In 180S the English chemist and physicist John Dalton (1766-1844) put forward the hypothesis according to which all substanccs were stated to consist of small particles of matter, of several different kinds, corresponding to the different elements. He called these particles atoms, from the Greek word atomos, meaning "indivisible". This hypothesis gave a simple explanation or picture of previously observed but unsatisfactorily explained relations among the weights of substances taking part in chemical reactions with one another. As it was verified by further work in chemistry and physics, Dalton's atomic hypothesis became the atomic theory.
The rapid progress of scicncc during the twentieth ccntury is well illustrated by the increase in our knowledge about atoms. In a popular textbook of chemistry written in the early years of the twentieth century, atoms were defined to be the "imaginary units" of which bodies arc aggregates. The article in "Atom" in the 11 th edition of the Encyclopaedia Britannica, published in 1910, ends with the words "The atomic theory has been of priceless value to chemists, but it has more than once happened in the history of science that a hypothesis, after having been useful in the discovery and the coordination of knowledge, has been abandoned and replaced by one more in harmony with later discoveries. Some distinguished chemists thought that this fate may be awaiting the atomic theory... But modern discoveries in radioactivity are in favour of the existence of the atom, although they lead to the belief that the atom is likely to be not so eternal and unchangeable a thing as Dalton and his predecessors had imagined".
Only half a ccntuiy later, scientists had precise knowledge of the structure and properties of atoms and molecules. Atoms and molecules can no longer be considered "imaginary".
Words and Word-Combinations to Be Memorized
article, current, define, distinguish, explanation, in favour of, illustrate, increase, no longer, more than once, physicist, physics, popular, precise, previously, price, priceless, progress, put forward, radioactivity, rapid, replace, satisfactory, useful, be of value
Ex. 5* Give the Russian equivalents for the following:
put forward a hypothesis, according to the atomic theory, give an explanation, previously observed relations, by further work, rapid progress, during the current ccntury, be illustrated by smth., imaginary units, be of value, replace a hypothesis by a theory, a distinguished chemist, discoveries in radioactivity, be in favour of smth., imagine, have precise knowledge, no longer
Ex. 6. Give the English equivalents for the following:
выдвинуть идею, согласно теории, дать простое объяснение, объяснить факт, принять участие в реакции, друг с другом, популярная книга, третье издание, опубликовать статью, заменить одну идею другой, выдающийся ученый, доводы в пользу гипотезы, спустя полстолетия, больше не может рассматриваться, увеличение радиоактивности, не один раз, ранее неизвестная величина, быстрое развитие
Ex. 7. Fill in the blanks with prepositions where necessary.
1. Dalton's theory was put... 180S. 2. The hypothesis could not explain ... relations... the weights... substanccs taking part... chemical reactions. 3. The atomic theory is ... priceless value ... chemists. 4. Modern discoveries ... radioactivity arc ... the cxistcncc ... the atom. 5. Half... a ccntury later the atomic structure became clear. 6. The atomic theory is useful ... the coordination ... knowledge. 7. Dalton's atomic hypothesis was verified ... further work ... chemistry and physics.
Ex. 8. Translate the sentences into Russian paying attention to different functions of/br.
1. The atomic theory was of great value for further development of scicncc. 2. Dalton's hypothesis became the atomic theory, for it was verified by later discoveries. 3. For this reason the hypothesis 4vas replaced by another one. 4. This technique is recommended to be used, for it is very accuratc. 5. Argon and other gases of this group arc callcd inert, for they are chemically inactive. 6. The theory hasn't been recognized for almost a century.
Ex. 9. Translate the sentences into Russian.
a) 1. Dalton's hypothesis was later proved to be true. 2. Fundamental particlcs arc no longer considered to be non-existent. 3. Radioactivity is known to be afTcctcd by the presence of other elements which arc not radioactive. 4. Air was later found not to be an element. 5. Hydrogen does not appear to react quickly with chlorine in the dark. 6. Pure liquid HCI docs not seem to be conductor of electricity. 7. Under certain conditions an atom of hydrogen may be regarded to be acting as a bond. 8. There appears to be no difficulty in determining the rate of this reaction. 9. There seems to be no evidence in favour of your idea. 10. The phenomenon has never been observed to occur under ordinary conditions. 11. Chlorine is stated to have been discovered in 1774.12. Solid carbon is usually said to exist in three modifications. 13. Mendeleyev is known to have been born in Tobolsk. 14. The law of conservation of mass is known to have been definitely stated by the great Russian scientist M. V. Lomonosov in 1756. 15. H2SO4 docs not appear to have been known to the ancient world.
b) 1. The symbol H2S04 is interpreted as representing one molecule of sulphuric acid. 2. Acids arc usually diought of as being liquids. 3. According to the atomic theory, a molcculc is considered as being composed of atoms. 4. The periodic classification should be mentioned as having been the principal discovery of the 19th ccntury. 5. A nucleus is now regarded as being composed of fundamental particles. 6. AH substances may be regarded as soluble in water. 7. Atoms arc no longer considered "imaginary". 8. The valency of carbon is usually thought of as four. 9. Water is known as composed of two elements: hydrogen and oxygen. 10. Substances arc usually defined as having a definite composition.
Ex. 10. Translate the sentences into English.
1. Джон Дальтон был химиком и физиком. 2. Он жил в Англии с 1766 по 1844 год. 3. Более всего он известен свосй атомистической теорией. 4. Дальтон выдвинул свою теорию строения элементов в 1805 году. 5. Эта теория была подтверждена дальнейшими исследованиями. 6. Позднее она была развита в соответствии с современными исследованиями. 7. Современная наука располагает точными знаниями о структуре и свойствах атомов и молекул. 8. Теперь никто больше не может утверждать, что структура и состав атомов неизвестны.
Ex. II. Answer the following questions:
1. When was Dalton's atomic hypothesis put forward? 2. What was the main idea of this hypothesis? 3. In what way was the hypothesis verified? 4. What docs sometimes happen to a hypothesis in the course of history? 5. Was Dalton's hypothesis forgotten later? 6. What do modern scientists think about Dalton's theory?
Section II
Упр. 1. Назовите значения следующих интернациональных слов:
electronic, arc, refract, diffract, line, spectrum, progress, interpretation, regularity, especially, physicist, quantum, problem, extraordinary
Упр. 2. Определите значения выделеиных слов по контексту.
1. Hertz is a unit offrequency. 2. The discovery of the atomic structure laid the basis for further discoveries in science. 3. The measurements must be made very carefully. 4. Heat and light arc often emitted during the reaction. 5. When we use some example in our work, one can say that we work according to a pattern.
Сюва к тексту:
excite—возбуждать; spark—искра; distinctive—отчетливый; achieve — достигать; successfully — успешно; advance — улучшение, прогресс