Read and translate.

NITROGEN

Nitrogen is a colourless, odourless, tasteless diatomic gas constituting about 4/5 (four fifths) of the atmosphere by volume. It is slightly soluble in water and in alcohol. Nitrogen is the 17^th most abundant element of the Earth’s crust. There it is found in mineral compounds, such as saltpetre (KNO₃) and soda nitre, or Chile saltpetre (NaNO₃). Compounds of nitrogen are essential constituents of all living organisms. The proteins and nucleic acids in particular are basic building blocks of all living life forms.

Nitrogen forms a series of oxydes and oxyacids. The most important of them is nitric acid, HNO₃. It also unites with hydrogen to form ammonia, NH₃. With many of the metallic elements it forms nitrides.

The organic compounds of nitrogen, however, are more numerous and variegated than the inorganic ones. They include the amines or substituted ammonia; the nitro series to which many explosives belong; the amides, e.g. nylon; the dyestuffs, and a wide variety of other chemical compounds.

Notes to the text:

to constitute– составлять alcohol– спирт abundant– обильный essential– существенный protein– белок amine– амин amide–амид dyestuff– краситель

saltpetre– калиевая селитра soda nitre– природная селитр chile saltpetre– чилийская селитра nucleic acid– нуклеиновая кислота oxyacid– кислородная кислота substitude– замещать nitro series– нитросерии

18. Characterize any gas you know according to the plan:

a) characteristics; b) properties; c) occurring; d) usage.

19. Read these short texts and guess what substances they are about:

1. It is typical non-metallic substance. This substance as well as oxygen has six electrons on the outer shell and needs two more to fill the shell. It undergoes both oxidation and reduction. It exists at least in two crystalline forms. It’s an amorphous material. Being amorphous it doesn’t crystallize at all. It unites with oxygen and common metals, except gold and platinum. It is in the group VI of the Periodic Table.

2. It is the most abundant element found in the earth’s crust. It’s grey-blue metalloid with metallic lustre. It’s very brittle. The element is usually tetravalent in its compounds. It forms a great variety of both organic and inorganic compounds. It crystallizes in the diamond lattice, has a specific gravity of 2.42, melts at 1,420°C and boils at 3,500°C. Being elementary it is used as an alloying constituent to strengthen aluminium, copper and other metals.

3. It’s a greenish diatomic gas. It is one of the strongest oxidizers. It is never found free in nature, but only in its minerals. It combines with almost all elements except inert gases as argon, neon and helium. It’s soluble in water. This gas is poisonous as the acid which it forms. This is the only acid corroding glass. The main use of the element described is synthesis of polymers.

Дата добавления: 2015-12-01