Read paragraph 1, find the sentence with the Complex Object and translate it into Russian.

Read paragraph 3, find the sentences with the Complex Subject and translate them into Russian.

Read paragraph 4, find the sentence with the Emphatic construction and translate it into Russian.

Read the rest of the text and think of how many parts it can be divided into. What is each part about?

Translate the following into Russian.

1) В ходе этих открытий появились новые факты. 2) Мы попытаемся определить валентность углерода в этане. 3) Будет получен очень странный результат. 4) Великий русский химик выдвинул теорию, которая объяснила бы эти и многие другие факты. 5) Эти данные привели ученого к следующему выводу. 6) Только понимая внутреннее строение молекул, можно решить данную проблему. 7) Свойства вещества зависят также и от порядка, в котором его атомы соединяются.

Find suitable definition for each of the terms given.

a) Hydrocarbon; b) ethane; c) ethyl alcohol; d) acetic acid; e) propane; f) valence.

1. A colourless pungent (едкий) liquid, miscible (смешиваемый) with water, widely used in the manufacture of acetic anhydride (уксусный ангидрид), vinyl acetate, plastics, pharmaceuticals, dyes, etc. Formula: CH₃COOH. Systematic name: ethanoic acid (уксусная кислота).

2. Any organic compound containing only carbon and hydrogen, such as the alkanes, alkenes, alkynes, terpenes (терпены), and arenes.

3. The phenomenon of forming chemical bonds.

4. A colourless flammable liquid, the active principle of intoxicating drinks, produced by the fermentation of sugars, esp. glucose, and used as a solvent and in the manufacture of organic chemicals. Formula: C₂H₅OH.

5. A colourless flammable gaseous alkane found in petroleum and used as a fuel. Formula: CH₃CH₂CH₃.

6. A colourless odourless flammable gaseous alkane obtained from natural gas and petroleum: used as a fuel and in the manufacture of chemicals. Formula: C₂H₆.

Discuss the following.

1. What motivated the rapid advance of organic chemistry as science at the beginning of the 19^th century?

2. Can you give the baffling facts scientists faced in the middle of the 19^th century.

3. What is the reason for the diversity of organic compounds?

4. Why do you think it is carbon and not some other element that forms so many compounds?

5. What was the contradiction in the views of A.Butlerov and other scientists?

6. What are the main points of the theory of chemical structure?

TEXT 4. BUTLEROV’S THEORY OF THE CHEMICAL STRUCTURE OF ORGANIC COMPOUNDS. PART II

 

Let us consider the first of the Butlerov’s theoryprinciples as applied to hydrocarbons.

In what order are the atoms connected in a molecule of the simplest hydrocarbon, methane? We already know from inorganic chemistry that each hydrogen atom in it is connected with the carbon atom. It iseasy to see that this must be the case. If we were to assume, for instance, that any two of the hydrogen atoms were connected with each other, this would mean they had exhausted their valences and could not link up with other atoms. The four hydrogen atoms can combine to form a CH₄ molecule only through a quadrivalent carbon atom.

If we denote the valences of elements by a dash, we get the following picture of the bonds between theatoms in a methane molecule:

H

|

H— С —H

|

H

 

For all the carbon and hydrogen atoms inthe ethane molecule to be linked up in a single particle, the carbon atoms must evidently be connected:

| |

— C — C —

| |

 

The carbon atoms in such a molecule have used up one valence unit each (out of the four that each atom has) to form the bond between themselves. This means they each have three valence units that are free, by means of which they hold six hydrogen atoms:

H H

| |

— C — C —

| |

H H

 

In the molecules of propane C₃H₈ and butane C₄H₁₀ the atoms are evidently connected in the following way:

H H H H H H H

| | | | | | |

H — C — C — C — H H — C — C — C — C — H

| | | | | | |

H H H H H H H

The molecules of the other hydrocarbons with which we are familiar have a similar structure.

Now that you know the structure of these hydrocarbons, you will be able to provide answers yourself to some of the questions that baffled scientists at one time.

