2_kurs_english

MODULE 4

CHEMISTRY AND ITS VALUE

FOR PHARMACY

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PREPARING TO READ…

as you read, notice how:

-the chemical elements are listed in the periodic table; and the main value of the periodic table;

-water takes many different forms on Earth and why humans require water;

-the body uses carbohydrates and what the body feels when this process goes fast or slow;

-and why proteins and amino acids are considered the alphabet of life.

UNIT 1

PERIODIC TABLE

Task 1 Read the text and get ready to discuss it. Use a dictionary, if necessary.

TEXT.

HISTORY OF PERIODIC TABLE

In Ancient Greece, the influential Greek philosopher Aristotle proposed that there were four main elements: air, fire, earth and water. All of these elements could be reacted to create another one; e.g., earth and fire combined to form lava. However, this theory was dismissed when the real chemical elements started being discovered. Scientists needed an easily accessible, well organized database with which information about the elements could be recorded and accessed. This was to be known as the periodic table.

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The periodic table of the chemical elements is a tabular method of displaying the chemical elements. Although earlier precursors exist, its invention is generally credited to Russian chemist Dmitri Mendeleev in 1869. Mendeleev intended the table to illustrate recurring ("periodic") trends in the properties of the elements. The layout of the table has been refined and extended over time, as new elements have been discovered, and new theoretical models have been developed to explain chemical behavior.

The periodic table is now ubiquitous within the academic discipline of chemistry, providing an extremely useful framework to classify, systematize and compare all the many different forms of chemical behavior. The table has also found wide application in physics, biology, engineering, and industry. The current standard table contains 117 confirmed elements as of October 16, 2006 (while element 118 has been synthesized, element 117 has not).

Arrangement

The layout of the periodic table demonstrates recurring ("periodic") chemical properties. Elements are listed in order of increasing atomic number (i.e. the number of protons in the atomic nucleus). Rows are arranged so that elements with similar properties fall into the same vertical columns ("groups"). According to quantum mechanical theories of electron configuration within atoms, each horizontal row ("period") in the table corresponded to the filling of a quantum shell of electrons. There are progressively longer periods further down the table, grouping the elements into s-, p-, d- and f-blocks to reflect their electron configuration.

In printed tables, each element is usually listed with its element symbol and atomic number; many versions of the table also list the element's atomic mass and other information, such as its abbreviated electron configuration, electronegativity and most common valence numbers.

As of 2006, the table contains 117 chemical elements whose discoveries have been confirmed. Ninety-two are found naturally on Earth, and the rest are synthetic elements that have been produced artificially in particle accelerators. Elements 43 (technetium) and 61 (promethium), although of lower atomic number than the naturally occurring element 92, uranium, are synthetic; elements 93 (neptunium) and 94 (plutonium) are listed with the synthetic elements, but have been found in trace amounts on earth.

The main value of the periodic table is the ability to predict the chemical properties of an element based on its location on the table. It should be noted that the properties vary differently when moving vertically along the columns of the table.

UNDERSTANDING DETAILS AND DISCUSSION …

Task 2 Pick up new words from the text. Give their definitions and learn to use them.

Task 3 Use the unknown words in the sentences of your own to show you understand them.

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SKIMMING FOR INFORMATION AND DISCUSSION …

Task 4 Underline the key sentences expressing the main idea in each paragraph.

Task 5 Choose one idea as your topic sentence to discuss with your work partner.

Task 6 Discuss all the passages of the text with your classmates.

Task 7 Make up questions based on the text. Be ready to ask and respond the questions with your partner.

GOING BEYOND THE TEXT...

DISCUSSION …

Task 8 Evaluate the advantages of the periodic table for pharmacy. Pairwork.

ASSIGNMENT …

Task 9 Write a project using the active vocabulary of the text. Present it to your class. Imagine you have discovered a new element … How will you name it? … Describe the element symbol and atomic number, chemical properties, atomic mass, abbreviated electron configuration and other information of the supposed element.

UNIT 2

W A T E R

Task 1 Read the text and get ready to discuss it. Use a dictionary, if necessary.

TEXT A.

WATER

Alternative names: AQUA, DIHYDROGEN MONOXIDE, HYDROGEN

HYDROXIDE

Molecular formula: H2O

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Water is a common chemical substance that is essential to all known forms of life. In typical usage water refers only to its liquid form or state, but the substance also has the solid state, ice, and gaseous state, water vapor.

Water covers 71% the Earth's surface; the oceans contain 97.2% of Earth's water. Saltwater oceans hold 97% of surface water, glaciers and polar ice caps 2.4%; and other land surface water such as rivers and lakes 0.025%.

Water in these forms moves perpetually through the water cycle of evaporation and transpiration, precipitation, and run - off usually reaching the sea. Winds carry water vapor over land at the same rate as run - off into the sea, about

36 Tt1 per year. Over land, evaporation and transpiration contribute another 71 Tt per year to the precipitation of 107 Tt per year over land. Some water is trapped for periods in ice caps, glaciers, aquifers, or lakes for varying periods, sometimes providing fresh water for life on land.

