6. Ask the questions according to the model:

Model: He collects minerals. – Does he collect minerals?

What does he collect?

Who collects minerals?

1. The scientist work at a very actual problem nowadays. 2. They collect the samples of ores in the expedition. 3. On Fridays she doesn’t work with the students in the lab. 4. We attend lectures every day. 5. My cousin teaches inorganic chemistry at the University. 6. Formulas indicate chemical reactions. 7. Numerical subscript designates the number of atoms in the molecule.

7. Open the brackets choosing the correct form of the verb:

1. This scientist (work/ works/ doesn’t work) in the field of inorganic chemistry, he deals with organic compounds. 2. She (take part/ doesn’t take part/ will take part) as she (doesn’t have/ has/ have) no time. 3. He (attends/ attend/ doesn’t attend) lectures on Sundays. 4. I (am not work/do not work/ work) in this laboratory every day, as senior students (do/does) their experiments some days a week here. 5. Nobody (doesn’t/ doesn’t do/ does) this experiment without a respirator. 6. (Do/Does) anybody know these formulae? – No, nobody (does/doesn’t/do).

8. Read the text and learn how to read chemical formulas. Symbols, formulas and equations

Each of the 107 presently known chemical elements has a symbol. This symbol is usually derived from the name of the element. The symbol of oxygen is O, of hydrogen is H, of helium is He, of copper is Cu, of sodium is Na, of plutonium is Pu. Groups of symbols are called formulas. They are used to designate compounds. The formulae for water is H₂O, for carbon dioxide CO₂, for sulphuric acid H₂SO₄. These symbols and formulas are used to indicate chemical reactions. For example:

2 H₂O 2H₂+O₂

(Statement: Water decomposes to form hydrogen and oxygen)

9. How to read chemical formulas.

The symbols of chemical elements are read according to the names of English alphabet letters.

The sign “+” is read as plus, and, together, with, react with.

The sign “-“ indicates one relation and isn't read at all.

The sign “=” is read as give, form or produce.

T he sign “ “ is read as give, pass over to or lead to.

T he sign “ ” is read as forms and is formed from.

2H₂O – a figure before an element signifies the number of molecules; two molecules of water.

2 H₂+O₂ 2H₂O

Two molecules of H two plus O two give two molecules of H two O or Two two-atom molecules of hydrogen react with one two-atom molecule of oxygen and produce two molecules of water.

N ₂+3H₂ 2NH₃

N two plus three molecules of H two form and are formed from two molecules of NH three or one two-atom molecule of nitrogen plus three two-atom molecules of hydrogen form and are formed from two molecules of ammonia.

N a₂CO3+CaSO₄ Na₂SO₄+CaCO₃

Na two Co three plus CaSO four form Na two SO four plus CaCO three or the sodium (Na) and the calcium (Ca) switch places. The sodium combines with the sulphate radical (SO₄), forming sodium sulphate (Na₂SO₄) which dissolves in water. The calcium combines with the carbonate radical (CO₃), forming calcium carbonate (CaCO₃). Calcium carbonate does not dissolve in water and so settles to the bottom of the solution.

10. Train to read the names of the compounds.

carbon dioxide, sulphuric acid, nitrogen oxide, hydrogen chloride, calcium carbonate, sodium sulphate, natrium nitrite, hydrocarbon, calcium bromide, lithium fluoride, aluminium carbide, nitric acid, sulphurous gas.

11. Now you can name the compounds by yourself:

HCl, Co₃, H₂SO_4, ZnSO_4, CaCl_2, 2P₂O₅, CuO, NaNO_3, NaHSO₄

12. Answer the questions to the text:

1. How many chemical elements are presently known?

2. What are symbols usually derived from?

3. What are groups of symbols called?

4. What is the formula for sulphuric acid?

5. What does water form when it decomposes?

13. Explain the meaning of the verb "to do" in the following sentences:

1. What do you usually do in the laboratory? 2. He will do his best to finish his work in time. 3. Among the gases with which mercury does react is hydrogen sulphide. 4. The substance does support com­bustion. 5. Gold does not combine with oxygen or with sulphur and does not react with any familiar acids. 6. It does, however, combine with chlorine and bromine. 7. Copper does not displace hydrogen from acids, but does react with acidic oxidizing agents. 8. They did carry out this work in due time. 9. They did their last task very well though it was rather difficult. 10. They always do everything in due time. 11. Do you know that a quite new property of this substance was observed?