- •Раздел 2
- •1. Read this conversation and fill in the blanks. Use the best word or phrase from the list given below. Sometimes there is more than one possible answer.
- •2. Put the verb into the correct form, present continuous or present simple.
- •3. Put the verbs given in brackets into Present, Past or Future Simple. Sometimes you’ll need a negative form.
- •II. Modal verbs (модальные глаголы)
- •The Passive Voice (Пассивный/страдательный залог)
- •V. Четыре значения глагола то be
- •VI. Direct and Indirect Speech. (Прямая и косвенная речь)
- •VII. Неличные формы глагола (Non-finite forms of the verb)
- •1. Chemistry
- •2. Some facts about atoms
- •The measurements in chemistry
- •Liquids
- •5. Solid state
- •6. Elementary carbon
- •Hydrogen
- •8. Fuel
- •Слова и выражения, наиболее часто встречающиеся в научно-технической литературе
- •Тне united kingdom of great britain and northern ireland
- •Bashkortostan
- •The russian federation
5. Solid state
If you take a paper clip and bend it it would stay bent, it wouldn't, spring back and it wouldn't break. The metal of which the clip is made is ductile. Some other materials are not ductile at all. If you tried to bend a glass rod (unless you are holding it in a flame), it would simply break. It is brittle. In this respect as in many others, glass behaves quite differently from a metal. The difference must lie either in the particular atoms of which metals and glass are made up or in the way they are put together, probably both. There are of course many other differences between metals and glass.
Metals, for example, conduct electricity and therefore are used for electrical transmission lines, glass hardly conducts electricity at all and can serve as an insulator. Glass being transparent, it can be used in windows whereas a sheet of metal even more than a millionth of an inch thick is quite opaque. It is of course interesting to understand the reasons of these differences in behaviour.
During the past 20 years studies of this kind have been called solid-state physics, or sometimes since the subject Includes a great deal of chemistry, just "solid state". It is a major branch of science that has revealed new and previously unsuspected properties in metals. Solid-state physics has become one of the most important branches of technology. It has given rise to technological progress. Having studied this branch of technology, engineers could understand much better the phenomenon of quantum mechanics as it is applied to solids. Though solids, of course, were the subject of experimental investigation long before quantum mechanics was invented.
If we consider the faсt known sinсe the earliest studies of electric currents, we should remember that metals conduct electricity well and most materials do not.
It is only the discovery of electron that could help the scientists to understand some of these facts well. With the discovery of electron it was assumed that in metals some or all of the atoms had lost an electron and that in insulators such as glass they had not. The electrons in a metal proved thus to move freely, whereas the electrons in insulators do not. Why did this happen in metals? This very question had to await the discovery of quantum mechanics. The next question was "How are the electrons arranged?"
As far as this question is concerned we can say that solids can be divided into two clasps: crystalline and amorphous. In the crystalline group, which is the largest and includes the metals and most minerals, the atoms are arranged in a regular way.
6. Elementary carbon
Carbon occurs in nature in its elementary state in two allotropic forms namely diamond, this being the hardest substance known, and graphite, a soft, black crystalline substance used as a lubricant. Having investigated all the substances thoroughly the scientists found charcoal, coke, and carbon black to be microcrystalline or amorphous (non-crystalline ) forms of carbon.
Carbon burns to form gases: carbon monoxide, and carbon dioxide, the former being produced when there is a deficiency of oxygen or the flame temperature is very high.
This investigation followed by others resulted in new discoveries in the field of carbon. It has been found out that carbon monoxide is a colourless, odourless gas with small solubility in water. It is poisonous, because of its ability to combine the hemoglobin in the blood in the same way that oxygen does, and thus to prevent the hemoglobin from combining with oxygen in the lungs and carrying it to the tissues. It should be noted that the exhaust gas from automobile engines contain some carbon. Nevertheless carbon monoxide is a valuable industrial gas, for use as a fuel and as a reducing agent.
Carbon dioxide is a colourless, odourless gas with a weakly acid taste, due to the formation of some carbonic acid when it is dissolved in water. It appears to be about 50% heavier than air. It is easily soluble in water, one liter of water at 0°C dissolving 1,713 ml of gas under 1 atm pressure.
When crystalline carbon dioxide is heated from a very low temperature its vapour pressure reaches 1 atm at 79° at which temperature it vaporizes without melting. If pressure were increased to 2,5 atm the crystalline substance could be changed directly to a gas.
Carbon dioxide is known to combine with water to form carbonic acid. If you studied all the properties more thoroughly you would see that carbon dioxide is used for the manufacture of sodium carbonate, sodium hydrogen carbonate, and carbonated water and for many other uses.
From this short review it’s clear that chemistry of carbon and its compounds is a very important field of chemistry and should be studied carefully.