Anglysky_-_metodichka

properties, its melting point being of 3.135 °F. Each liquid has to take the shape of the vessel it occupies.

Physical States of Substance

There are three physical states of substance, namely, the gaseous, liquid and solid

states.

GASES are characterized by their ability to fill uniformly any volume placed at their disposal. This property of gases is due to the extraordinary mobility of their particles. That the particles of gases are at great distance from one another has been confirmed by the high compressibility of gases. Under such conditions the mutual attraction between particles is very small and doesn't keep them from flying in all directions. The particles move so swiftly and unorderly that any regular arrangement is out of the question.

LIQUIDS differ from gases in that they occupy a definite volume at any given temperature. The very slight compressibility of all liquids shows that their particles are much more crowded than those of gases. Therefore the mutual attraction between the particles is much more pronounced and keeps them from flying apart. This has to be explained by the consistency of the volume of liquids. Liquids spread under the influence of gravity and thus have not their own shape, always taking the shape of the vessel they occupy. Only when in very small quantities (drops) are liquids capable of retaining their own shape.

SOLIDS, contrary to liquids and gases, have definite independent shape and retain it regardless of their position. The particles of a solid are so rigidly connected to one another that they cannot move from place to place. True, even in solids the particles retain some motion, but in this case it has the character of minute vibrations about definite points.

From this brief review of the properties of substance in its various states it follows that the particles forming a substance have a regular arrangement only in the solid state.

E X E R C I S E S

I.Define the functions of the verb "to have" in the following sentences and translate them into Russian:

1.The solution has to be transferred into another test tube. 2. Today chemists have not only synthesized many of organic substances occurring in nature but have prepared substances that do not occur in nature such as plastics, different types of rubber, medicines, etc. 3. Gases, contrary to liquids and solids, have no definite or independent shape regardless of their position. 4. The term "X-ray" is familiar to the civilized world and there are few of us who have not been subjected to these radiations by the doctor when he wants to know more about broken bones or organic disorders within our bodies.

5.Everyone knows that steel is melted in blast furnaces, but only the experts know that in order to utilize the blast furnace in the best way possible, the level of the furnace charge has to be on a definite mark all the time. 6. This substance is gaseous and has no odour.

II.Translate the following groups of words:

1.to occupy, occupation 2. gas, gaseous 3. to compress, compression, compressibility 4. to soften, soft, softness, softly 5. constant, constancy, constantly 6. to arrange, arrangement 7. mobile, mobility 8. to regard, regardless 9. to fill, full 10. strict, strictly 11. to melt, melting, melting point 12. distance, distant.

III.Form nouns from the following verbs and translate them into Russian:

to flow, to break, to verify, to retain, to spread, to fly, to occupy, to establish, to soften, to arrange, to be able, to review, to neutralize, to conform, to shape, to transit, to melt, to crowd.

IV. Form adjectives from the following nouns:

gas, ability, mobility, distance, constancy, shape, rigidity, acidity, alkalinity, regard, swiftness.

V.Form adverbs from the following adjectives:

soft, distant, constant, swift, rigid, strict, essential, converse, mutual, dependent, definite.

VI. Arrange the following words in pairs of synonyms:

keep, destroy, establish, shape, pronounced, swiftly, minute, break, state, shapeless, form, rapidly, little, namely, that is, retain, marked, amorphous.

VII. Give antonyms to the following words:

constancy, break, soften, swiftly, orderly, minute, mobile.

VIII. Translate the following sentences into English:

1. Существуют три физических состояния вещества – газообразное, жидкое и твёрдое. 2. Частицы газа находятся на большом расстоянии друг от друга. 3.

Жидкости перемещаются под влиянием тяжести и, таким образом, не имеют своей специфической формы. 4. Твёрдые вещества в противоположность жидкостям и газам имеют определённую форму.

IX. Answer the following questions:

1. What three physical states of substance do you know? 2. What are gases characterized with? 3. What does the high compressibility of gases confirm? 4. What is the difference between gases and liquids? 5. Do liquids have their own shape? 6. How are the particles of a solid connected?

X.Translate with a dictionary:

CRYSTALLINE AND AMORPHOUS SUBSTANCES

Most solids have crystalline structure. This can easily be verified while breaking a piece of substance and examining its fracture. Usually (for example, in sugar, sulphur, metals) tiny crystalline faces at various angles to each other can easily be detected on the fracture, sparkling due to various reflection of light. If the crystals are very small, the crystalline structure of the substance has to be established by means of a microscope. There are solid substances whose fracture gives no indications of crystals. For example, if we break a piece of ordinary glass, its fracture will be found smooth and bounded, unlike the fractures of crystalline substances, by curved instead of plane surfaces. A similar picture is observed after pieces of pitch, glue and certain other substances have been broken. All such substances are called amorphous (i.e., formless).

XI. Translate into Russian without a dictionary:

The difference between crystalline and amorphous substances is essentially pronounced after they have been heated.

While each crystalline substance melts at a strictly definite temperature and passes back from the liquid to the solid state at the same temperature, amorphous substances have no constant melting point. When an amorphous substance has to be heated it gradually softens, then begins to flow and finally becomes quite liquid. While cooling it hardens. It is impossible to establish the moment of transition of an amorphous substance from one state into another.