Some Facts about Chemistry

Chemistry has two main aspects: 1) descriptive chemistry, dealing with the discovery of chemical facts; 2) theoretical chemistry, describing the formulation of theories.

The broad field of chemistry may also be divided in other ways. No one person could expect to master all aspects of such a vast field, so it has been found convenient to divide the subject into smaller areas. For example:

Analytical chemistry is that field of chemistry concerned with the identification of materials and with the determination of the percentage composition of compounds and mixtures. These two lines of research are known, respectively, as qualitative analysis and quantitative analysis. Two of the oldest techniques used in analytical chemistry are gravimetric and volumetric analysis. New analytical procedures often discover the presence of previously unknown compounds. Gravimetric analysis refers to the process by which a substance is precipitated (changed to a solid)

out of solution and then dried and weighed. Volumetric analysis involves the reaction between two liquids in order to determine the composition of one or both of the liquids. In the last half of the twentieth century, a number of mechanical systems have been developed for use in analytical research. For example, spectroscopy is the process by which an unknown sample is excited (energized) by heating or by some other process. The radiation given off by the hot sample can then be analyzed to determine what elements are present. Various forms of spectroscopy are available (X-ray, infrared,

Computer-generated model of a 60-carbon molecule enclosing a potassium ion. The 60-carbon molecule, called a buckminster-fullerene, was discovered by organic chemists in 1985. (Reproduced by permission of Photo Researchers, Inc.)

and ultraviolet, for example) depending on the form of radiation analyzed.Other analytical techniques now in use include optical and electron microscopy, nuclear magnetic resonance (MRI; used to produce a three-dimensional image), mass spectrometry (used to identify and find out the mass of particles contained in a mixture), and various forms of chromatography (used to identify the components of mixtures).

Biochemistry is the study of chemicals found in living things (such as DNA and proteins). It is the branch that will tell us what life is. In conjunction with pharmacology and medicine biochemistry will find ever more powerful means for fighting diseases.

Inorganic chemistry studies substances that do not contain carbon. It is interested in all elements, but particularly in metals, and is often involved in the preparation of new catalysts.

Inorganic chemists have provided the world with countless numbers of useful products, including fertilizers, alloys, ceramics, household cleaning products, building materials, water softening and purification systems, paints and stains, computer chips and other electronic components, and beauty products.

Organic chemistry studies carbon-based substances. Carbon has unique properties that allow it to make complex chemicals, including those of living organisms. An entire field of chemistry is devoted to substances with this element. It is the only element whose atoms are able to combine with each other in apparently endless combinations. Many organic compounds consist of dozens, hundreds, or even thousands of carbon atoms joined to each other in a continuous chain. Other organic compounds consist of carbon chains with other carbon chains branching off them. Still other organic compounds consist of carbon atoms arranged in rings, cages, spheres, or other geometric forms.

Organic chemistry is of special interest because it deals with many of the compounds that we encounter in our everyday lives: natural and synthetic rubber, vitamins, carbohydrates, proteins, fats and oils, cloth, plastics, paper, and most of the compounds that make up all living organisms, from simple one-cell bacteria to the most complex plants and animals.

Physical chemistry is the study of the physical properties of chemicals, which are characteristics that can be measured without changing the composition of the substance. It also deals with rates and energies of chemical reactions. Physical chemists study both organic and inorganic compounds and measure such variables as the temperature needed to liquefy a solid, the energy of the light absorbed by a substance, and the heat required to accomplish a chemical transformation. A computer is used to calculate the properties of a material and compare

This is the structure of table salt, or sodium chloride

these assumptions to laboratory measurements. Physical chemistry is responsible for the theories and understanding of the physical phenomena utilized in organic and inorganic chemistry. The characteristic feature modern chemistry, its difference from the early periods of its development is floaty has now numerous

independent trends, or rather, independent branches of science: electrochemistry, photochemistry, radiochemistry, low-temperature and high-pressure chemistry, high-temperature and low-pressure chemistry, and so on.

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It is common knowledge that a scientist working in one of these branches finds difficulty in understanding his colleague who is a specialist in another branch.

Chemical "dialects" became independent chemical "languages". And this is only part of the trouble. Modern chemistry is closely connected with other sciences: biology, geology, mechanics and cosmogony. These "alliances" formed a whole plaid of hybrid sciences: biochemistry, geochemistry, Cosmo chemistry, physiochemical mechanics, and many others.

Take biochemistry. It is the branch that will tell us what life is. In conjunction with pharmacology and medicine biochemistry will find ever more powerful means for fighting diseases or Cosmo chemistry, the chemistry of the distant stars and planets. In questions concerning the evolution of the universe its say will be decisive.

And here something quite unexpected came to light. It is these hybrid branches that almost daily bear the most remarkable fruit.

The modern subject of chemistry did not appear, however, until the eighteenth century. At that point, scholars began to recognize that research on the nature of matter had to be conducted according to certain specific rules. Among these rules was one stating that ideas in chemistry had to be subjected to experimental tests. Some of the founders of modern chemistry include English natural philosopher Robert Boyle (1627 – 1691), who set down certain rules on chemical experimentation; Swedish chemist Jцns Jakob Berzelius (1779 – 1848), who devised chemical symbols, determined atomic weights, and discovered several new elements; English chemist John Dalton (1766 – 1844), who proposed the first modern atomic theory; and French chemist Antoine-Laurent Lavoisier (1743 – 1794), who first explained correctly the process of combustion (or burning), established modern terminology for chemicals, and is generally regarded as the father of modern chemistry.

Task 6. Answer the following questions.

1. How can chemistry be classified?

2. What does analytical chemistry deal with?

3. What is the subject of biochemistry?

4. Why is organic chemistry devoted to one element only? Why it is so important?

5. What does physical chemistry deal with?

6. What are bio- and cosmo- chemistry? What do they deal with?

7. When did modern chemistry appear? What was it connected with?

8. Who are the fathers of modern chemistry? What is their contribution to chemistry?

9. What is spectroscopy?

Task 7. Match the words and their definitions:

1. Chemistry 2. Homogeneous material 3. Heterogeneous material 4. Compound 5. Substance 6. Chemical reactions 7. Alloy 8. Volumetric analysis	a) is a substance that can be decomposed into two or more substances.
	b) is a metallic material containing two or more elements.
	c) is a homogeneous species of matter with definite chemical composition.
	d) involves the reaction between two liquids in order to determine the composition of one or both of the liquids.
	e) are the processes that convert substances into other substances.
	f) is material consisting of parts with different properties.
	j) is the study of substances, their structure, their properties, and their reactions.
	h) is material with the same properties throughout.

Task 8. Translate from Russian to English

1. Химию можно разделить на два основных направления: описательная химия и теоретическая.

2. Можно разделить химию на несколько направлений: аналитическая, физическая, органическая / неорганическая, биохимия и др.

3. Современная химия характеризуется наличием большого количества независимых направлений.

4. Основоположники современной химии – Бойль, Берцелиус, Дальтон и Жакоб.

5. Известно, что ученые, работающие в разных отраслях химии, с трудом понимают друг друга.

Task 9. Speak about your branch of chemistry and its sphere of interests.