Is the valence of the elements violated in any of the compounds we have considered? No, carbon is quadrivalent in all of them. What accounts for the constant increment in the composition of hydrocarbon molecules? This is due to the fact that in the transition from one member of the series to the next the chain of atoms is each time extended by a CH₂ link. What is the reason for the diversity of organic compounds? It is apparently the special ability of the carbon atoms to link up with one another, forming chains.

With a knowledge of the structure of hydrocarbons, it is easy to understand the similarity of their chemical properties and, specifically, the reason why they do not add other substances through reactions of addition. In the molecules of these substances all the valence units of the carbon atoms have been used up: they have been saturated with hydrogen atoms to the highest limit. Accordingly, any further addition of atoms to the carbon is impossible; the only possibilities are the substitution of, say, chlorine atoms for the hydrogen atoms or the destruction of the molecule. That is why the hydrocarbons we have been considering are called saturated, or limit, hydrocarbons. Another name for them is paraffins (from the Latin parum affinis, which means "little affinity").

Substances similar in structure and chemical properties, but differing in the composition of their molecules by one or several CH₂ groups are called homologues and form homologous series. The hydrocarbons we have been considering – methane, ethane, propane, butane, etc. – are homologues; they form the homologous series of saturated hydrocarbons, or paraffins. The CH₂ group of atoms is called the homologous increment.

Chemical formulae showing the arrangement of the atoms in a molecule are called structural formulae.

Itshould be borne in mind that structural formulae only show the order in which the atoms are connected, but do not show the arrangement of the atoms in space. Therefore, no matter how we write the formula of propane, it will still be one and the same substance, since the order in which the atoms are connected has not changed.

H H H H H

| | | | |

H — C — C — C — H H — C —— C — H

| | | | |

H H H H H — C — H

|

H

The structural formulae of substances are often written in a shortened form, such as CH₃—CH₂—CH₃. Dashes in this case are used to show the bonds between carbon atoms, butnot the bonds between carbon and hydrogen atoms.

Tasks on the text

Memorize the following words and word combinations.

1. to assume[q`sjHm] – 1)принимать; 2) допускать, предполагать 2. for instance – например 3. to exhaust[Ig`zLst] – израсходовать, истощать 4. to denote [dI`nqVt] – отмечать, показывать, значить, обозначать 5. particle[`pRtIkl]– частица; крупица 6. to use up – израсходовать, использовать 7. to violate [`vaIqleIt] – нарушать 8. to account for – объяснять, отвечать 9. increment [`INkrImqnt] – возрастание, прирост 10. transition [trxn`zIS(q)n] – перемещение, переход

11. extend [Ik`stend] – 1) простираться, тянуться; 2) расширять; удлинять 12. specifically – в частности, особенно, в особенности, а именно, конкретно 13. saturated[`sxC(q)reItId] – насыщенный 14. substitution [,sAbstI`tjHS(q)n] – замена, замещение 15. chlorine [`klLrJn] – хлор 16. destruction [dI`strAkSqn] – разрушение 17. affinity [q`fInqtI] – сродство 18. homologue [`hPmq,lPg] – гомолог 19. homologous [hqV`mPlqgqs] – гомологический 20. butane [`bjHteIn] – бутан

Find the equivalents for the words and word combinations in the left column from the column in the right.

1) давайте рассмотрим; 2) четырехвалентный; 3) например; 4) с помощью; 5) следующим образом; 6) очевидно, несомненно, явно; 7) объяснять; 8) благодаря; 9) образуя цепи; 10) соответственно; 11) сокращенная форма; 12) одно и тоже; 13) гомологичный ряд; 14) переход от одного к другому; 15) иметь в виду, помнить; 16) расположение в пространстве; 17) структурные формулы; 18) вследствие этого; поэтому, следовательно.

a) account for; b) evidently, apparently; c) quadrivalent; d) by means of; e) due to; f) in the following way; g) for instance; h) forming chains; i) let us consider; j) transition from one to the next; k) one and the same; l) shortened form; m) arrangement in space; n) structural formulae; o) accordingly; p) bear in mind; q) homologous series; r) therefore.

Find the pairs of synonyms.

Particle, connect, feature, apparently, quadrivalent, account for, explain, evidently, link up, mean/define, exhaust, use up, property, hence, denote, tetravalent, fraction, therefore.