1. Translate the following sentences into Russian:

1. Methane also is known as marsh gas because some bacteria in swamps can oxi­dize hydrogen, using C0₂ rather than 0₂, to yield methane and water.

2. The larger the hydrocarbon molecule, the stronger are the van der Waals forces between molecules, and the higher the temperature needed to melt the solid or vaporize the liquid.

3. Hydrocarbons that have double or triple bonds between carbon atoms are called unsaturated hydrocarbons.

4. The halogen derivatives are not important for their own sake, but because they are a bridge to other, more useful compounds.

5. If an initial heat supply is provided to start the process, then the heat given off by oxidation is enough to keep the reaction going.

6. Alkenes also link together or polymerize into long chains -a reaction that is of great importance in plastics and rubbers.

7. Polyvinyl chloride chains are used for phonograph records and plastic pipe, and with the addition of a plasticiser, as artificial leather.

1. Cross-linking of polymer chains is a standard method today of producing a hard, mechanically strong plastic or resin.

2. Delocalization can occur whenever single and double bonds alternate along a chain of atoms, so that after all single bonds are formed, each atom along the chain has an unused p orbital and one unused electron.

1. Translate the following information into Russian:

These molecules are useful in photosynthesis because they help the plant or bacte­rium to absorb and harvest light energy.

The relationship between the extent of delocalization and wavelength of light ab­sorbed spirilloxanthin, and isorenieratene have successively larger delocalized systems,

2. 13, and 15 electron pairs, respectively.

Their electronic energy-level spacings therefore become progressively smaller, as diagrammed within the properties table.

The three molecules absorb in the blue-violet, the green, and the purple-red regions of the visible spectrum, respectively, so the molecules are coloured yellow-orange, pur­ple, and green by the unabsorbed wavelengths.

Р-Carotene occurs in all green plants (usually masked by the green of chlorophyll), and is responsible for the yellow colour of carrots, tomatoes, and autumn leaves.

Spirilloxanthin and isorenieratene give purple and green photosynthetic bacteria their characteristic colours.

Simple aliphatic molecules with unconjugated double bonds react quickly with bromine or chlorine to form saturated, dihalogenated molecules:

If the Kekule’ structure for benzene were correct, one would expect the same rapid halogenation reaction:

This is not what happens at all. The reaction is slow, and only results in the substi­tution of first one and then two bromine atoms for hydrogens around the ring, with the delocalized ring structure remaining intact. Hence aromatic molecules have a slowness to react that is more like the behaviour of alkanes than alkenes.

As with the straight-chain hydrocarbons, so with aromatic molecules. The easiest chemical derivatives to prepare are the chlorides and bromides. These are the gateways to the great variety of organic compounds that are the subject of the next chapter.