retains neither volume nor shape, but a solid retains both.

The shape of liquid bodies can be determined entirely or partly by the fact that their surface behaves like an elastic membrane. So, water can collect in drops. But a liquid is capable of flowing even under its stationary surface, and this also means that its shape is not preserved ( internal parts liquid body).

Liquid molecules do not have a definite position, but at the same time they do not have complete freedom of movement. There is an attraction between them that is strong enough to keep them together. close range.

A substance in a liquid state exists in a certain temperature range, below which it turns into solid state(crystallization or transformation into a solid occurs amorphous state- glass), higher - into gaseous (evaporation occurs). The boundaries of this interval depend on pressure.

As a rule, a substance in the liquid state has only one modification. (The most important exceptions are quantum liquids and liquid crystals.) Therefore, in most cases, liquid is not only an aggregate state, but also a thermodynamic phase ( liquid phase) .

All liquids are usually divided into pure liquids and mixtures. Some liquid mixtures have great value for life: blood, sea ​​water etc. Liquids can act as solvents.
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Physical properties of liquids
Fluidity

The main property of liquids is fluidity. If you apply to a section of liquid that is in equilibrium external force, then a flow of liquid particles arises in the direction in which this force is applied: the liquid flows. Thus, under the influence of unbalanced external forces, the liquid does not retain its shape and relative arrangement of parts, and therefore takes the shape of the vessel in which it is located.

Unlike plastic solids, a liquid does not have a yield limit: it is enough to apply an arbitrarily small external force for the liquid to flow.
Volume conservation

One of characteristic properties liquid is what it has certain volume(at constant external conditions) . Liquids are extremely difficult to compress mechanically because, unlike gases, there is very little free space between the molecules. The pressure exerted on a liquid enclosed in a vessel is transmitted without change to each point in the volume of this liquid (Pascal’s law is also valid for gases). This feature, along with very low compressibility, is used in hydraulic machines.

Liquids generally increase in volume (expand) when heated and decrease in volume (contract) when cooled. However, there are exceptions, for example, water contracts when heated, at normal pressure and at temperatures from 0 °C to approximately 4 °C.
Viscosity

In addition, liquids (like gases) are characterized by viscosity. It is defined as the ability to resist the movement of one part relative to another - that is, as internal friction.

When adjacent layers of liquid move relative to each other, collisions of molecules inevitably occur in addition to that caused by thermal motion. Forces arise that inhibit orderly movement. At the same time kinetic energy ordered movement turns into thermal energy - the energy of chaotic movement of molecules.

The liquid in the vessel, set in motion and left to its own devices, will gradually stop, but its temperature will increase.

Lesson type: combined

Target

— formation of a holistic picture of the world and awareness of a person’s place in it based on the unity of rational-scientific knowledge and the child’s emotional and value understanding personal experience communication with people and nature;

Problem:

What is a body, substance, particle?

Tasks:

Distinguish between bodies, substances and particles,

Conduct experiments using laboratory equipment

Subject results

will learn

Characterize the concepts of “body”, “substance”, “particle”;

Distinguish between bodies and substances and classify them.

Universal learning activities(UUD)

Regulatory: adequately use speech to plan and regulate one’s activities; transform practical problem into cognitive.

Cognitive: pose and formulate problems, monitor and evaluate the process and result of activities (experience); transfer of information.

Communicative: cost monologue statement, argue your position.

Personal results

Motivation for learning activities

Basic concepts and definitions

Bodies, substances, particles. Natural and artificial bodies. Solid, liquid, gaseous substances

Checking readiness to learn new material

Remember into what groups all the objects that surround us can be divided.

Look at the diagram. What two groups can bodies be divided into? Give examples of bodies from each group.

Learning new material

Any item, any living creature can be called a body. A stone, a lump of sugar, a tree, a bird, a wire - these are bodies. It is impossible to list all the bodies; there are countless of them. The sun, planets, and the moon are also bodies. They are called celestial bodies

SUBSTANCES

Bodies are made up of substances. A piece of sugar is a body, and sugar itself is a substance. Aluminum wire is the body, aluminum is the substance.

There are bodies that are formed not by one, but by several or many substances. Very complex composition have living bodies. For example, plants contain water, sugar, starch and other substances. The bodies of animals and humans are formed by many different substances.

So, substances are what bodies are made of.

Distinguish solid, liquid And gaseous substances. Sugar and aluminum are examples of solids. Water is a liquid substance. Air consists of several gaseous substances (gases).

BodiesAndsubstances

Bodies. Substances

Experience. Fromwhatconsistsubstances

Threestatesubstances

PARTICLES

Experience. Let's take a body formed by one substance - a piece of sugar. Place it in a glass of water and stir. At first the sugar is clearly visible, but gradually becomes invisible. Let's taste the liquid. She's sweet. This means that the sugar did not disappear, it remained in the glass. Why don't we see him? Make a guess.

A piece of sugar has broken down into tiny pieces visible to the eye the particles of which it consisted (dissolved), and these particles mixed with particles of water.

Conclusion: experience proves that substances, and therefore bodies, consist of particles.

Every substance consists of special particles, which differ in size and shape from particles of other substances.

Scientists have found that there are gaps between particles. In solids these gaps are very small, in liquids they are larger, in gases they are even larger. In any substance, all particles are constantly moving.

Comprehension and understanding of acquired knowledge

Presentation "Bodies, substances, molecules"

BodiesAndsubstancesaroundus

1.Check with your textbook whether the statements below are true.

Any object, any living creature can be called a body.

Substances are what bodies are made of.

2. Select bodies from the list first, then substances. Test yourself on the Self-Test Pages.

Horseshoe, glass, iron, brick, sugar, watermelon, salt, starch, stone.

3.Using a model, show the process of dissolving a piece of sugar in water.

4. Using models, depict the arrangement of particles in solid, liquid, and gaseous substances.

Independent application of knowledge

What are bodies called? Give examples.

What are substances? Give examples. 3. What do substances consist of? How to prove this? 4. What can you tell us about particles?

Homework. Write in the dictionary: body, substance, particle.

Sources of information:

A. A. Pleshakov textbook, workbook The world around us, grade 3 Moscow

"Enlightenment" 2014

Presentation hosting the world around us

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 has been generally accepted that all known compounds are capable of existing in three states of aggregation: solid, liquid, and gaseous substances. However, careful research last decades in the field of astronomy, physics, chemistry, space biology and other sciences they proved 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 can be applied to the compounds in question is division based on the particles they contain. Not all gaseous substances are made of atoms. Examples of structures in which ions, molecules, photons, electrons, Brownian particles, and plasma are present also refer to compounds in this 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.

We can identify the most important physical properties 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 people. in human ways. 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 electric current 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, under certain conditions, are capable of turning into a liquid or solid phase, while 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. Besides 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, when reaching 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 main 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 weakly 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 gratings 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), and 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 lattice 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 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;
• sulfur dioxide;
• brown gas;
• freon;
• ethylene and others.

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

Methane and its homologues

Sometimes general concept"gas" refers to a natural mineral, which is a whole mixture of gaseous products mainly organic nature. It contains substances such as:

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

In industry they are very important, because it is the propane-butane mixture that is domestic gas, on which people cook food, 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, that's what they are direct participants 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 types of anaerobic bacteria can exist without it. 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 the atoms are particles of a gaseous substance, connected in pairs to each other due to covalent non-polar bond. However, not all halogens are gases. Bromine is a liquid under ordinary conditions, and iodine is an easily sublimable 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.