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Everything you can touch or see or smell contains one or more chemicals. We live in a world of chemicals – many occur naturally, some are synthetic. Over 25 million chemicals are now known which is an increase of 5 million in just one year. From the rich colours of beautiful flowers to the brilliant synthetic pigments in the latest fashions to the eye catching colours of photographs, printer inks and television screens, chemistry is on display. Chemicals are present in food, medicine, vitamins, paint, glue, cleaning products, building materials, automobiles, electronic and sporting equipment and everything else you can buy. Chemistry is the study of matter and the changes it undergoes. Chemistry is often called the central science, because a basic knowledge of chemistry is essential for students of biology, physics, geology, ecology and many other subjects. Indeed, it is central to our way of life; without it, we would be living shorter lives in what we would consider primitive conditions, without automobiles, electricity, computers, CDs, and many other everyday conveniences. Although chemistry is an ancient science, its modern foundation was laid in the nineteenth century, when intellectual and technological advances enabled scientists to break down substances into ever smaller components and consequently to explain many of their physical and chemical characteristics. The rapid development of increasingly sophisticated technology throughout the twentieth century has given us even greater means to study things that cannot be seen with the naked eye. Using computers and special microscopes, for example, chemists can analyze the structure of atoms and molecules-the fundamental units on which the study of chemistry is based – and design new substances with specific properties, such as drugs and environmentally friendly consumer products. As we enter the twenty-first century, it is fitting to ask what part the central science will have in this century. Almost certainly, chemistry will continue to play a pivotal role in all areas of science and technology. Before plunging into the study of matter and its transformation, let us consider some of the frontiers that chemists are currently exploring. Some chemicals can save lives; some can be lethal. Many chemicals are potentially both harmful and helpful. It is how we handle and use them, that makes the difference. An understanding of fundamentals of chemistry is essential to the proper handling and use of chemicals and to many careers. Furthermore, in our rapidly changing world, there is a new sense of urgency for all of us – regardless of career choices- to understand fundamentals of chemistry. Chemicals are everywhere; without chemicals, life itself would not be possible. The truth is that every one of us- trained or not – is a chemist because we work with chemicals. We can be better chemists when we understand more chemistry. All texts from: Fundamentals of Chemistry By Burns, Ralph Chemistry In the Community: A Project of the American Chemical Society by Freeman, W. H. and company Chemistry by Chang, Raymond Solar energy promises to be a viable source of energy for the future. The Sun’s energy is produced by continuous nuclear-fusion reactions. Every year Earth’s surface receives about 10 times as much as energy from sunlight as is contained in all of the known reserves of coal, oil, natural gas and uranium combined. But much of this energy is “wasted” because it is reflected back into space. For the past 30 years, intense research efforts have shown that solar energy can be harnessed effectively two ways. One is the conversion of sunlight directly to electricity using devices called photovoltaic cells. The other is to use sunlight to obtain hydrogen from water. The hydrogen can be fed into a fuel cell to generate electricity. Although our understanding of the scientific process of converting solar energy to electricity is advanced, the technology has not yet improved to the point where we can produce electricity on a large scale at an economically acceptable cost. By 2050, however, it has been predicted that solar energy will supply over 50 percent of our power needs. As you drive your car, energy is released as gasoline combines explosively with oxygen gas to give carbon dioxide and water vapour. This is an example of a common, but exceedingly important chemical change or chemical reaction. During a complex series of reactions within the cells of your body, glucose and other carbohydrates in food are consumed (metabolized) as they react with oxygen to produce carbon dioxide and water vapour that are exhaled as you breathe. The food we eat is broken down, or metabolized in stages by a group of complex biological molecules called enzymes. Most of the energy released at each stage is captured for function and growth. One interesting aspect of metabolism is that the overall change in energy is the same as it is in combustion, For example, the total enthalpy change for the conversion of glucose to carbon dioxide and water is the same whether we burn the substance in air or digest it in our bodies. Various food have different compositions and hence different energy contents. The energy content of food is generally in calories. Food is made up of many types of chemicals. Some of these provide energy; others can be toxic or cause allergic reactions in certain individuals. Each prescription medicine and over-the-counter drug contain chemicals that undergo specific chemical reactions within the body. Along with beneficial effects are side effects. There is often a trade –off between risk and benefit. For example, aspirin is a chemical that reduces both fever and pain but also thins the blood and may aggravate an ulcer condition. All texts from: Fundamentals of Chemistry By Burns, Ralph Chemistry In the Community: A Project of the American Chemical Society by Freeman, W. H. and company Chemistry by Chang, Raymond Chemical reactions occur when substances undergo fundamental changes in identity; one or more substances are used up while one or more substances are formed. The substances present at the beginning of a reaction, the starting materials are called reactants. The substances produced by the reaction are called products. CLOSER LOOK AT DIFFERENT TYPES OF REACTIONS 1. Combustion Reactions. During combustion, compounds containing carbon, hydrogen, and sometimes oxygen burn in air (consuming oxygen) to produce carbon dioxide and water. 