Before reading the text make sure whether you understand these word-combinations correctly

related elements, missing element, relation between the atomic weights and physical and chemical properties, in the way now described by, very close to, the alkaline-earth metals, successive turns of the helix, values of the atomic weights, in the order of increasing atomic weight, replaced by the "long-period" form, equal to the ordinal number of the element, success verified by experiments, in the inverted order of atomic weight.

4. Find the sentences in which the word with the ending "-ed" is a part of the Passive Voice:

1. They produced some new alloys at our plant. 2. This new material was produced at our plant. 3. He carried out his first experiments abroad. 4. This research work is being carried out by our students. 5. D.I. Mendeleyev formu­lated the Periodic Law. 6. This law opened new prospects in organic chemistry. 7. The articles written by our English colleges were soon translated into some languages. 8. He was appointed Professor of the Physico-Chemical department. 9. All the samples will be carefully examined. 10. The work was presented in time.

5. Find the correct translations of the following English sentences:

1. The professor was asked many questions by the students after the lecture.

a) Профессор задал студентам много вопросов после лекции.

b) После лекции профессору задали много вопросов.

c) Профессору задали много вопросов студенты после лекции.

d) После лекции студенты задали профессору много вопросов.

2. Chemistry is taught at our Institute by a well-known scientist.

a) Химия преподается в нашем институте известным ученым.

b) Известный ученый читает (преподает) курс химии в нашем институте.

6. Use the Passive Voice according to the model:

Model: A. Will you use this solvent in your work?

B. No, it has already been used.

1. Will he explain this new method to them? 2. Do you want to find out the melting point of this substance? 3. Will they evaporate this solution? 4. Is he going to translate this article this week? Are you going to experiment with these acids? Will they continue their research work of this oil deposit?

7. Translate the following sentences paying attention to the Passive Voice constructions:

1. Physics and chemistry are taught at school. 2. Some of the experiments were carried out in our Institute. 3. Some of the properties of this substance will be predicted. 4. He was appointed Rector when he was 35 years old. 5. Almost all branches of chemistry and physics will be enriched by this new theory. 6. I was told about that great chemist who devoted his life to chemistry. 7. The professor was asked many questions after the lecture. 8. He was sent abroad to contin­ue his studies. 9. This problem is dealt with in many textbooks. 10. This article will be presented as soon as we finish it. 11. This problem is being discussed by many scientists both in our country and abroad. 12. Some new results were obtained by a group of research workers. 13. This substance cannot be used, it has many impurities.

Warming-up:

1. Was D. Mendeleyev really the first who systematized elements?

2. Could you name scientists classified elements earlier?

3. When/ what time did scientists begin to classify substances?

8. Read the text below and add your answers with the necessary details.