Inorganic molecules and compounds

Read and translate the text

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 dohis 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 notcombine with oxygen or with sulphur and does not reactwith any familiar acids. 6. It does, however, combine withchlorine 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. Doyou knowthat a quite new property of this substance was observed?

Simple diatomic molecules of a single element are designated by the symbol the element with a subscript 2. That indicates that the element contains 2 atoms. Thus the hydrogen molecule is H₂; the nitrogen molecule, N₂; and the oxygen molecule, O₂. Polyatomic molecules of a single element are designated by the symbol for the element with a numerical subscript corresponding to the number of atoms in the molecule. Examples are the phosphorus molecule, P₄, and the sulphur molecule, S₈.

Diatomic covalent molecules, containing unlike elements, have a similar designation. The formula for hydrogen chloride is HCL. The more electropositive element is always designated first in the formula.

For polyatomic covalent molecules containing unlike elements, numerical subscriptions are used to designate the number of atoms of each element present in the molecule, for example, water, H₂. Again, as in diatomic molecules, the more electropositive element is placed first in the formula.

Notes to the text:

numerical– числовой

corresponding– соответствующий

unlike– различный

16. Find the pairs of the words with the opposite meaning:

single-atomic, first, less, unlike, absent, simple, compound, similar, more, polyatomic, present, last.

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