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7. Find in the text and read out English equivalents of these words and word-combinations.
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7. Find in the text and read out English equivalents of these words and word-combinations.
Химический элемент, химическая энергия, химическое соединение, химическая связь, химически соединяться, встречаться в природе, горная порода, земная кора, широко распространенный элемент, часто встречающееся соединение, водород, кислород, углерод, углекислый газ, бесцветный газ, газ без запаха, тяжелее воздуха, встречаться в большом количестве, в соединении с водородом, образование минералов, разрушение минералов.
8. Answer the following questions.
1. What is a chemical element?
2. What is a chemical compound?
3. Do all chemical elements occur naturally only as compounds? What chemical elements occur as native elements?
4. What are the most abundant chemical elements in the earth's crust?
5. What is the content of oxygen in the earth’s crust mass?
6. What physical and chemical properties does oxygen have?
7. What compound does oxygen form in combination with hydrogen?
8. What compound does oxygen form in combination with carbon?
9. What is the second most abundant element in the Earth's crust?
10. Why are calcium, sodium, magnesium, and potassium never found free in nature?
9. Read and translate the words of the same root.
1. To spread – spread – spreading
2. To occur – occurrence – occurring
3. To combine – combination – combining – combined
4. To unite – unit – uniting – united
5. To constitute – constituent – constituting – constitution
6. To form – formation – forming – formed
7. To destruct – destruction
8. To increase – increase - increasing
9. Chemical – chemically – chemistry – chemist
10. Choose the correct word.
1. Oxygen is extremely active (chemical, chemically, chemistry, chemist).
2. Oxygen (unites, unit, uniting, united) directly with a number of other elements (form, to form, formed, formation) oxides.
3. In (combines, combining, combined, combination) with hydrogen oxygen forms water.
4. Oxygen is an important (constitutes, constituting, constituent) of the atmosphere.
5. Silicon is the second most abundant element in the Earth’s crust very rarely (to occur, occurrence, occurring) as the pure free element.
6. Silicon (constitutes, constituting, constituent) almost 28% of the earth’s crust mass.
7. Calcium is a reactive element that is not found free in nature because it readily (formation, forming, formed, forms) compounds with oxygen and water.
11. Match the term with the correct definition.
| 1. Oxygen 2. Hydrogen 3. Water 4. Carbonic acid gas 5. Earth’s crust | a. It is a chemical compound composed of two oxygen atoms a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth’s atmosphere in this state. b. It is the most abundant chemical substance in the universe. At standard temperature and pressure, it is a colourless, odourless, tasteless, non-toxic, highly combustible gas. It is the lightest element on the periodic table. c. It is the solid shell of our planet, which is chemically distinct from the underlying mantle. It is the extremely thin layer of rocks primarily made of granite and basalt. d. It is a chemical compound containing one oxygen and two hydrogen atoms. It is liquid at standard temperature and pressure but it co-exists on the Earth with its solid state (ice) and gaseous state (vapour) e. It is one of the most widely spread chemical elements on the Earth. About one-half of the earth's crust is made up of chemical compounds containing this element, and a fifth of our atmosphere is this gas. |
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12. Fill in the gaps in the text “Oxygen” with the correct word or word-combination: atmosphere, crust's mass, colorless, free element, combination, abundant, tasteless, enormous.
Oxygen
Oxygen is one of the most important and 1)_______ elements on Earth. It isodorless, 2)_______ and 3)_______ and makes up about 21 percent of the atmosphere by volume. Oxygen exists in water as part of water molecule, in the atmosphere as a gas, in the Earth's crust and in an 4)_______ variety of rocks and minerals.
Oxygen is the most abundant element by mass in the Earth's crust as part of oxide compounds such as silicon dioxide, constituting almost half of the 5)_______.
Oxygen is an important part of the 6)_______, and is necessary to sustain most terrestrial life as it is used in respiration. However, it is too chemically reactive to remain a 7)_______ in Earth's atmosphere. In 8)_______ with hydrogen oxygen forms water.
Grammar revision: Active and Passive Voice
| Active Voice | Passive Voice | ||
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Present Indefinite | + | S V (Vs). | S am (is, are) V3. |
| - | S do (does) not V. | S am (is, are) not V3 | |
| ? | Do (does) S V? Wh. do (does) S V? Who Vs? | Am (is, are) S V3? Wh. am (is, are) S V3? Who (What) is V3? | |
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Past Indefinite | + | S V2 | S was (were) V3 |
| - | S did not V. | S was (were) not V3 | |
| ? | Did S V? Wh. did S V? Who V2? | Was (were) S V3? Wh. was (were S) V3? Who (What) was V3? |
13. Put the verbs in brackets into the correct form of Active or Passive Voice.
Facts about Oxygen
Oxygen (discover) by Swedish pharmacist Carl Wilhelm Scheele around 1771. Oxygen, in its most commonly found dioxygen form (O2), is an odorless, tasteless, colorless gas at room temperature.
Oxygen is highly reactive and (form) compounds with most elements. Reaction with oxygen (use) to differentiate metals and nonmetals. Metals (form) basic oxides, while nonmetals (form) acidic oxides.
Oxygen (not burn), but (support) combustion. The term 'combustion' itself (mean) the exothermic reaction of a compound with an oxidant.
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Oxygen (make up) about 89% of the weight of a water molecule (H2O); although there are two hydrogen atoms, they are very light. Water (constitute) 55-60% body weight of an average human. Thus, oxygen (constitute) more than half of our body weight!
Oxygen (support) life on earth, since it (use) in respiration by living organisms. Atmospheric oxygen (create) by plants. Other living beings (depend) on the oxygen released by plants to survive.
Trioxygen, or ozone (O3) is harmful to humans. Fortunately, it rarely (find) on the surface of the earth. It (form) the 'ozone layer' in our atmosphere, which (block) most of the ultraviolet radiation from the sun.
(from: http: //www. buzzle. com/articles/facts-about-oxygen. html)
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