I. Find out the words in the dictionary. Write them down and learn

X. Fill in the prepositions, if necessary.

1. Physics is concerned ___ studying the properties of matter, forc-

es and energy.

2. Molecules consist ___ groups ___ atoms

3. But ___ gases, the molecular force can be neglected.

19

4. Just as substances can be broken ___ ___ molecules, molecules

can be broken ___ ___ atoms.

5. There are three types ___ particles that can be considered as

making ___ a typical atom.

6. The neutron is a particle ___ no electrical charge.

XI. Define whether the sentences are true or false.

1. Physics is concerned with numbers, chemical reactions and dif-

ferent functions.

2. All molecules in an atom exert a force on each other.

3. Molecules consist of nothing. They are not dividable particles.

4. In solids and liquids, the molecules move relatively slowly.

5. An atom is the biggest particle that can represent a particular

chemical element.

6. There are 6 types of particles that can be considered as making

up a typical atom.

7. The neutron is a positively charged particle.

8. Proton is a particle with no electrical charge.

XII. Practice with someone asking and answering.

1. What is physics concerned with?

2. In what way do physicists regard substances?

3. What idea does experimental evidence support?

4. Are the molecules identical only in mass for any given single

substance?

5. Do all molecules in a substance exert a force on each other?

6. What do molecules consist of?

7. How do the molecules move in solids and liquids?

8. Why can the molecular force often be neglected in the study of gases?

9. What provides evidence of the existence of molecules?

10. Into what constituents can molecules be broken down?

11. What is the smallest particle that can represent a particular chem-

ical element?

12. How many types of particles are there, particles that can be

considered as making up a typical atom?

XIII. Put questions to the following sentences.

1. All molecules in a substance exert a force on each other. (General)

2. In solids and liquids, the molecules move relatively slowly. (Special)

3. There are three types of particles. (Disjunctive)

4. The neutron is a particle with no electrical charge. (Special)

5. The proton has a single positive charge. (Alternative)

6. Electrons play a major role in determining the properties of the

various elements. (General)

7. In the study of gases the molecular force is neglected. (Special)

XIV. Dictate the following sentences in English to your fellow-students. Check them together.

1. Physics is concerned with studying the properties of matter, forc-

es, and energy.

2. Physicists regard substances in terms of their basic constituents.

3. Matter is composed of tiny particles, called molecules.

4. Atoms consist of electrons and nuclei.

5. The existence of molecules is provided by various phenomena,

such as Brownian motion.

6. There are three types of particles: electrons, neutrons and protons.

7. The neutron is a particle with no electrical charge.

UNIT 4

I. Find out the words in the dictionary. Write them down and learn.

to possess, cohesion, attractive forces, rigid, repulsive forces,

to retain, crystalline, amorphous, to melt, lattice, a melting point,

however, negligible, to repel, to approach, because of, to cause, to

vibrate

II. Read the text. Use a dictionary, if necessary.

TEXT: «STATES OF MATTER»

All substances can, under the right conditions, exist as a solid, liquid, or gas. These are the three basic physical states (or phases) of matter. Solids possess the property called cohesion; that is, their component particles (atoms or molecules) are held together by attractive forces. As a result, solid substances are rigid and retain their shape unless deformed by external forces. There are two principal types of solids: crystalline and amorphous. Crystalline solids have definite crystalline structures. Most also melt at specific temperatures to become liquids. Examples include metals, ice, and many plastics, in addition to obviously crystalline substances such as common salt and diamond. In contrast to crystalline solids, amorphous solids have neither crystalline structures nor specific melting points. Glass is an example of amorphous solids. Liquids represent the intermediate stage between solid and gas. A liquid’s atoms or molecules have some degree of cohesion and so tend to remain together. But they are not rigidly linked and can therefore move in relation to each other – which is not possible in solids. For this reason liquids flow and in a gravitational field take on the shape of the vessels in which they are contained. In a gas the constituent particles have negligible cohesion and can therefore move almost completely independently of each other. Like liquids, gasses flow and assume the shape of their containers. Unlike liquids, however, gasses always fill the entire space in their containers and the container needs to be closed if the gas is not to escape. The attractive forces between atoms or olecules in a solid are balanced by repulsive forces. As two of these particles approach each other, the outer electrons of one repel the outer electrons of the other, and the atoms or molecules move apart. But because of the attractive forces between them, they move back toward each other again. The overall result of the attractive and repulsive forces is to cause each of the atoms or molecules in a solid to vibrate continually about the same position in a lattice. The atoms or molecules of a liquid are also affected by attractive and repulsive forces. But a liquid is hotter than the same substance in solid form and its vibrating particles therefore have greater kinetic ener gy – that is, they vibrate more violently. As a result, the attractive forces cannot hold them in a lattice, and they are relatively free to move. In a gas the atoms or molecules have so much energy that they have largely broken free of the influences of the attractive and repulsive forces and, therefore, have almost complete freedom of movement.

