Lesson 12

  1. Lesson 10
  2. Lesson 11
  3. Lesson 13
  4. Lesson 14
  5. Lesson 15
  6. Lesson 16

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Section I

Ex. 1. Pronounce the following words:

', 3- , , .

a) element [ 'climont], significance [sig'mfikons], different (' dif (o) ront], physical [Tizikol], molecular [mo'lekjulo], evidence fevidons], cxccrcise feksosaiz], definite [ 'dcfinit] , experiment [iks'penmont], ncccssary fnesoson]

b) symbol, atomic, ease, simple, changc, exhibit, state, rubber, oxygen, show, three, only, pair, inert, avoid, written, also, catch, fire, while, since, way, how, thus, cause, news, world, truly, allow, place, cold, blue, line, pure

c) introduce [.inlro'djurs], acquire [a'kwaia], quantitative [ 'kwontitativ], either [' aido], neither [ 'naido], allotropy [o'lotropi], rather [* ro: do]

Ex. 2. Read the following words and say what Russian words help to understand their meaning:

symbol, publish, extraction, Latin, allotropy, molecular, metallic, associate, pair, inert, confusion, temperature, stable, combine, atom, element, modem

Ex. 3. Pay attention to the following way of word-building:

pre- + - , ,

prehistoric, prewar, pre-establish, premature, predetermine

post- + -

post-war, postposition, postgraduate

() + + + ()

aiiplanc, scawatcr, electromotive, electronegativity, shorthand, sidestep, sightseeing, old-time, manmadc, lifetime, diclcctropositive

Ex. 4. Find the meaning of the following words in a dictionary. If there is no word in your dictionary, find its parts and derive the meaning yourself.

old-fashioned, sidestep, sightsce, furthermore, water-like, therefrom, up-to-date, electropositive, electrostatic, water-proof, oxygen-rich

Ex. 5. Define what part of speech the italicized words belong to.

1. On account of their inactivity inert gases are often referred to as noble gases. 2. Some chcmical phenomena arc not easily accounted for.

3. Symbols began as a simple shorthand for the names of the elements.

4. Polonium was named in honour of Poland, the birthcountry of Marie Sklodowska-Curic. 5. At temperature below 0 C, water turns solid. 6. Some solids practically do not dissolve.

Text 12 A Chemical Symbols forElements

The Swedish chemist Berzclius (1779-1848) introduced the modern symbols for the elements when he published a list of "atomic weights" in 1818. Those elements which, on account of their case of extraction from their ores had been known from prehistoric times, were given symbols derived from their Latin names.

The symbols began as a simple shorthand for referring to the names of the elements, but rapidly acquired a quantitative significance. Pb began meaning "some lead", but it rapidly changcd and camc to mean cither "one atom of lead" or "one gram atomic weight of lead", i. e. 207 g of lead.

Some elements can exhibit allotropy; that is to say, they can exist in two different forms in the same physical state. Taking examples from among gaseous elements, ozone and molecular oxygen both contain only oxygen atoms, yet, the reactions of ozone are completely different from those of oxygen. It will immediately oxidize rubber and metallic silver, whereas oxygen will do neither. Evidence from gas-volume determinations shows that three atoms of oxygen are associated in ozone, whereas there are only two atoms in molecular oxygen. The atoms of all common gaseous elements exist in pairs except the inert gases. To avoid confusion, molecular gases are written 02, N2, Cl2and ozone Oj.

Some elements also exhibit allotropy; for example, white phosphorus catches fire in air at room temperature while red phosphorus is stable in air at 240 C. But since there is no way of discovering how many atoms arc combined together in any solid, the question is sidestepped, and all solid elements including allotropcs arc given symbols; thus, both white and red phosphorus are P rather than Px.

Words and Word-Combinations to Be Memorized

on account of, associate, avoid, come + ., completely, confusion, gaseous, either ... or ..., except, exist, extraction, include, introduce, list, molecular, neither, quantitative, rapidly, rather than , refer to, rubber, since, solid, stable, symbol, volume, yet

Ex. 6. Give the Russian equivalents for the following:

introduce smth., a list of "atomic weights", on account of, refer to the names of the elements, acquire a quantitative significance, cither ... or ..., exhibit allotropy, that is to say, exist in different forms , in the same physical state, take an example, from among gaseous elements, yet, be completely different, whereas, exist in pairs, avoid confusion, for example, catch fire in air, there is no way of, both ... and ..., rather than

Ex. 7. Give the English equivalents for the following:

, , ( ), , , ... ..., (- ), , , , .. . ..., , , , , , , , ...

