The Nuclei of Atoms

In 1911 the British physicist Ernest Rutherford carried out some experiments which showed that every atom contains, in addition to one or more electrons, another particle, called the nucleus of the atom.

Every nucleus has a positive electric charge. It is very small. It is about as big as an electron. It is very heavy.

There are many different kinds of nuclei. The nuclei of the atoms of one element are different from the nuclei of the atoms of every other element.

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Тема 8. Види вимірювань в хімії.

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План заняття

І Організаційний момент. Привітання

The Measurements in Chemistry

Ex. 1 Прочитайте речення швидко

1. We studied the measurements in chemistry. 2. This is the one type of measurement. 3. The microscope is an instrument for making very small objects look larger. 4. The fundamental unit of the metric system is the metre.

Ex. 2Вставте" to have to", " to be to", " must"

1. The experiment,.. take place on Monday, I think everything is ready. 2. They... examine this sample under a very powerful microscope as it is very small. 3. I am very tired, I... have a rest. 4. Our meeting... take place after our last lecture. 5. You... work hard if you want to finish this work. 6. I... go to the reading-room as I have no books at home. 7. He... wait for two hours as his train has just left. 8. All the students of our Institute... carry out a number of experiments in analytical laboratory.

Ex. 3. Вставте" " can", " could", " to be able to";

1. If you come earlier, I... help you. 2. This solution,.,. be evaporated now. 3. Yesterday he... finish his experiment, I think he... do it today. 4. As he was very busy he,.. attend the lecture.

Ex. 4 Перекладіть речення.

1. Since we know all the properties of the substance, we can use it in our experiment. 2. Many interesting investigations have been done since the foundation of this research laboratory at our plant. 3. Helium belongs to the same group as argon since it does not combine with other elements. 4. I have not carried out any experiments in the laboratory sinceI graduated from the Institute. 5. We couldn't finish our work since we had no necessary devices. 6. Since the kinetics of the reaction was studied at room temperature, the results were good. 7. This element has been known since the 19th century.

Ex. 5Перекладіть речення.

I. D. I. Mendeleyev arranged the elements in the order of increasing atomic weights. 2. In order to be used in a chemi­cal laboratory natural water must be purified. 3. The order was announced at the meeting. 4. In order to dissolve this sub­stance one must heat it. 5. The students must put everything in order when they finish their work. 6. In order to study the relationship between microstructural and mechanical prop­erties of the gel, it is very important to use pure stable gels

. Ex. 6 Перекладіть слова

close relationship, exact measurement, quantitative analysis, necessary method, the order of arrangement

THE MEASUREMENTS IN CHEMISTRY

In order to understand the quantitative relationships which exist between various kinds of matter, the chemist who is interested in matter and the changes which it undergoes, has to measure the quantities of matter with which he works, that is since mass is the measure of the quantity of matter, he is to measure mass. The measuring device the chemist is to employ in this determination should be the balance.

Since for every chemical change there is always accompanying energy change which the chemist has to take into account, the calorimeter and the thermometer have to be used.

The chemist usually employs graduated cylinders, burettes, pipettes and volumetric flasks for the measurements of volumes of liquids, and the gas burette for the measurement of volumes of gases.

The chemist employs the barometer if he has to measure the pressure.

The analytical chemist and the physical chemist employsuch devices as calorimeters, polarimeters, refractometers and a number of electrical devices.

If the chemist is to examine very small samples of matter, he should use a microscope. The microscope is an instrument which by the combination of lenses permits man to see objects which are too small to be seen with a naked eye. It is an instru­ment which is useful in many sciences and which, although more frequently used in a qualitative way, can also be used quantitatively.