3 Part One. The Predicate

The Galogens
Galogens may have interested chemists since early times, for they possess unique properties. They must have interested scientists as all of them, F₂, Cl₂, Br₂ and I₂, consist of diatomic molecules. We are going to touch upon some of their properties in what follows.Chlorine (from Greek “chloros”, greenish-yellow), the most common of the galogens is a greenish-yellow gas with a sharp irritating odour. It was first made by ihc Swedish chemist K. W. Scheele in 1774, by the action of manganese dioxide on hydrochloric acid. It is now manufactured on a large scale by the electrolysis of a strong solution of sodium chloridc.

The element bromine (from Greek “bromos”, stench) occurs in the form of compounds in small quantities in seawater and in natural salt deposits. It is an easily volatile, dark reddish-brown liquid with a strong disagreeable odour and an irritating cficct on the eyes and throat. It may producc painful sores when spilled on the skin. The free clement can be made by treating a bromide with an oxidizing agent, such as chlorine.

The clement iodine (from Greek “iodes”, violet) occurs as iodide ion, I₂, in very small quantities in seawater, and, as sodium iodate, NaIO₃, in deposits of Chile saltpeter. It is made commercially from sodium iodate obtained from saltpeter, from kelp, which conccntratcs it from seawater, and from oil-well brines.

The free element is an almost black crystalline solid with a slightly metallic lustre. On gentle warming it gives a beautiful blue-violet vapour. Its solutions in chloroform, carbon tctrachloridc, and carbon disulphidc are also bluc-violct in colour, indicating that the molecules I₂ in these solutions closely resemble the gas molecules. The solutions of iodine in water containing potassium iodide and in alcohol (tincturc o f iodine) are brown; this changc in colour suggests that the iodine molecules have undergone chemical reaction in these solutions. The brown compound KI₃, potassium-triiodidc, is present in the first solution, and a compound with alcohol in the second.

Words and Word-Combinations to Be Memorized

alcohol, bromine, chloride, chlorine, common, diatomic, follow, be going to, galogen, hydrochloric acid, iodide, iodine, lustre, manganese, oil, possess, potassium, producc, quantity, on a large scale, sharp, sodium, suggest, tincture, touch, treat, unique, volatile

Ex. 6. Give the Uzbek equivalents for the following:

since early times, interest smb., possess unique properties, diatomic molecules, be going to, greenish-yellow, a sharp irritating odour, hydro­chloric acid, be manufactured on a large scale, a strong solution, occur in the form of compounds, a small quantity, natural salt deposits, be volatile, treat smth. with an oxidizing agent, a black crystalline solid, a slightly metallic lustre, on warming, resemble gas molecules, undergo chemical reaction, be present in solution

Ex. 7. Give the English equivalents for the following:

Katta hajmdagi diatomik molekulalar, xlorid kislota, halol elektroliz, dengiz suvidagi natriy xlorid eritmasi, uchuvchan, noyob xususiyatlarga ega, oksidlovchi, juda oz miqdorda bo'ladi, dengiz suvidan olinadi va erkin holatda bo'ladi. , kristalli qattiq, metall porlashi, spirtdagi yod eritmasi, reaktsiyaga kirishishi, eritmada bo'lishi, taklif qilishi (taklif qilishi)

Ex. 8. Fill in the blanks with prepositions where necessary.

in, of with, on, by

1. All the galogens consist ... diatomic molecules. 2. The most common ... the galogens is chlorine. 3. Chlorine was first made ... the action... manganese dioxide... hydrochloric acid. 4. It was obtained by K.W. Scheele... 1774. 5. Now chlorine is manufactured... a large scale ... the electrolysis ... a strong solution ... sodium chloride. 6. Bromine occurs... the form o f compounds... small quantities. 7. Bromine has an irritating effect ... the eyes and throat. 8. Iodine is an almost black crystalline solid ... a slightly metallic lustre. 9. The I2 molecules ... the solutions ... chloroform, carbon tetrachloridc and carbon disulphide closcly resemble the gas molecules. 10. The solution iodine ... alcohol is brown... colour.

Ex. 9. a) Check up if you remember the following:

b) Translate the sentences into Uzbek.
1. The first solution of sodium chloride is much stronger than the second solution. 2. Fluorine is a great deal more activc than the other galogens. 3. Iodine is much heavier than bromine. 4. A surfacc coating protects some compounds from still further oxidation. 5. Potassium is much lighter than rubidium, and sodium is still lighter. 6. Amorphous boron is much more reactive chemically than is the harder, more expensive crystalline variety. 7. The nuclcus o f an atom is much smaller than is the atom itself. 8. Antimony is much more metallic in appcarancc and in properties than either phosphorus or arsenic. 9. Studies o f crystal chem­istry have attracted much greater interest during the last decade than ever before. 10. Carbon tetrachloride is a liquid much more dense than water. 11. Bromine is far less abundant than chlorine or fluorine. 12. Steel is far less brittle than cast iron.
Ex. 10.Translnte the sentences into Uzbek, paying attention to modal verbs.

1. The text that you must have read describes the properties of galogens.2. This student can’t have started the reaction before learning the properties of the substances. 3. The author may have supposed that this description would help to understand his idea better. 4. The teacher may have spoken about such reactions, I don’t remember. 5. Mendeleyev could have presented his periodic system himself, but he was ill. 6. You ought to have been more attentive working in the laboratory. 7. The scientists of our faculty may have discovered some new properties of electrodes, now they are writing an article on this problem. 8. Everyone must have noticed a blue-violet vapour when iodine was being warmed. 9. The reaction may not proceed to completion without heating. 10. The laboratory assistant can’t have done all the work alone. 11. Our friends haven’t come yet, they must be still working in their laboratory. 12. You should have paid more attention to a theoretical course before starting your practice. 13. The reaction must have occurred, the colour ofthe reagents has changed. 14. Chemistry couldn't have reached the present level of development without the atomic theory. IS. The discovery of the periodic law must have been the greatest discovery in the nineteenth-century chemistry. 16. The researehers would have tested their results by experiment, but they had no all the necessary apparatus. 17. Newton may have thought that light was a stream of particles. 18. Suggestions were made as to what may have occurred during the reaction.

Ex. 11. Translate the sentences into English.

1. Galogenlar VII guruh elementlari. 2. Barcha galogenlar diatomik molekulalardan iborat. 3. Eng keng tarqalgan galogen, xlor, yashil-sariq rangli gazdir. 4. Xlorni birinchi bo'lib 1774 yilda shved kimyogari Sheele olgan.

5. Hozirda xlor natriy xlorid eritmasining elektrolizi yordamida katta miqyosda ishlab chiqariladi, 6. Brom dengiz tuzida va tabiiy tuz konlarida oz miqdordagi birikmalar shaklida mavjud. 7. Yod dengiz suvida juda kam miqdorda ham bo'lishi mumkin.
Ex. 12. Make up questions to the italicized parts of the sentences.

1. Galogens may have interested chemists since early times (3).2. Iodineis an almost black crystalline solidwith a slightly metalliclustre (3). 3. The solutionsof iodine in water containing potassium iodide and inalcoholare brown(3).

Ex. 13. Answer the following questions:

1. What elements are called galogens? 2. Why may the galogens have interested chemists? 3. What is the most common of the galogens?4. When was chlorine obtained? 5. In what way is chlorine obtained now? 6. What kind of element is bromine? 7. Where does bromine occur and in what form? 8. In what way is iodine made commercially? 9. What kind of element is iodine?