Notes on the Text

1. the radius is as much as 0.1X 10~^e m — радиус равен 0,1X IO“* i

2. a full stop - точка hath

3. in the course of — в ходе, в процессе

4. regular arrangement — упорядоченное расположение

^ ТЕХ Т. SOME FACTS ABOUT ATOMS

An atom may be spoken of as the smallest particle of ar substance. ,■ ,-w , /,

If atoms cannot be seen it does not necessarily mean thax they do not exist. It indicates that any particles, if present, must be extremely small. There are methods by means of which the sizes of atoms and their arrangement in molecules can be determined. One of these methods uses X-ray diffrac­tion.

The results of a number of investigations show that when atoms are in contact with other atoms in molecules, their ra­dius is as much as 0.1 XlO^-8 m (0.1 nm).

Some idea of how small atoms are can be obtained by imag­ining one million copper atoms (radius=0.13x 10~⁸ m (0.13 nm)). If these copper atoms are stacked one on top of the other, the pile will be as high as the full stop at the end of this sentence.

In the course of many investigations, chemists came to a conclusion that the atoms of different elements are all made essentially of three simple types of units, which were referred to as protons, neutrons, and electrons.

The following diagram shows us the constituents of the atom:

1. Atoms contain the following structural units:

Electrons t	Protons I	Neutrons 1
Charge —1,	Charge -f-1,	Zero charge,
very small relative	relative mass 1	relative mass 1
mass

2. The position and numbers of these structural units in an atom is shown below:

Electrons fill the space around the nucleus.

Number of electrons=Atomic number.

Very small nucleus.

Number of protons = Atomic number.

Number of protons + Number of neutrons = Relative atomic mass.

Number of electrons = Number of protons = Atomic number of element.

Number of protons + Number of neutrons = Relative atomic mass of element.

The numbers of electrons, protons, and neutrons in an atom of an element can be calculated if the atomic number and rela­tive atomic mass of the element are known:

It was also found that many elements and compounds are composed of small numbers of atoms which are held together irj a regular arrangement. These groups of atoms are refdrred to' as molecules. The gas hydrogen, for example, is composed of pairs of hydrogen atoms and each pair is called a rriofeciile and its formula is H₂. . -

Another example is the compound carbon dioxide which is composed of molecules, the formula is CO_a.

The Atomic Model

The electron, the proton, and the neutron gather together

into what can be called the atom. ^v’

Our concept of the atom derives from a series of observa­tions. As a result of these observations, we now believe that an atom is composed of a cloud of electrons that revolve about a central core of protons or of protons plus neutrons. Repeated ‘ experiments, which were referred to above, show that every • atom has the same number of electrons as well as protons. The positively charged protons form the rfucleus of the atom, and balance the positive charges of the protons in the core of the atom. The neutrons are also found in the nucleus of the atom.

'An atom has already been spoken of as the smallest unit of an element.

It is known that ninety-two elements occur in nature, and a number of others have been made by man in the laboratory. Every element is a special combination of protons, neutrons, and electrons. Each element is identified by the number of protons in its nucleus and is designated by a name and a symbol.

Element Number 1 is a combination of one proton and one electron. Long before its atomic structure was known, this element was referred to as hydrogen, or “water-former”, because water forms when hydrogen burns in air. Its symbol is H. Hydrogen has first place in the list of elements because it has one proton in its nucleus. Element 1 is followed by Ele­ment Number 2. It consists of two protons and two electrons. It was named helium, with the symbol He.

Remember the following words and		work combinations;
to mean	to stack H	to fill
to indicate	to obtain	nucleus
extremely	top	to calculate
size	essentially	to hold
to determine	to refer to as	evidence
diffraction	constituent	statement
to show	unit	to compose
radius	charge	to derive
as much as	relative	to charge to identify ■

Ex. 8. Answer the following questions:

1. What is an atom? 2. What does it mean if atoms cannot be seen? 3. What methods are used to determine the sizes of atoms? 4. What is the radius of an atom? 5. To what con­clusion did the chemists come? 6. What structural units do the atoms contain? 7. What space do the electrons fill? 8. How can the numbers of electrons, protons, and neutrons in an atom be calculated? 9, How many elements occur in nature?