Ex. 8. Fill in the blanks with prepositions where nccessary.

in, at, of, except, from, for, on account of

1. Bcrzclius introduced the modern symbols ... the elements ... 1818. 2. Some elements had been known ... prehistoric times ... their ease ...


extraction. 3. The symbols ... these elements were derived ... their Latin names. 4. There arc elements which can exist ... two different forms ... the same physical state. 5. Reactions ... ozone arc completely different ... those ... oxygen. 6. White phosphorus catches fire ... air ... room temperature. 7. The atoms ... all common gaseous elements exist ... pairs ... the inert gases.

Ex. 9. Supply the definite or indefinite article.

1. Mcndclcycv is ... famous Russian chemist. 2. Mendeleyev is ... founder of the Periodic Law. 3. Professor N is ... author of a great number of papers and books. 4. Swedish chemist Bcrzclius was ... great discovcrcr. 5. Do you know who ... discoverer of the atomic theoiy was? 6. Niels Bohr was ... Danish physicist. 7. Chemistry is ... branch of knowledge. 8. Section II is concerned with ... nature of radioactivity. 9. Dr. N discovered ... new law. 10. Faraday was ... well-known English physicist.

Ex. 10. Translate the sentences into Russian, paying attention to the predicates.

1. Chemistry concerns the compositions of matter and their transformations. 2. A great number of Russian scientists, among them Mendeleyev, Lomonosov, Butlerov ct al., Could be mentioned as contributors to the world science. 3. There arc several fields of chemistry in which Russian scientists have achieved significant progress. 4. The Periodic Law laid the foundation for the modern development of chemistry. 5. In the molten state metals are able to interact with one another. 6. Alloys which contain only two metals are referred to as bimetallic. 7. Science has become an important part of the modern world. 8. Chemists are needed almost in every field of life. 9. The theories and laws of chemistry are no less exact as those of physics. 10. Silicon, the fourteenth element in the periodic table might be called a congener of carbon, in Group IV. 11. Attempts to arrange the elements in a definite order were followed by a great discovery, the discovery of the Periodic Law. 12. The periodic table may be interpreted in terms of electronic structure of atoms. .13. Radioactivity was discovered by Henry Becqucrcl in 1896. 14. The change of the program of experimentation could have given more accurate results. IS. Before definite chemical evidence for the compound nature of a substance was obtained, the substance had been considered an clement. 16. In 1903 scientists recognized that radioactivity involves the spontaneous transmutation of elements. 17. Here we are going to give a detailed account of this phenomenon. 18. Heating was to have an important influence on the rate of the reaction. 19. Two points should have been determined: the composition of the sample and the relative weights of its constituent parts. 20. The result of the comparison may be completely the opposite. 21. The next step was to arrange the data in a table. 22. At any given temperature a molecule of a light gas such as helium or hydrogen will have the same average kinetic energy. 23. Chemists must have known a great number of

reactions that can procccd without catalysts. 24. Few chcmical reactions involve just a single elementary process. 25. We have prevented the formation of by-products. 26. New methods of investigation arc being developed, they arc much more effective than the older ones.

Ex. 11. Translate the sentences into English.

1. 1818 .

2. .

3. . 4. , . 5. . 6. - , -. 7. , :, N: . . 8. 240 . 9. , , .

Ex. 12. Make up questions to the italicized parts of the sentences.

1. The symbols began as a simple shorthand for referring to the names of the elements (3). 2. Ozone will immediately oxidize metallic silver (3).

3. There is no way of discovering how many atoms arc combined together in any solid (2).

Ex. 13. Answer the following questions:

1. What were the symbols introduced for? 2. Who introduced the symbols for chemical elements and when did he do it? 3. What significance did symbols acquirc? 4. What is the difference in writing allotropic modifications of elements?

Scction II

. 1. 12. , , , 12.

. 2. :

act, constant, composition, formula, experimentally, empirical, inorganic, crystalline, equivalent, sum, proportion, real, alternatively

. 3. . .

1. An empirical formula should be written with brackets (HgO)x. 2. Mendeleyev assumed (supposed) the existence of yet undiscovered elements. 3. Originally (at first) oxygen was callcd "inflammable air".

4. The symbol for mercury is Hg. 5. The law of constant composition was known, therefore (that is why) it was possible to use a formula for a compound. 6. The formula for ammonia is NH3. 7. A molcculc of a compound is defined (is dcscribcd) as die smallest part of a compound that can exist as a free and separate substance.


the very - ; equal - ; determine - ; relative - ; strictly - ; it makes no claim - ; perfectly - ; entity -

Text 12

( - 4 ).

Text 9 | Fluorine | Lesson 10 | Text 10 | Lesson 11 | Fascinating Phosphorus | Weight of 12 atom of carbon 12 | Lesson 13 | Text 13 A The History of Chemistry | Text 13 |

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