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Read and translate the text. Chemistry is the study of substances




CHEMISTRY


Chemistry is the study of substances. Chemists investigate properties of the substances that make up the universe and how these substances behave under different conditions. They attempt to explain the behavior of a substance in terms of its structure and composition. Chemists also seek to understand chemical changes. These changes involve alterations in the chemical makeup of a substance. The com combination of iron with oxygen from the air forming rust is a chemical change. Substances may also go through physical changes without altering their chemical makeup. Water changes physically but not chemically when it freezes.

Chemists have learned much about the chemical substances and processes that occur in the nature and have created many useful substances that do not occur naturally, so they have greatly improved peoples lives.


Chemistry studies many substances. Substances differ greatly in properties, structure, and composition. The methods chemists use and the questions they attempt to answer also differ greatly.

The most basic chemical substances are the chemical elements. They are the building blocks of all other substances. Each chemical element is made up of only one kind of atom. There are 91 elements known to exist on the Earth. Additional 20 elements have been produced artificially. Electrical forces at the atomic level create chemical bonds that join two or more atoms together, forming molecules. Some molecules consist of atoms of a single element. When atoms of two or more different elements bond together, they form a chemical compound. Water is a compound of two hydrogen atoms and one oxygen atom. Compounds are formed or broken down by means of chemical reactions. All chemical reactions involve formation or destruction of chemical bonds.

Chemistry comprises the following sciences.

Analytical chemistry determines the identity and quantity of each element or compound present in a substance. Qualitative analysis is concerned with identifying the kinds of elements or compounds in a sample. Quantitative analysis indicates the amounts of the elements present. The techniques of analytical chemistry include the use of the spectroscope, mass spectrograph, X-ray tube, ultraviolet fluorescence, and radioisotopes.

Biochemistry is the study of the chemical composition of living matter and of the chemical processes that occur in living organisms. This field is particularly important in agriculture, biology, bacteriology, pharmacology, medicinc, and dentistry.

Chemical engineering is a combination of chemistry and engineering that develops or improves industrial processes for making commercial amounts of desirable chemicals that have been produced only in small quantities or in the laboratory.

Colloid chemistry is the study of the behavior of matter particles that are larger than ordinary molecules but smaller than objects that can be seen with the best optical microscope. Particles in this size range (10 to 2.000 A in diameter) have many unique properties. The tools used in this field include the ultracentrifuge, ultramicroscope, and electron microscope.

Electrochemistry is the study of chemical reactions that are produced by or produce an electric current. Also studied are the electrical conductivity of solutions and the phenomena that occur at electrodes application. Electrochemistry provides methods for chemical analysis and production of chemicals by electrical means.

Inorganic chemistry is the study of all elements and compounds that do not contain carbon. These include metals, halogens, and alkalies.

Nuclear chemistry is the study of radioactivity, atomic nucleus, and nuclear reactions, and the development of applications for radioactive isotopes in medicine and industry.

Organic chemistry is the study of carbon and its compounds. Carbon compounds account for about 96 percent (about six and one-half million) of all known compounds. Among the carbon compounds studied by organic chcmists arc plant and animal tissues, petroleum, carbohydrates, proteins, plastics, and rubber.

Physical chemistry is the application of physical methods to the study of chemical problems. Included in this field are atomic and molecular structure; theory of reaction rates; mechanism of reactions; chemical equilibriums; energy changes in reactions; theories of solids, liquids, gases, plasmas, and solutions; electrochemistry; radioactivity.

IV. Language development.

1. Fill in the gaps with the words from the list.

properties, alteration, occur, comprise, quantity, bond, join, particle, unique, reaction, solution, equilibrium

1. All the chemical elements differ by their physical and chemical

2. The... of mercury with water may lead to very negative consequences.

3. Natural... was destroyed because of government experiments with ecosystems.

4. This specimen is..., I have never seen anything like this.

5. Two these elements have ionic..., that is why they together form a very stable complex substance.

6. Be very careful when you work with... of hydrochloric acid, you can burn yourself.

7. When different elements bind together, they undergo chemical....

8. The science of chemistry... many different but nonetheless very important fields.

9. When a pharmacist is preparing a drug, he must think not only of..., but of quality too.

10. As a result, many subsequent changes may....

 

2. Answer the following questions.

1. What is chemistry?

2. What do chemists study?

3. What are chemical changes?

4. What is the difference between chemical and physical changes?

5. How do chemical elements differ from each other?

6. How many elements arc there on the Earth: natural and artificially synthesized?

7. What is analytical chemistry? Why is it important to study quantitative and qualitative analysis?

8. What professions is biochemistry especially important for?

9. What tools are used in colloid chemistry?

10. What is the difference between organic, inorganic chemistry and biochemistry?

V. Speaking.

1. Make questions for the answers. Then, in pairs, act out the dialogue.

- _____________________________________________________?

- Chemistry is the study of substances.

- _____________________________________________________?

- There are many fields of chemistry, analytical chemistry, biochemistry, chemical engineering, organic and inorganic chemistry, electrochemistry.

- ____________________________________________________?

- Analytical chemistry determines the identity and quantity of each

element or compound present in a substance.

- ____________________________________________________?

- Biochemistry is the study of the chemical composition of living matter and of the chemical processes that occur in living organisms.

- _______________________________________________________?

- Inorganic chemistry is the study of all elements and compounds that do not contain carbon. These include metals, halogens, and alkalies. Organic chemistry is the study of carbon and its compounds.

- ________________________________?

- Nuclear chemistry is the study of radioactivity, atomic nucleus, and nuclear reactions, and the development of applications for radioactive isotopes in rncdicine and industry.

- __________________________________________________________?

- Physical chemistry is the application of physical methods to the study of chemical problems.

2. Give as much information as you can about:

fields of chemistry;

possibilities of career in different fields of chemistry;

modern branches of chemistry like biochemistry and chemical engineering.

 

 

Organic Chemistry.

.

I. Active vocabulary.

hydrocarbon ;

tetravalent ;

leucine.. ;

methionine ;

albumin ;

convert ;

inulin ;

carbohydrate ;

greasy ;

triglyceride ;

hydrolysis ;

phospholipid ;

lecithin ;

glycogen .





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