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A study of the periodic table reveals that the position of an element in the table may give an indication of its properties. One of the most striking examples is that all- or nearly all of the elements in the first ten columns have positive magnetic susceptibilities that are they are paramagnetic. On the other hand, all elements in columns to the right of the tenth, with the exception of oxygen, have negative magnetic susceptibilities, or are diamagnetic. Furthermore, the metals that are ferry magnetic, that is are magnetic in the sense that iron is, all lie in the same horizontal line. There are three of them: iron, nickel, and cobalt: elements 26, 27, and 28, respectively. Another interesting fact is that metals in the same column of the periodic table often have similar chemical and physical properties. For example, the three metals of highest electrical conductivity, copper, silver, and gold, all lie in column 11. The three metals in column 4 have the property of absorbing astonishing amounts of oxygen and nitrogen at relatively low temperatures. Even a moderate amount of absorbed gas makes them very brittle although their external appearance may give no indication of their changed condition. This brittleness caused considerable trouble when production was undertaken and required special procedures for melting and hot fabrication. The precious metals, not including silver and gold, lie in a group that includes elements 44, 45, 46, 76, 77, and 78. No mention has yet been made of the two rows in the lower part. These two series of elements usually are called the “rare earths”. The upper one is called the lanthanide series because it fits in the periodic table immediately alter lanthanum. Frequently lanthanum is included in this group because of some chemical similarity and as a convenience in description. These elements have such close chemical similarities that separation of some of them has been difficult. Most of the actinide series, lower strip, show radioactivity. The lower row has been named the actinide series because it follows immediately after actinium.
2.Find in the text English equivalents to the following words and word combinations:
âèçíà÷åííÿ, ìàãí³òíà ñïðèéíÿòëèâ³ñòü, ä³àìàãí³òíèé, ïîãëèíóòèé ãàç, ñïîæèâàííÿ, âåëèêà ê³ëüê³ñòü, êðèõêèé, ïëàâëåííÿ, âèðîáíèöòâî, ð³äêîçåìåëüí³ åëåìåíòè, ëàíòàíîâ³ ãðóïè, âèäîçì³íþâàòè, àêòèí³é.
3.Make up the word combinations from the following words. Translate them into Ukrainian.
Periodic, susceptibilities, external, lower, temperatures, line, striking, conductivity, magnetic, similarity, properties, electrical, table, low, gas, appearance, considerable, horizontal trouble, precious, absorbed, row.
4.Make up word combinations from the following words.
5.Change the following sentences to Subjunctive Conditionals. Translate the sentences into Ukrainian.
Model: If this table indicates the properties of elements, you shall reach success in your research. – If this table indicated the properties of elements, you should reach success in your research
1. If all elements in the first ten columns have magnetic susceptibilities, they will be paramagnetic. 2. All elements will be diamagnetic if they have negative magnetic susceptibilities. 3. If these elements are magnetic, they will lie in the same horizontal line. 4. If metals are situated in the same column of the periodic table, they will have similar chemical and physical properties. 5. If you look at this part of the table, you will see the series of elements called “rare earths”. 6. If elements are included into the same into this group, they will have chemical similarity. 7. If this element follows immediately after actinium, it will belong to the actinide series. 8. If tungsten is called wolfram, we won’t use the previous name. 9. We won’t use the previous name, if beryllium is renamed glucinium.
7. Answer the following questions:
1. What can indicate the position of the element in the table? 2. What elements in the table are called paramagnetic? 3. What elements have the highest electrical conductivity? 4. What elements are called “rare earths”? 5. When was tungsten recommended to be called wolfram?
Final task: Choose one of the following topics and write an essay. Mechanical Properties of Metals. Physical Properties of Metals. Quality and Reliability of the Metals. Metals and Alloys. Aluminium - the Most Abundant Metal. Copper and Its Alloys. Titanium - a Wonder Metal. Engineering Materials. Non-ferrous Metals. Plastics. Metals as Building Materials. Mechanical Treatment of Metals. Fibers – the Oldest Engineering Materials. Factors Affecting Machinability. Hardening and Annealing of Steels. Melting Furnaces. Metallurgical Processes. Metallurgical Furnace Refractories. Materials a Car is Made of. Importance of the Periodic Table of Elements.
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Date: 2015-01-02; view: 989
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