III. Translate the words of the same root. Define parts of speech.

to exist – existence – existent

obvious – obviously – obviousness

molecule – molecular – intermolecular

to attract – attraction – attractive

violent – violently

to move – movement

atom – atomic – interatomic

to shape – shape – shapeless – shapelessness

relativity – relative – relatively

to add – addition

definite – definitely – indefinitely

to form – formation – deformation

complete – completely – completeness

to assume – assumption

to depend – dependence – dependent – independent – independently

to contain – container

entire – entirely

to specify – specific – specifically – unspecified

possible – impossible

IV. Practice the following speech patterns.

Pattern 1. Atoms move in relation to each other.

1. Molecules

2. Particles

3. People

4. Planets

5. Neutrons

6. Protons

7. Electrons

Pattern 2. Solids possess the property called cohesion.

1. liquids – fluidity 4. solids – hardness

2. gases – volatility 5. solids – strength

3. plasma – fluidity 6. solids – elasticity

V. Find the sentences that can’t be found in the text.

1. A solid substance such as ice may be changed into a liquid state

to become water.

2. Solids possess the property called cohesion.

3. Liquids represent the intermediate stage between solid and gas.

4. Solids have a definite volume and shape, liquids have a definite

volume but no shape.

5. The attractive forces between atoms or molecules in a solid are

balanced by repulsive forces.

6. A liquid is hotter than the same substance in solid form and its

vibrating particles have greater kinetic energy.

VII. Translate the following word combinations and noun groups into Uzbek.

1. under the right conditions _______________________________

2. deformed by external forces _____________________________

3. are held together by attractive forces _______________________

4. as a result ___________________________________________

5. to melt at specific temperatures ___________________________

6. the intermediate stage between solid and gas ________________

7. degree of cohesion ____________________________________

8. tend to remain together _________________________________

9. therefore ____________________________________________

10. however ___________________________________________

11. the shape of the vessel _________________________________

12. complete freedom of movement _________________________

VIII. Fill in the missing words.

1. All substances can ___ as a solid, liquid or gas.

2. Solids possess the ___ called cohesion.

3. In solids the component particles are held together by ___ forces.

4. Crystalline solids have ___ ___ structures.

5. Most solids ___ at specific temperatures to become liquids.

6. Amorphous solids have neither crystalline structures nor ___ ___ points.

7. In a gas the constituent particles have ___ cohesion.

8. Like liquids, gasses flow and ___ the shape of their containers.

IX. Fill in the prepositions if necessary.

1. In a gas the particles can move almost completely independently ___ each other.

2. The attractive forces between atoms or molecules ___ a solid are balanced ___ repulsive forces.

3. As two of the particles approach ___ each other, the outer electrons of one repel the outer electrons of the other, and the atoms or molecules move ___.

4. Because of the attractive force between them, they move ___ ___ each other again.

5. In a gas the atoms or molecules have so much energy that they have largely broken free ___ the influences ___ the attractive and repulsive forces.

X. Practice with someone asking and answering.

1. In what forms can all single substances exist?

2. What main property do solids possess?

3. What do we mean by cohesion?

4. What are two principal types of solids?

5. Crystalline solids have definite crystalline structures, don’t they?

6. Do they melt at specific temperatures?

7. What are the examples of crystalline solids?

8. Do amorphous solids have crystalline structures and specific melting points?

9. What are the examples of amorphous structures?

10. Liquids represent the intermediate stage between solid and gas, don’t they?

11. What are the properties of liquids?

12. Why do liquids flow?

13. Do the constituent particles in a gas have any cohesion?

14. Do gases behave like liquids? Are gases similar to liquids?

15. Are the attractive forces between atoms or molecules in a solid balanced by other forces?

16. What is the overall result of the attractive and repulsive forces in a solid?

17. Are the atoms or molecules of a liquid also affected by attractive and repulsive forces?

18. Why are the atoms or molecules in a gas free of the influences of the attractive and repulsive forces?

XI. Put questions to the following sentences.

1. Crystalline solids have definite crystalline structures. (General)

2. Glass and many resins are examples of amorphous solids. (Alternative)

3. The attractive forces cannot hold particles in a lattice. (Disjunctive)

XII. Dictate the following sentences in English to your fellow-students. Check them together.

1. All single substances can exist as a solid, liquid, or gas.

2. Crystalline solids have definite crystalline structures.

3. Most solids melt at specific temperatures to become liquids.

4. A liquid’s atoms or molecules have some degree of cohesion and so tend to remain together.

5. Liquids flow and in a gravitational field take on the shape of the vessels in which they are contained.

6. The overall result of the attractive and repulsive forces is to cause each of the atoms or molecules to vibrate continually about the same position in a lattice.

