Some Physical Properties of Air

The physical properties of air were studied long before its chemical properties. Aristotle¹ (384 B. C.²) in spite of his confused ideas³ on the nature of gases considered that air was a material substance which possessed weight; another Greek scientist (117 B. C.) described some experiments which were made in order to prove that air is a material substance. For instance he said: «If we invert⁴ the open end of a vessel, having only one opening, in water, the water will not enter; if a hole be made in the upper part of the vessel, water comes in and air comes out. If we placed our hand over the opening we should feel a stream of wind which is moving air.»

In 1774 the French scientist Lavoisier made a large number of experiments in order to prove the hypothesis that when metals are heated in air, the increase in weight is due to fixation⁵ of the air by the metal.

However it was the gifted⁶ Russian scientist M.V. Lomonosov who had come to the same conclusion⁷ in 1756, i.e. eighteen years before Lavoisier.

Примечания к тексту

1. Aristotle [ˈQrIsttl] – Аристотель (384–322)

2. B. C. (before Christ) – до нашей эры

3. confused ideas – сбивчивые представления

4. invert [InˈvÎ:t] – переворачивать

5. fixation [fIkˈseIS(«)n] – зд. поглощение

6. gifted [ˈgIftId] – талантливый

7. to come to the conclusion – прийти к заключению

 

XI. Расскажите о свойствах воздуха, пользуясь текстами 7 А и 7 В.

 

LESSON 8

Грамматика. Формы инфинитива.Субъектный инфинитивный оборот (сочетание глагола-сказуемого в страдательном залоге с инфинитивом).

Предтекстовые упражнения

I. Переведите следующие предложения на русский язык:

 

1. The composition of air is found to vary slightly with elevation. 2. The air is known to contain one fifth oxygen by volume. 3. Most substances have been found to expand as the temperature rises. 4. The temperature lower than -273° is not known to exist. 5. Water can be said to be a universal solvent. 6. Ground water has been stated to contain a great deal of impurities. 7. Water was believed by the ancients to be an element. 8. Oxygen can be said to represent the most widely distributed element on the Earth. 9. Hydrogen peroxide has been shown to resemble ozone in many ways. 10. Hydrogen peroxide is found to act both as a vigorous oxidizing agent and as a reducing agent. 11. Phosphorus and nitrogen have been proved by many experiments to differ radically in many respects. 12. Silicon is said to play an important part in the inorganic world. 13. The importance of carbon in organic chemistry is considered to result from its possessing the ability to form carbon-carbon bonds.

II. Прочитайте и переведите следующие предложения, обращая внимание на выделенные слова:

as compared (to, with) – по сравнению

The electrons and the nucleus are very small as compared with the size of the atom.

 

except (for) – за исключением

The chemical properties of ozone are similar to those of oxygen except for its greater chemical activity.

 

III. Прочитайте и переведите следующие слова без словаря:

 

portion [ˈpɔːʃ(ə)n], proton ['prəUtn], neutron [ˈnjuːtrn], electricity [ɪlekˈtrɪsɪtɪ], neutral [ˈnjuːtrəl], equal [ˈiːkwəl], mass [mæs], opposite ['pəzɪt], plus [plʌs], minus ['maɪnəs], diameter [daɪ'æmɪtə], centimeter (cm) [ˌsentɪ'miːtə]

 

IV. Запомните чтение следующих слов:

 

indivisible [ˌɪndɪ'vɪzəbl], impenetrable [ɪm'penɪtrəbl], negligible ['neglɪʤəbl], sign [saɪn], whole [həUl]

 

TEXT 8 A

Structure of Atoms

All kinds of matter are now known to consist of little particles called molecules; these molecules in turn are discovered to consist of still smaller particles called atoms. The name “atom” comes from the Greek word meaning “indivisible” because atoms were supposed to be completely indivisible. Until the end of the nineteenth century an atom was considered to be a “simple, solid, hard, impenetrable particle”. Now it is believed to contain (except for hydrogen) three kinds of particles, these occupying only a portion of the whole space of the atom. The particles are electrons, protons, and neutrons. The existence of these particles in the atoms of the elements is fully established.

