Санкт-петербургского государственного университета высшее профессиональное образование т. А. Степанова, И. Ю. Ступина
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| Scction II
Упр. 1. Назовите значения следующих интернациональных слов: composition, identical, ozone, sort, dimethyl, amine, gas, clcctricity, covalcnt, ocean, ordinary, illuminate, optical, microscopc, vision, especially Упр. 2. Определите значения выделенных слов по контексту. 1. The boiling point of water is 100°C. 2. The original temperature o f the solid was 23°C, then it was heated to 100°C. 3. When a thing is not visible by man’s eye optical instruments should be used. 4. It is not possible to see atoms with the most powerful microscopc. 5. Some substanccs fa il to react at room temperature. 6. It is claimed that an electron microscope is a very useful instrument for molecular investigations. Слова к тексту: size — размер; per — на, в; melt — плавиться; tiny — крошечный; meaningful — имеющий смысл; dye — окрашивать; throw — бросать; at random — наугад; exceedingly — чрезвычайно; directly — прямо, непос редственно; reveal — обнаружить; resolve— физ. разрешать Text 16 В Прочтите текст про себя (контрольное время чтения— 4,5 минуты). M olecular C om position an d Size Molecules are chemical units composed of one or more atoms. The simplest molecules contain one atom cach; for example, helium atoms (one atom per molcculc) arc identical with helium molcculcs. Oxygen tonoleculcs ( 0 2) are composed o f two atoms, and ozone (0 3) o f three. Molecules may contain several different sorts o f atoms. Water (H20 ) contains two different kinds, hydrogen and oxygen, and dimethyl amine ((CHj^NH) has three kinds. Molecules of many common gases (hydrogen Нг, oxygen Ог, nitrogen N 2 , and chlorinc Cl2) consist o f two atoms cach. Not all molecules are molecular in structure. Some are atomic and many are ionic. Molecular substances are characterized by low boiling points and poor conductivity of clcctricity when dissolved or melted. Gases are generally molecular, and so are many liquids, and some solids. All compounds of hydrogen and поп-metallic oxides arc molecular. These compounds arc considered to be bonded by a force callcd a covalcnt bond (or bonds) which consists o f one or more shared electron pairs. The size of molecules, especially of the smaller ones, is so tiny that to make a meaningful comparison is rather difficult. Let us assume that the water molcculcs in a cup o f water arc dyed so that they can be identified. If this cup had been thrown into the ocean 2,000 years ago, these molecules would have become distributed evenly in all bodies of water on the earth. US A cup of water taken at random from your nearest supply, would give you at least one hundred of the original dyed molcculcs. The exceedingly large number of molcculcs of water in a cup is, of coursc, directly related to the fact that each molecule is exceedingly small. Molcculcs arc too small to be visible in ordinary light. The most powerful and best illuminated optical microscope has failed to reveal molcculcs by direct vision, although it is claimcd that they have been resolved in the electron microscope. Упр. 3. Передайте основное содержание текста в нескольких пред ложениях. Упр. 4. Составьте план текста. Упр. 5. Прочтите предложения и скажите, соответствуют ли они содержанию текста. Если нет, исправьте их. 1. Molcculcs usually contain several different kinds of atoms. 2. The water moleculc is composed of two different sorts of atoms. 3. Molcculcs o f all gases consist of two atoms. 4. Molcculcs may be molecular, atomic or ionic in structure. 5. There is no difficulty in comparing molcculcs by their size. 6. Molcculcs are too small and cannot be seen by ordinary means. 7. The electron microscopc is the most powerful instrument that is used for molecular investigations. Ex. 6. Найдите в тексте и переведите на русский язык предложения, где идет речь о молекулах, состоящих из разнородных атомов, а также предложения, в которых дается характеристика таких молекул. жүктеу/скачать 5,96 Mb. Достарыңызбен бөлісу:
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