D.I. Mendeleyev and his discovery

1. The story of how D. I. Mendeleyev established the Periodic System of Elements has long been a matter of great interest to research workers.

2. When Mendeleyev began to teach at St. Petersburg University, chemistry was still far from being the well-ordered and harmonious branch of science that we know today.

3. The great majority of scientists were firmly convinced that atoms of different elements were in no way connected with each other, and that they were quite independent particles of nature. Only a few advanced scientists realized that there must be a general system of laws which regulates the behaviour of atoms of each and every element. However, the few attempts made by Beguyer de Chancourtois, Newlands, Lother Meyer and others to find a system of laws controlling the behaviour of atoms were unsuccessful and exercised no influence on Mendeleyev, the future founder of the Periodic System of Elements.

4. "Mendeleyev was a man who could not bear any kind of disorder and chaos," writes Academician A. A. Boikov. "This is why at the beginning of his course in chemistry at St. Petersburg University, where he had been appointed to the department of chemistry, D. I. had to establish order in the chemical elements."

5. By comparison of chemical properties of different elements researchers had long ago discovered that elements could be placed in several groups according to similarity in their properties.

6. Mendeleyev applied in his system the principles that he developed and included in his table the listing of the elements according to increasing weights.

7. Because he had the insight to see that many elements had not yet been discovered, he left open spaces in the Periodic Table. For example, he predicted that an unknown element with atomic weight of 44 would be found for the space following calcium. And in 1879 the Swedish chemist Lars Fredric Nilson discovered scandium.

8. Mendeleyev's table developed into the modern Periodic Table, one of the most important tools in chemistry. The vertical columns of the modern Periodic Table are called groups and the horizontal rows are called periods. The atomic number of an element is the number of protons in the nucleus of the atom of that element. The modern Periodic Table not only clearly organizes all the elements, it lucidly illustrates that they form "families" in rational groups, based on their characteristics.

VII. Ответьте на вопросы к тексту

1. When and where was D.I. Mendeleyev born?

2. What subjects did he like?

3. What problems was Mendeleyev interested in?

4. Why did Mendeleyev have to establish order in the chemical elements?

5. What are periods / groups?

6. How are "families" formed?

VIII. На основе текста составьте тему “ D.I. Mendeleyev and his discovery”

ВАРИАНТ IV

I. Перепишите и переведите следующие предложения. Определите, какой частью речи являются слова с окончанием -s и какую функцию это окончание выполняет, т. е. служит ли оно:

− показателем 3-го лица единственного числа глагола в Present Simple;

− признаком множественного числа имени существительного:

− показателем притяжательного падежа имени существительного

1. Mendeleyev's greatest discovery was the Periodic Law.

2. The assistant makes these experiments every week.

3. Some of the properties of this substance will be predicted.

II. Перепишите и переведите следующие предложения, учитывая особенности перевода определений, выраженных именем существительным

1. Accurate pressure characteristics are very important for this chemical process.

2. Lavoisier also contributed greatly to the organization of chemical data, to chemical nomenclature, and to the establishment of the mass conservation law.

3. They must pay much attention to the problem of laboratory ventilation.

III. Перепишите следующие предложения, содержащие разные формы сравнения и переведите их

1. It is much heavier than the air and may be passed through a glass tube to the bottom of the bottle.

2 Modern laboratories of inorganic as well as of organic and analytical chemistry are provided with gas and running water.

3. He is the best specialist in his field.

IV. Перепишите и переведите предложения, обращая внимание на неопределенные и отрицательные местоимения

1. There are some dangerous chemical substances.

2. As Mme. Curie had examined every known chemical element and none of them had emitted such powerful rays as pitchblende she could only decide that this mineral must contain some new element.

3. No progress is possible without new discoveries in this field.

V. Перепишите следующие предложения, определите в них видовременные формы глаголов и укажите их инфинитив, переведите предложения

1. A unique conveyer system simplifies the machine parts assembly.

2. They paid much attention to the problem of laboratory ventilation.

3. This kind of control will help to operate the production process.

VI. Прочитайте и устно переведите текст

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