Electrons are negatively charged. They are thought to lie in different groups about the nucleus of the atom.

If atoms of matter contain negative electricity it is evident that they must contain also positive electricity in an equal amount; otherwise they would not be electrically neutral.

The positively charged atom of hydrogen is a proton. The hydrogen atom is stated to contain only one electron and one proton, and when the electron is removed from the atom, only the proton remains. Since the electron’s weight is considered to be almost negligible, the mass of the proton is very nearly equal¹ to the mass of the hydrogen atom. The mass of the proton is found to be 1836 times greater than that of the electron. The electrical charge of the proton is equal in magnitude to the charge of the electron, but it has the opposite sign (+ instead of ˗ ²).

The neutron has no charge at all and its mass is assumed to be approximately equal to that of the proton.

The electrons are the outer portion of the atom. The electrons and the nucleus are very small as compared with the size of the atom, which, therefore, appears to be composed largely of empty space. The diameter of the whole atom is estimated to be of the order of 10^-8 cm, while that of the nucleus is believed to be very much smaller.

The atomic weight of an element tells us the number of protons and neutrons in the nucleus of an atom. Now if we could determine the positive charge of the nucleus, we should then know the number of electrons in the atom, as the total charge of electrons is equal to the charge of the nucleus.

 

Примечания к тексту

1. very nearly equal – почти равна

2. – (minus) – минус

Запомните следующие слова:

approximately, as compared with, charge, consider, empty, estimate, fully, in turn, kind, largely, mean, negative, occupy, otherwise, particle, positive, sign, size

Упражнения

I. Переведите следующие предложения на русский язык:

1. Nitric acid has been found to react with many metals. 2. Hydrogen gas is said to diffuse through solid platinum, iron, etc. 3. Solutions are considered to be homogeneous mixtures which cannot be separated into their constituent parts by mechanical means. 4. Many reactions are known to be accompanied by an absorption of heat. 5. The amount of heat evolved during the formation of a given compound is proved to be the same whether the compound is formed directly or in a series of intermediate stages. 6. A very considerable number of aqueous solutions of acids, bases, and salts are reported to furnish a much greater osmotic pressure than one would expect. 7. The molecules of sodium chloride were supposed to be dissociated in aqueous solutions into two parts – Na and Cl. 8. Chemistry can be said to be largely an experimental science. 9. Thorium is not known to occur with any valence except 4.

 

II. Дайте анализ следующего предложения и переведите его на русский язык:

 

To obtain crystals of arsenic, grey arsenic is to be quickly heated in a current of hydrogen, black glittering crystals of arsenic being deposited near the hot portion of the tube followed by the formation of a yellow powder.

 

III. Дайте недостающие основные формы следующих глаголов:

 

to know, to come, to think, to tell, to find

 

IV. Дайте антонимы к следующим словам:

 

big, the beginning, soft, positive, complex, the same, unequal, to stay

 

V. Найдите в тексте эквиваленты к следующим словосочетаниям:

 

в свою очередь, еще меньшие частицы, за исключением водорода, в равном количестве, в … раз больше

 

VI. Переведите следующие предложения на русский язык, обращая внимание на выделенные слова:

 

1. Oxygen is twice as soluble as compared to nitrogen. 2. Hydrofluoric acid is a relatively weak acid as compared with the binary acids of the other elements. 3. Sodium is very unlike the common metals except that it also has a metallic luster. 4. Corundum is the hardest of all naturally occurring substances except diamond.

 

VII. Дайте краткие утвердительные и отрицательные ответы на следующие вопросы:

 

1. Do all kinds of matter consist of molecules? 2. Are atoms indivisible? 3. Must atoms contain positive electricity? 4. Has the electrical charge of the proton the opposite sign as compared with that of the electron charge? 5. Has the neutron got any charge?

 

VIII. Ответьте на следующие вопросы:

 

1. What do all kinds of matter consist of? 2. What is the meaning of the Greek word “atom”? 3. How many kinds of particles does an atom contain and what are their names? 4. What is a proton? 5. How many electrons and protons does the hydrogen atom contain? 6. What sign has the electrical charge of the proton?

 

IX. Прочитайте текст 8 В, не пользуясь словарем:

TEXT 8 B