I. Speaking: Chemistry, Matter and Life

After careful study of this unit you should be able to:

• describe the structure of an atom;

• differentiate between atoms and molecules;

• define the atomic number of an atom;

• differentiate between elements and compounds;

• explain why water is so important to the body;

• define mixture, name three types of mixtures;

• define acid, base, and salt;

• give characteristics of organic compounds;

• define enzyme.

Exercise 1. Learn the following words and word combinations, acid ['aesictj кислота atom ['setam] атом

base [beis] основа, луг

carbohydrate [,ka:bau'haidreit] вуглевод

compound ['kampaund] складний; суміш; сполучення, сполука

electron [i'lektran] електрон

element ['elimsnt] елемент

enzyme ['enzaim] фермент

ion [аізп] іон

lipid [lipid] ліпід

mixture ['mikstfa] суміш; мікстура

molecule ['niDlikju:l] молекула

neutron ['njir.tron] нейтрон

organic [3:'gasnik] органічний

pH ['pi: eitT] водневий показник

protein ['preutkn] білок

proton ['prsotDn] протон

solute [sD'lju:t] розчин; розчинена речовина

solution [s3'lu:J(a)n] розчин

solvent ['solvent] розчинник

suspension [sas'penjn] суспензія

matter ['maets] речовина; матерія

absorption [£eb'so:pJ(3)n] абсорбція, всмоктування, вбирання excretion [iks'kri:J(3)n] виділення

Exercise 2. Read the text.

Chemistry, Matter, and Life

Chemistry is the science that deals with the composition of matter. Knowledge of chemistry and chemical changes helps us to understand the normal and abnormal functioning of the body and its parts. The main processes are based on chemical principles. Chemistry is important in microbiology and pharmacology. Atoms, molecules, elements, compounds, and mixtures are fundamental units of matter.

Atoms are the basic units of matter that make up various elements on the Earth. Everything about us, everything we can see and touch, is made of atoms - the food we eat, the atmosphere, я atcr in rivers, seas and oceans.

Each atom has a definite structure. At the center of an atom there is a nucleus with positively charged protons and noncharged neutrons. Outside the nucleus in orbitals there are negatively charged electrons (Fig. 2-1).

Atoms are fundamental units that make up the chemical elements from which all matter is ~ade. The entire universe is made up of about 105 elements. Elements can be identified by their Raines, symbols, or their atomic numbers.

The atomic number is equal to the number of protons that are presenting the nucleus (the ■ -imber of protons is equal to the number of electrons).

Look at the Table:

Common Chemical Elements Found in the Human Body

Name	Symbol	Atomic Number
Hydrogen	H	1
Carbon	c	6
Nitrogen	N	7
Oxygen	О	8
Sodium	Na	11
Phosphorus	P	15
Sulfur	S	16
Chlorine	CI	17
Potassium	K	19
Iron	Fe	26

When, on the basis of electron structure, two or more atoms unite, a molecule is formed. For example, a molecule of water contains 1 atom of oxygen and 2 atoms of hydrogen (Fig. 2-2).

Substances that contain molecules formed by the union of two or more different atoms are called compounds. These combinations may be simple and very complex.

Water is the most necessary compound in the body. No plant or animal, including human, can live very long without water.

It is very important to all physiologic processes in body tissues. Water carries substances to and from the cells and makes possible the essential processes of absorption, exchange, secretion and excretion. Why it is so important:

• it is the universal solvent (it dissolves minerals, nutrients and gases);

• it is a stable liquid (it doesn't freeze until the temperature falls to 0"C and doesn't boil until the temperature rises to 100 C);

• it participates in chemical reactions that occur in the cells.

Not all elements or compounds combine chemically when brought together. The air we breathe consists of gases: nitrogen, oxygen, carbon dioxide, and their proportions in the air may vary. The blood plasma also consists of various components. Such combinations are called mixtures - blends of two or more substances.

Solution is substance (solute) remains evenly distributed in a solvent (e.g. salt in water, glucose in water).

Suspension is a dispersion of fine solid or liquid particles in a fluid, the particles being supported by buoyancy (e.g. red blood cells in plasma, milk of magnesia, india ink). Colloidal suspension forms when the particles do not dissolve but remain suspended (e.g. cytoplasm, blood plasma).

An acid is a chemical substance capable of donating a hydrogen ion (H⁺) to another substance. A common example is HC1 (hydrochloric acid, found in the stomach juices:

HC1 - H' + Ch

A base is a chemical substance usually containing a hydroxide ion (Off) that can accept a hydrogen ion:

NaOH -» Na +OH. A reaction between an acid and a base produces salt:

HC1 + NaOH -» NaCl + H,0. Acids, bases and salts are chemical compounds. In the body there are also organic compounds: carbon, hydrogen, and oxygen containing. The main types of them are carbohydrates, fats and proteins.

Carbohydrates are the simple sugars called monosaccharides [,іштзи'saeks raidz]. Examples of carbohydrates in the body are the glucose that circulates in the blood as a food for the cell and a storage form of glucose called glycogen ['glaikaixhpn].

Fats, or lipids, are also a store of energy in the body. They provide insulation and protection for the body organs. All proteins contain carbon, hydrogen, oxygen and nitrogen, they may also have sulfur and phosphorus. Proteins are composed of building blocks called amino [з'таіпзп] acids. About twenty different amino acids are found in the body. An important group of proteins is enzymes. Enzymes function as catalysts in hundreds of reactions that occur in metabolism. A catalyst is a substance that speeds up the rate of a reaction but is not changed or used up in that reaction. Examples of them are: amylase, lipase, oxidase.

Exercise 3. Title each passage of the text making a plan of it.

Exercise 4. Find English equivalents of the Latin words, give Ukrainian translation.

atomus, i, f compositus, a, um

structura, ae, f mixtura, ae, f

celula, ae, f oxygenium, ae, f

solutio, onis, f hydrogenium, i, n

sulfur, uris, n phosphorus, і, m

simplex, icis saccharum, i, n

Exercise 5. Look at Figure 2-1 and describe the atom of oxygen.

Exercise 6. Translate into English.

1. Протони - це позитивно заряджені частки.

2. Нейтрони - це нейтральні частки ядра.

3. Електрони - це негативно заряджені частки на енергетичних рівнях навколо ядра

4. Сполуки - це поєднання різних атомів.

5. Мікстура - це суміш кількох речовин.

Exercise 7. Answer the following questions.

1. What science is chemistry?

2. What are atoms and what is known of their structure?

3. What chemical elements do you know?

4. Why is water so important to life?

5. What is the difference between a mixture and a compound?

6. You dissolve a teaspoon of sugar in a cup of tea. Which is a solute? A solvent?

7. What are organic compounds and what elements are found in all of them?

8. What type of organic compounds are enzymes?

9. What are proteins? Fats? Carbohydrates?

Exercise 8. Complete the sentences.

Atoms

Molecules

Elements

Compounds

Mixtures

Acid

Base

Salt

Enzyme

blends of 2 or more substances, combinations of different atoms, basic units of matter, combinations of 2 or more atoms, substances that cannot be changed into something else.

a chemical substance capable of donating a hydrogen ion (FT).

a chemical substance resulting from a

reaction between an acid and a base.

a chemical substance containing a hydroxide

ion (OH).

an organic catalyst.