М. М. Кутепова The World of Chemistry Мир

Read the following text, entitle it and write an abstract:

In 1896, one year after the discovery of X-rays by Roentgen, a French physicist, Becquerel, discovered that uranium emits rays similar to those of X-rays; these rays were called “Becquerel rays”.
In 1897, two brilliant physicists, Maria Sklodowska-Curie and Pierre Curie, began work on pitchblende residues from Bohemia


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containing uranium oxide, U₃0₈. Soon they discovered an element more radioactive than uranium itself and this was named polonium, in honour of Marie’s native Poland. The Curies then succeeded in separating radioactive barium sulphate from pitchblende. This led them to conclude that pitchblende contains a certain element which renders other elements radioactive. Consequently, they treated the barium sulphate and obtained a new compound, one million times as active as uranium, radium bromide. In 1902, after completing nearly five hundred experiments, Madam Curie obtained about 0.2 gram of radium chloride from a series of fractional crystallizations of pitchblende. This compound is a salt of radium and its activity is over two million times as great as that of uranium. In 1910, four years after her husband had been killed in a street accident, Madam Curie finally succeeded in isolating pure radium from radium chloride. Thus, the science of radioactivity was established, a new science that has changed many concepts regarding the structute of matter, and opened the door to the Atomic Age.

During their research, the Curies also discovered that thorium is nearly as radioactive as uranium. Many new radioactive elements have been discovered since Madam Curie succeeded in isolating pure radium, but uranium and thorium still comprise the parent elements of natural radioactivity.

6. 
   a) You’re given descriptions of ten elements of the Periodic Ihble. Give the names and symbols of the elements. If in the given definitions some important details are lacking, add whatever you consider necessary. Choose the elements from the list below:
   

chlorine, tin, hydrogen, zinc, copper; bromine, carbon, helium, silver, oxygen

1. 
   Chemically it is a reactive metal, combining with oxygen and other nonmetals and reacting with dilute acids to release hydrogen.
   
2. 
   Chemically it is reactive. It combines directly with chlorine and oxygen and displaces hydrogen from dilute acids. It also dissolves in alkalis to form stannates.
   
3. 
   It is a white lustrous soft metallic transition element. It is used in jewellery, tableware, etc., and its compounds are used in photography.
   

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4. 
   A colourless, odourless gaseous element. It is the most abundant in the Earth’s crust (49.2 percent by weight) and is present in the atmosphere (28 percent).
   
5. 
   A colourless, odourless gaseous chemical element. It is the lightest and the most abundant element in the universe. It is used in the Haber process.
   
6. 
   This nonmetallic element is totally inert and has no known compounds. It was discovered in the solar spectrum in 1868.
   
7. 
   It is a red volatile liquid at room temperature. Chemically, it is intermediate in reactivity between chlorine and iodine. The liquid is harmful to human tissues and the vapour irritates the eyes and throat.
   
8. 
   It is manufactured by the electrolysis of brine and also obtained in the Downs process for making sodium. It has many applications, one of which is purification of drinking water.
   
9. 
   The name of this element comes from the island of Cyprus. It is used for making electric cables and wires. Its alloys are used extensively. Water does not attack it, but in moist atmospheres it slowly forms a characteristic green surface layer (patina).
   
10. 
    A nonmetallic element belonging to group IV of the Periodic Table. It has two main allotropic forms (diamond and graphite).