2. Combination (Synthesis) Reactions. When one element reacts or combines with another element to produce a compound, we can say that a new substance is synthesized. Reactions of this type are classified as combination or synthesis reactions. They can be represented in a general way as follows. 3. Decomposition Reactions. A decomposition reaction is one in which a single compound (symbolized as AB) is broken down into two or more simple substances. This type of reaction can be represented as follows. 4. Single-Replacement Reactions. In single-replacement reactions, an element symbolized as A, reacts with compound, BC, to take the place of one of the components of the compound. This type of reaction can be represented by the following general equation. 5. Double-Replacement Reactions. In double-replacement reactions, two compounds, AB and CD, can be thought of as “exchanging partners” to produce two different compounds, AD and CB. The types of bonds that are present in a substance are largely responsible for the physical and chemical properties of the substance. Bonding is also responsible for the attraction one substance has for another. For example, salt dissolves in water much better than in oil because of differences in bonding. Certain substances dissolved in water can conduct an electric current, but others cannot. Ethyl alcohol evaporates more quickly than water. Wax melts at low temperatures, but salt has a high melting point. These properties of substances and many more can be explained in terms of differences in chemical bonding. All texts from: Fundamentals of Chemistry By Burns, Ralph Chemistry In the Community: A Project of the American Chemical Society by Freeman, W. H. and company Chemistry by Chang, Raymond 1. Do laboratory work only when your teacher is present. Unauthorized or unsupervised laboratory experimenting is not allowed. 2. Your concern for safety should begin even before the first laboratory investigation. Before starting any laboratory work, always read and think about the details of your laboratory assignment. 3. Know the location an use of all safety equipment in your laboratory like fire extinguisher, exits, emergency warning system, evacuation routes and etc. 4. Clear your bench top of all unnecessary material such as books and clothing before 5. Check chemistry labels twice to ensure that you have the correct substance and the correct solution concentration. Some chemical formulas and names may differ by only a letter or a number. 6. You may be asked to transfer some chemical substances from a supply bottle or jar to your own container. Do not return any excess material to its original container unless authorized by your teacher, as you may contaminate the supply bottle. 7. Never taste any laboratory materials. Do not bring gum, food or drinks into the laboratory. Do not put fingers, pens or pencils in your mouth while in laboratory. 8. If you are instructed to smell something, do so by fanning some of the vapour toward your nose. Do not place your nose near the opening of the container. 9. Never look directly down into a test tube; view the contents from the side. Never point the open end of a test tube toward yourself or your neighbour. 10. Any laboratory accident, however small, should be reported immediately to your 11. In case of a chemical spill on your skin or clothing, rinse the affected area with plenty of water. If your eyes are affected, rinsing with water must begin immediately and continue for at least 10 to 15 minutes. Professional assistance must be obtained. 12. Minor skin burns should be placed under cold, running water. 13. When discarding or disposing of used materials, carefully follow provided 14. Wash your hands before leaving the laboratory. 15. If you are unclear or confused about proper safety procedures, ask your teacher for All texts from: Fundamentals of Chemistry By Burns, Ralph Chemistry In the Community: A Project of the American Chemical Society by Freeman, W. H. and company Chemistry by Chang, Raymond Additional literature for those who wish to read more: 1. Fundamentals of Chemistry by Ralph A. Burns 2. Chemistry In the Community: A Project of the American Chemical Society by W.H. 3. Chemistry by Raymond Chang 4. Introduction to Physical Chemistry of foods by Christos Ritzoulis, translated by 5. Chemistry and the Environment by Sven E. Harnung, Matthew S. Johnson 6. Chemistry in the Laboratory by James M. Postma, Julian L. Roberts, J. Leland 7. Organic Chemistry by John McMurry 8. Inorganic Chemistry by James E. House 9. Reactions and syntheses in the organic chemistry laboratory by Lutz F. Tietze, Theophil Eicher, Ulf Diederichsen, Andreas Speicher 10. Fundamentals of Chemistry by David E. Goldberg For sure you can find plenty of literature in your own language. This is just short list, which of you can find translations as well. All texts from: Fundamentals of Chemistry By Burns, Ralph Chemistry In the Community: A Project of the American Chemical Society by Freeman, W. H. and company Chemistry by Chang, Raymond

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