10. Why is Element Number 1 referred to as “water-former”?

Ex. 9. Retell the text according to the following plan:

1. The definition of an atom.

2. The methods by means of which it is possible to deter­mine the size of an atom.

3. The size of an atom.

4. Three simple types of units.

5. The diagram showing the constituents of an atom.

6. The position and numbers of the structural units in an atom.

7. The numbers of electrons.

8. The number of elements occurring in nature.

Ex. 10. Read the following words, state parts of speech they belong to and translate them into Russian:

extremely, numerical, means, essentially, constituent, regular, relative, determination, unite, evidence, type.

Ex. 11. Translate the following sentences into Russian:

1. According to the atomic theory this means that the number of atoms of carbon in combination with the same num­ber of atoms of oxygen is two times as great in carbon monoxide as in carbon dioxide. 2. The velocity of a reaction means the amount of the material which undergoes change in unit time.

3. The heterogeneity of a substance may be shown by differ­ent means. 4. Fractional distillation is used extensively in chemical industry as a means of separating and purifying many products. 5. The average distance through which a molecule moves between collisions is called the mean free path. 6. The kinetic theory makes it possible to calculate the mean ve­locity of molecules.

Ex. 12. Open the brackets choosing the correct form of the adjective. Translate the sentences into Russian:

1. Atoms are not (smaller, the smallest) particles, but they are very small. 2. This discovery is (more important, the most important) than the previous one. 3. It is much (easier, the easiest) to make parts of plastics than of metal or wood. 4. This is (better, the best) laboratory in our Institute. 5. Alumin­ium is (lighter, the lightest) known metal. 6. Hydrogen is (lighter, the lightest) of the elements. 7. Beryllium is (less, the least) active member of the group, and there is a regular increase in activity from metal to metal in the order of in­creased atomic numbers. 8. Moscow University is (larger, the largest) University in our country. 9. (More, the most) char­acteristic chemical property of hydrogen peroxide is its great oxidizing power.

Ex. 13. Translate the following sentences into Russian, mind the Passive forms of the verbs:

1. Electrons have been spoken of as moving in orbits about the atomic nucleus. 2. This law is generally spoken of as the Second Law of Thermodynamics. 3. It had already been men-

tioned that many of the elementary gases could exist in diatomic molecules. 4. ' In general the oxidation number may be thought of as an electrical charge of the atom. 5. The results of our work will be discussed at the conference. 6. A base is referred to as a substance that accepts protons from another substance. 7. It has been noted that chlorine dioxide reacts with water. 8. The sodium salt is bemg₍ manufactured, in industrial quantities, ⁴'J 9. This method is being used in our laboratory. 10. The Insti­tute was being built when we came to this town.

Ex. 14. Choose the Russian equivalents from the right column:

like

because of closely to result in to pay attention nucleus

the same charge

nuclei

means

meaning

тщательно

приводить

обращать внимание

ядро

ядра

тот же заряд

средство

значение

подобный

из-за

Ex. 15. Translate the text paying attention to the translation of adjectives:

An atom is the smallest possible particle of any substance. Before, atoms were looked at as the smallest particles that can exist. But now it has been proved that atoms have a complicat­ed internal structure which is composed of particles which are much smaller still. When we say that an atom is the smallest particle of any substance, we mean that atom is the basic unit of a substance.

Ex. 16. Translate the sentences into Russian. Mind the use of “most”:

1. In the dye solution most dyes go into colloidal suspen­sion. 2. In most carbon compounds only one valence bond is held between adjacent carbon atoms. 3. The discovery of steel was one of the most important inventions of man, for it gave him one of the hardest materials. 4. In the atmosphere oxygen is for the most part uncombined. 5. Most of the interior of an atom can be considered as an empty space, similar to that between the planets. 6. Many ions, probably most of them, are hydrated in aqueous solution. 7. The most conve­nient method was that used by our scientists. 8. The most ex­tensive use of ammonium sulphate is in plant fertilizers. 9. Most of our students take an active part in the preparation for

this conference. 10. Unlike most salts the solubility of anhy­drous salt decreases with the rise in temperature.

Ex. 17. Read the text and retell it:

The Nuclei of Atoms

In 1911 the British physicist Ernest Rutherford carried out some experiments which showed that every atom contains, in addition to one or more electrons, another particle, called the nucleus of the atom.

Every nucleus has a positive electric charge. It is very small. It is about as big as an electron. It is very heavy.

There are many different kinds of nuclei. The nuclei of the atoms of one element are different from the nuclei of the atoms of every other element.

