PART vii. SPEAKING

Exercise 1. Finish sentences with two or more sentences.

1. Toxic substances can be classified into several categories according to ….

2. The amount of water in the body depends on ….

3. The average Na+ intake is about … and excess sodium intake may result in ….

4. There are some important organic chemicals that are essential to health. For example ….

5. Sulphuric acid is the chief basic chemical in many countries. Other basic chemicals include ….

Exercise 2. Agree or disagree with the following statements. Use the phrases: Yes, I fully (partially) agree; That’s quite right; I think so; Right you are; I disagree; I’m afraid; That’s wrong; Just on the contrary.

1. D.I. Mendeleev was the only one who contributed to the development of the Periodic Table of elements.

2. List of elements are available by name, by symbol, by atomic number, by density, by melting point, and by boiling point.

3. There is no much difference between chronic and acute poisoning.

4. Lethal doses of toxic substances are usually expressed in grams.

5. The exact amount of water in the human body depends upon age, sex and build of a man.

Exercise 3. Fulfill the following tasks:

a) Enumerate:

- elements used by ancients;

־ elements discovered by chance;

־ toxic elements and their possible effects.

b) Indicate:

- elements contained in a man;

־ functions of minerals in the body.

c) Briefly indicate: contribution to the development of chemistry made by Antoine Lavoisier, Marie Scladovska Curie, D. I. Mendeleev and other scientists.

Exercise 4. Look through

a ) the “Table of elements and their discoverers” in the Appendix part of the textbook. Tell your group mates during what century the greatest number of elements were discovered and scientists from what countries contributed mostly to the discovery of elements. Names of what scientists are well-known to you?

b ) the list of elements in Appendix part of the textbook and chose any of it. Think of its description and present it to your group mates to guess the name of the element described.

Exercise 5. Give some facts proving that:

1. Heavy metals are very toxic and should be used with caution.

2. Oxygen is one of the elements present in the human body in the greatest amounts.

3. Certain organism may accumulate considerable amounts of elements that do not occur in the human body.

4. Not only chemical elements are considered as toxic.

5. Chemical substances affect the human body in different ways.

6. Elements may serve man in his everyday life.

Exercise 6. Extend the idea. Express your point of view. Use the following phrases: I think/feel that …. As far as I know …. My point of view is ….

1. Chemists sometimes speak about chemical changes and physical changes.

2. Nearly all elements on or in the earth are found combined with other elements.

3. Artificially combined elements are not plentiful; all of them are radioactive.

Exercise 7. Prepare a talk about chemical elements using the following points as a plan.

1. Periodic table of elements as the first natural classification of chemical elements and its significance to further development of chemistry.

2. Properties of matter.

3. Chemical elements of living matter and their amount.

4. Classification of toxic substances and their action.

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