7. A liquid is hotter than the same substance in a solid form and its vibrating particles have greater kinetic energy.

UNIT 5

I. Find out the words in the dictionary. Write them down and learn.

strength, elasticity, stiff, to stretch, to compress, strain, tensile,

shear, compressive, to twist out, to pull apart, repulsive, bond, hard-

ness, pressure, density, to expand, cohesion, tension, to cancel out

II. Read the text. Use a dictionary, if necessary.

TEXT: «PROPERTIES OF SOLIDS AND LIQUIDS»

The forces that hold atoms and molecules in place give solids their strength. The strength of a material is determined by measuring its elasticity – that is how stiff it is and how it behaves when it is stretched or compressed. Elasticity is measured as the ratio of stress to strain. Stress is defined as the force acting on a material divided by the area over which the force is applied. Stress may be applied in three different ways: tensile, shear and compressive. Tensile stress causes a material to become elongated (stretched), and shear stress causes it to be twisted out of shape. In both cases the component atoms or molecules are pulled apart as they move from their original positions. When the stress is removed, the attractive forces between the atoms or molecules pull them back together again, and the material is restored to its original shape. Compressive stress forces the atoms or molecules together, and it is the repulsive forces that restore the shape of the material when the stress is removed. If stress is applied to a material and slowly increased, the material accordingly changes shape. But at a certain point it reaches its elastic limit. Another property of solid materials that depends on the strength of the bonds between atoms or molecules is hardness. As in a solid, the atoms or molecules of a liquid are held together by attractive forces. But these forces are not great enough to hold the atoms or molecules in a fixed pattern, they move about on random. As a result, a liquid can flow and it cannot be stretched or istored. Like a solid, it can be compressed slightly and shows the same sort of elasticity when subjected to compressive stress. Unlike a solid, but like a gas, a liquid exerts pressure, which at any point depends on the depth and the density of the liquid. A liquid does not expand to fill the whole of the volume available to it. Instead, the cohesion between its molecules forces it to maintain a fixed volume (at a given temperature). It takes on the shape of all or part of its container – but this is only because the forces of gravity makes it do so. In zero gravity conditions a liquid takes on the shape with the minimum possible surface area – that is, a sphere. The fact that a liquid tends to take on a spherical shape is due to a phenomenon known as surface tension. Inside a volume of liquid all the atoms or molecules attract each other equally. Each molecule experiences attractive forces in all directions and they cancel out ach other. But the atoms or molecules on the surface experience few, if any, attractive forces from the outside. As a result, the forces between them and inner molecules tend to pull them inwards and towards each other.

III. Define by suffix speech parts of the following words and trans-

late them:

Generally, collection, elasticity, define, different, compressive,

position, attractive, repulsive, restore, slowly, remove, accordingly, hard-

ness, move, density, available, container, spherical, phenomenon, equally,

direction, inner.

V. Find Uzbek equivalents to the following words and expressions:

1. to hold atoms and molecules _____________________________

2. the strength of a material _______________________________

3. stiff _______________________________________________

4. may be applied ______________________________________

5. to become elongated ___________________________________

6. molecules are pulled apart ______________________________

7. attractive force _______________________________________

8. to pull back __________________________________________

9. repulsive forces _______________________________________

10. to restore __________________________________________

11. a fixed pattern _______________________________________

12. the density of the liquid ________________________________

13. surface tension ______________________________________

14. to pull inwards and towards _____________________________

VI. Fill in the gaps with the following words.

tension, to strain, tensile, liquid, compressive, bonds, strength,

hardness, ratio, shear, repulsive, to stretch, exerts, solid

1. The forces that hold atoms and molecules in place give solids their ____.

2. Elasticity is measured as the ____ of stress to ____.

3. Stress may be applied in three different ways ____, _____, _____.

4. ____ stress causes a material to become elongated.

5. ____ stress forces the atoms or molecules together, and it is the ____ forces that restore the shape of the material.