Clean, fresh water is essential to human and other land-based life.

Many very important chemical substances, such as salts, sugars, acids, alkalis, some gases (especially oxygen) and many organic dissolve in water.

Water is a very strong solvent, referred to as the universal solvent, dissolving many types of substances. Substances that will mix well and dissolve in water (e.g. salts) are known as "hydrophilic" (water-loving) substances, while those that do not mix well with water (e.g. fats and oils), are known as "hydrophobic" (water-fearing) substances. The ability of a substance to dissolve in water is determined by whether or not the substance can match the strong attractive forces that water molecules generate between other water molecules. If a substance has properties that do not allow it to overcome these strong intermolecular forces, the molecules are "pushed out" from amongst the water and do not dissolve.

Water takes many different forms on Earth: water vapor and clouds in the sky; seawater and rarely icebergs in the ocean; glaciers and rivers in the mountains; and aquifers in the ground.

Pure water has a low electrical conductivity, but this increases significantly upon solvation of a small amount of ionic material water such as hydrogen chloride. Thus the risks of electrocution are much greater in water with the usual impurities not found in pure water. Any electrical properties observable in water are from the ions of mineral salts and carbon dioxide dissolved in it.

Water can dissolve many different substances imparting upon it different tastes and odors. In fact, humans and other animals have developed senses to be able to evaluate the potability of water: animals generally dislike the taste of salty sea water. The taste advertised in spring water or mineral water derives from the minerals dissolved, while pure H2O is tasteless. As such, purity in spring and

mineral water refers to purity from toxins, pollutants, and microbes.

Humans require water that does not contain too many impurities. Common impurities include metal salts and/or harmful bacteria, such as Vibrio. Some solutes are acceptable and even desirable for taste enhancement and to provide needed electrolytes.

1 Tt – terratonnes

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UNDERSTANDING DETAILS AND DISCUSSION …

Task 2 Pick up the underlined words from the text. Use a dictionary to find their definitions and learn to use them.

Task 3 Use the underlined words in the sentences of your own to show you comprehend them.

SKIMMING FOR INFORMATION AND DISCUSSION …

Task 4 Find some more words relating to water to add to those underlined. Compare them with your partner.

Task 5 Underline the topic sentences expressing the main idea in each paragraph.

Task 6 Choose one idea as your topic sentence to discuss with your work partner.

Task 7 Discuss all the passages of the text with your classmates.

Task 8 Make up questions based on the text. Be ready to ask and respond questions with a partner.

GOING BEYOND THE TEXT …

Task 9 Develop a 10-12 line dialogue using the context of the text.

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MORE ABOUT WATER

Task 1 Scan the text quickly to find some more information about water. Are you able to ask and respond questions?

A. What do we know about water?

We know that water molecules are made of two atoms of hydrogen and one atom of oxygen. Water can take the form of a solid, a liquid, or a gas. Water is used to dissolve many substances; for instance, when we put sugar in our tea, we're dissolving sugar in water. Water doesn't have a high degree of viscosity, so it pours easily. Water is the principal component of our bodies, making up approximately 70 percent of our weight!

B. How pure is the water we use?

Because of its properties, water is used abundantly. The degree of purity which is required of water depends on its use. Water as pure as possible is used for drinking, as well as in food, drug, and chemical industries. The water used in farming doesn't have to be as pure. However, it should not contain excessive amounts of minerals, especially salts, since they may remain in the soil and harm fertile land. The water used in industry as a coolant doesn't have to be completely free of all dissolvedmatter.

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C. Where does rain come from?

The water found in the atmosphere has vaporized from lakes, rivers, seas, oceans, and other sources. The atmosphere can hold a certain amount of moisture at a given temperature. In fact, the warmer the air, the more water it holds. When the amount of moisture exceeds the given amount, we say that the air is saturated. If the air becomes cold after reaching its saturation point, the vapor will condense into tiny drops. Gravity, the natural force by which the earth pulls objects toward its center, pulls the drops down in one of the forms of precipitation - rain, sleet, snow, hail, etc.

D. Where does ordinary drinking water come from?

Most ordinary water comes from the ground. Ground water comes from rain, snow, and other forms of precipitation. For a long time there was no scientific explanation about the origin of ground water. Prior to the 17th century, it was believed that rainfall alone was not enough to supply rivers, lakes, and underground reservoirs. Then, two French scientists looking into the problem found that rainfall was sufficient. Water that evaporates from lakes, rivers, etc., comes down as rain to recharge them. After the scientists' findings, the principle of the natural cycle of water was better understood.