Grammar; 1. The Adverbs.

2. The use of very, the very. Text; The Nature of Ceramics.

LESSON 8

Ex. 1. Pronounce the following words:

non-metallic ['nonmi'taelik] matrix ['meitriks] primarily ['praimorih] covalent [kou'veibnt] i'- particularly [pa'tikjutali] vacancies ['veikansiz]

Hi и

OtM 1

ceramics [si'raemiks] natural ['naetfral] variety [va'raiatij strength [strerjO] comparatively [кэт'ргегэ

tivll] ' " О;'..' _t

durable ['djuarabl] OUc*^****' neighbour f'neiba] , surprising [sa'praizigjtftf^^^onize ['aianaizj pottery ['potarilf^fresistant [ri'zistant] lustrous ['hvstras] Дхиу. ^..silicon ['silikan] ruby ['ruibi] aluminium [.aelju'minjam]

iff

i /lc u. /

refractory [ri'fraektarijt:' '/'i^>giant [^aiant] lining ['lainig] OvauS"

Ex. 2. Read the following word combinations:

highly oxidized compounds ['haili *oksidaizd 'kompaundz] control devices [kan'troul di'vaisiz]

strongly resistant materials [^{strogli n'zistant mo4iaralz] highly ionized atoms ['haili 'aianaizd -aetamz] significant extent [sig'mfikant iks'tent] principal elements ['prinsapl 'elimantsj

nature ['neitfs] natural ['naetjYol)

attack [a'taek] definite f'defmit]

products ['prodakts] significant [sig'nifikant]

control [kan'troul]

Ex. 4. Form adverbs according to the model:

Model: warm + -ly = warmly

chemical, great, natural, essential, particular, strong.

Ex. 5. Translate the following sentences into Russian:

Note: hardly—едва nearly—почти

highly—весьма readily — охотно,

1 argely—главным образом, легко

преимущественно

1. The reaction of carbon with oxygen is highly exother­mic. 2. Up to now chemistry has largely been a matter of tak­ing natural products of the earth and converting them to man’s uses. 3. This element exists in two readily recognizable modifications: crystalline silicon and amorphous silicon. 4. Mercury oxide can be readily decomposed by heat. 5. There are many reactions which proceed readily, some even violently, if a trace of water is present. 6. For nearly two thousand years it was believed that all heavy objects fell faster than light ones. 7. One of the properties common to nearly all nuclear radiations are particles in their ability to ionize. 8. Hydrogen readily combines with fluorine and chlorine. 9. In many cases mixtures and compounds are not so readily distinguished. 10. There is hardly any living substance in nature which does not consist of compounds containing oxygen.

Ex. 6. Complete the following sentences using the verbs “to find” or “to find out” according to the model:

Model: 1. At last he found the article about the new methods of production of some synthetic products.

2. He carried a number of experiments as he wanted to find out the composition of this new substance.

1. After many years of hard work the scientist ... a new method of purifying water. 2. I should like . . . where this scientist will make his report about the refining of petroleum.

3. This material . . . wide application everywhere. 4. If you like .., about his new investigations in the field of me-

tallurgy, you had better speak to him. 5. Have you . . . what the term “chemical durability” means?

Ex. 7. Translate the following sentences into Russian:

Note: very (with adjectives and adverbs)—очень the very book — именно эта книга the very student — тот самый студент

1. This is the very material we need in our experiment. 2. At the very end the text was very difficult. 3. The very first step in applying the scientific method is to obtain some facts by observation and experiment. 4. He knows the subject very well as he works very hard. 5. In the very nature glass is brittle. 6. This is the very man who can help you.

Ex. 8. Translate the following sentences paying attention to the word “provided":

1. These investigations provided new methods of detecting very minute quantities. 2. Provided the temperature is kept constant the volume of a given amount of gas is inversely pro­portional to its pressure and directly proportional to its ab­solute temperature. 3. The steel may be provided with the desired degree of hardness. 4. The laboratory is provided with gas and running water. 5. The expedition was provided with food for many days. 6. Provided the relative pressure of water is higher in the atmosphere (surroundings), vapour will condensate.

Ex. 9. Translate the following word combinations:

main industrial products; mainly in industry; chemists are interested in this method; a very interesting new method; primarily ionic; is of prime importance; the very substance; a very good substance; by means of; the means of; nearly all the substances; near the limit.