6. Another property of ____ materials that depends on the strength of the ____ between atoms and molecules is ____.

7. A ____ can flow.

8. A liquid ____ pressure.

9. The fact that a liquid tends to take on a spherical shape is due to a phenomenon known as surface ____.

VII. Fill in the prepositions, if necessary.

1. The strength ____ a material is determined ____ measuring its elasticity.

2. Shear stress causes it to be twisted _____ shape.

3. In both cases the component atoms or molecules are pulled ___ as they move from their original positions.

4. The material accordingly changes _____ shape.

5. Another property of solid materials that depends _____ the strength of the bonds _____ atoms and molecules is hardness.

6. Each molecule experiences attractive forces _____ all directions.

7. ____ a volume of liquid all the atoms or molecules attract each other equally.

VIII. Define whether the statements are true or false.

1. The forces that hold atoms and molecules in place don’t give

solids their strength.

2. The strength of a material is determined by measuring its elasticity.

3. Stress is defined as the force acting in a material.

4. Stress may be applied in four different ways.

5. Another property of solid materials that depends on the strength of the bonds between atoms and molecules is softness.

6. Atoms or molecules of a liquid are held together by attractive forces.

7. These forces in liquids are great enough to hold atoms or molecules in a fixed pattern.

8. A liquid always expands to fill the whole of volume available to it.

9. The fact that a liquid tends to take on a spherical shape is due to surface tension.

IX. Put questions to the following statements.

1. The forces that hold atoms and molecules in place give solids their strength.

2. The strength of a material is determined by measuring its elasticity.

3. Elasticity is measured as the ratio of stress to strain.

4. The atoms or molecules of a liquid are held together by attractive forces.

5. A liquid can flow.

6. A falling drop of water tends to take the shape of a sphere.

7. Another property of liquids is adhesion.

UNIT 6

I. Find out the words in the dictionary. Write them down and learn.

to comply, pure, outside, a mixture, exceptional, solution, to

diffuse, parchment, crystalloid, colloid, to arrange, to fix, a ther-

mometer, a plane, polarized light, to create, thermonuclear, to alter,

voltage, a conductor, fusion, a source of power

II. Read the text. Use a dictionary, if necessary.

TEXT: «UNUSUAL STATES OF MATTER»

Some substances exist in states that do not comply with the normal definitions of a gas, a liquid, or a solid. For example, jelly is neither a true solid nor a liquid, and smoke is neither a pure gas nor a solid. Matter in stars and in the tails of comets exists as a plasma, a mixture of charged particles that is outside the normal definition of a gas. In general, a plasma can exist only at extremely high temperatures. At extremely low temperatures, approaching absolute zero, some materials take on remarkable properties. Although they are not strictly different states of matter, their behaviour is exceptional. Colloids. In 1861, the physical chemist Thomas Graham discovered that some substances in solution, such as salt, sugar, and copper sulfate, diffuse through parchment, whereas others, such as glue and gelatine do not. He therefore divided substances into two groups: crystalloids (that diffuse through parchment) and colloids (that do not diffuse). And he believed that the difference between a crystalloid and a colloid depended largely upon particle size. We now know that Graham was broadly correct. But we also know that most crystalloids can be brought into the colloidal state. A colloid is a solution in which the component particles are large molecules or clumps of small molecules. Liquid crystals. The liquid state is intermediate between the solid state and the gaseous state. Some substances, however, are intermediate between solids and liquids. In a liquid crystal the atoms or molecules are arranged in a pattern, like those of a solid crystal. But the pattern is not completely fixed; it can be altered by heat or an electric field. Some liquid crystals change colour at certain temperatures and can, therefore, be used in liquid crystal thermometers. In others an electrical voltage causes a change in patterns that alters the plane of polarized light. Such types are used to make liquid crystal displays for watches and calculators. Plasmas. A plasma is sometimes described as being the fourth state of matter – that is, one phase farther on from a gas. In fact a plasma is created by heating a gas to such a high temperature that its atoms or molecules lose electrons and become ions. The gas is almost fully ionized and becomes a very good electrical conductor. The gases that are involved in the thermonuclear reactions of the sun and other stars are in the form of a plasma. Scientists are trying to recreate such a plasma on earth by eating the gases deuterium and tritium (isotopes of hydrogen) to tens of millions of degrees in special installations. In this way, they hope to produce a controlled thermonuclear fusion reaction as a source of power.

III. Find nouns (a), adjectives (b) and adverbs (c) in the following words. Translate all of them:

substance, definition, pure, mixture, normal, extremely, remarka-

ble, strictly, behaviour, exceptional, largely, crystalloid, broadly, colloi-

dal, solution, intermediate, gaseous, completely, electric, calculator, fully,

conductor, thermonuclear, installation, power, certain, property