The amount of water that penetrates the ground depends on various factors such as the type of land, the slope* of the land, the amount and kind of precipitation, etc. With an

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excess in rainfall, the rain saturates the ground rapidly. Water penetrates the layers of the earth until it eventually reaches a point where the earth is so compressed that it doesn't permit water to get through. Water accumulates there forming a natural reservoir. Wells are dug to get to the water which is then tested for its purity. If there are impurities, water may have to be processed before we can drink it.

Task 2 Scan each paragraph again and be ready to answer the following questions:

-What is a molecule formula of water?

-What three forms can water take?

-What happens to sugar when you put it in tea?

-Why can you pour water easily?

-Is water an important component of our body weight?

-How pure should drinking water be?

- What minerals should be avoided in water used for farming? Why?

-How pure should water used as a coolant be?

-Where does the water found in the atmosphere come from?

-Can warmer air hold more water?

-What do we mean by "the air is saturated"?

-What happens when the air becomes cold after reaching its saturation point? What pulls the tiny drops down?

-What is precipitation?

-Where does normal water come from?

-Was there an explanation based on science as to the origin of water in the ground?

-Who investigated the origin of ground water?

-What did people believe before the two Frenchmen investigated?

-What was better understood as a result of their findings? What saturates the ground rapidly?

-Where does this water go eventually?

GOING BEYOND THE TEXT... DISCUSSION …

Task 3 Develop and comment on the following ideas:

-how pure the water we use is;

-where rain comes from;

-where ordinary drinking water comes from.

Task 4 Construct with a partner an original 10-12 line dialogue about the degree of water purity we drink.

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UNIT 3

SOLUTIONS

Task 1 Skim through the text to figure out the main idea.

TEXT .

SOLUTIONS

In chemistry, a solution is a homogenous mixture composed of two or more substances. In such a mixture, a SOLUTE is dissolved in another substance, known as a SOLVENT. A common example is a solid, such as salt or sugar, dissolved in water, a liquid. Gases may dissolve in liquids, for example, carbon dioxide or oxygen in water. Liquids may dissolve in other liquids and gases always mix with other gases.

Examples of solid solutions are alloys, certain minerals and polymers containing plasticizers. The ability of one compound to dissolve in another compound is called solubility. The physical properties of compounds such as melting point and boiling point change when other compounds are added. Together they are called colligative properties. There are several ways to quantify the amount of one compound dissolved in the other compounds collectively called concentration. Examples include molarity, molality, and parts per million (ppm).

Solutions should be distinguished from non-homogeneous mixtures such as colloids and suspensions.

Many types of solutions, as solids, liquids and gases can be both solvent and solute, in any combination:

When a substance, called a solute, is dissolved in another substance, called the solvent, a solution is formed. A solution is a uniform distribution of solute in solvent. For example, vinegar is a solution of acetic acid, the solute, in water, the solvent. The amount of solute in a solvent is important and can be expressed in several different ways.

DETERMINE MEANING …

Task 2 Try to work out the meaning of the underlined words from the context. If necessary, use a dictionary to check the meaning.

Task 3 Give examples of solid solutions.

Task 4 Find the respective dictionary definition of ‘solution’ and ‘solvent’.

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Task 5 Study carefully the paragraphs concerning solutions. See what types of solutions are considered and take some notes.

DISCUSSION …

Task 6 What does concentration mean? How should solutions be distinguished from mixtures? Pairwork.

GOING BEYOND THE TEXT...

Task 7 Prepare a short report about solutions and present it for your classmates.

UNIT 4

PROTEINS AND AMINO ACIDS

Task 1 Scan the text for the unfamiliar words and terms so you’ll be able to comprehend the context and discuss it.

TEXT A.

PROTEINS AND AMINO ACIDS

PROTEINS are highly complex compounds elaborated by living cells, and containing the elements of carbon, hydrogen, oxygen, nitrogen and sulphur. These large molecules consisting of up to thousands of AMINO-ACIDS linked together by peptide bonds to form polypeptides which, in turn, are linked to form proteins.

Food supplies the building materials to permit continuous cellular renewal and growth. Protein forms a major part of our structure. Most of our body protein is recycled and we do well by ingesting very little protein. About 3% of the total body protein is recycled every day (approximately 200 grams). In a healthy adult, net protein loss in a day may be as low as 2 grams.

Dietary requirements for protein increase with activity, growth, and protein losses, especially following injury or during illness. The average American diet supplies 11-14% of total calories as protein, or 25-300 gms/day. Protein digestion and absorption are generally efficient. A minimum average protein intake is approximately 25 grams.

Since all amino acids contain a nitrogen atom (N), protein balance is synonymous with nitrogen balance. When nitrogen intake exceeds nitrogen loss, there is net protein synthesis. Anabolism, or tissue construction, prevails. When nitrogen losses exceed intake, protein tissue is being broken down and catabolism prevails. Loss of protein-tissues occurs with malnutrition, following surgery, injury, and chronic illness.

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