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Chemistry is the science which deals with materials, their properties and the transformations they undergo. So chemistry is the study of the composition and properties of matter, their changes, the conditions under which such changes take place, and the energy changes which accompany them.

Chemistry is concerned with the nature of fire and the structure of water, it deals with colours, catalysis and crystal structure, with physical properties and chemical reactivity.

Chemistry is one of the fundamental sciences. It plays an important part in the development of biochemistry, physics, geology, and many other fields of science. Chemistry's origin goes back to ancient times, with the manufacture of bronze, iron, ceramics, glass.

At the end of the sixteenth century sufficient facts, entirely free of magic which surrounded the work of the alchemists, appeared.

In the 17th century modern chemistry began with the work of Robert Boyle. He was the first one who studied quantitatively the relationship between the volume of a gas and the external pressure upon it. Later A. Lavoisier introduced the concept of the chemical elements.

In the 19th century A. Avogadro introduced the concept of molecules. He stated that equal volumes of gases under the same conditions of temperature and pressure contain the same number of molecules.

F. A. Kekule and A. M. Butlerov introduced the structural theory of organic chemistry.

In 1869 D. I. Mendeleyev discovered regularities in the properties of the elements. D. I. Mendeleyev's discovery was the greatest one in chemistry.

Many great scientists devoted their life to the development of chemistry, among them Bohr whose theory of the hydrogen atom was very important, the Curies who in 1934 announced the preparation of artificially radio-active elements, Marie Curie who discovered radium and the element polonium. Many great Russian chemists made a great contribution to the world science. Among them, the outstanding Russian chemists M. V. Lomonosov, D. I. Mendeleyev, A. M. Butlerov, Academician N. N. Semenov, and many others.

Everyone now understands the importance of chemistry. The future of chemistry is practically unlimited. Rapid development of chemical industry will make it possible tocreate many new goods, machines, plastics, polymers, it will help to understand many new phenomena.

In your study of chemistry you will learn many things about substances, compounds, materials, chemical and physical changes, chemical properties, reactions and many other interesting and important things. It is to be remembered that:

1. Chemistry is the study of substances, their structure, their properties, and their reactions.

2. Matter exists as solids, liquids, or gases.

3. Homogeneous material is material with the same properties throughout.

4. Heterogeneous material is material consisting of parts with different properties.

5. Compound is a substance that can be decomposed into two or more substances.

6. Substance is a homogeneous species of matter with definite chemical composition.

7. Chemical reactions are the processes that convert substances into other substances.

8. Alloy is a metallic material containing two or more elements.



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