На пути в научную библиотеку

not normally radioactive. Five years later Otto Hahn, Fritz Strassmann, and Lise Meitner discovered that the uranium nucleus could be made to fi ssion, or split into the nuclei of lighter elements, by bombarding it with uncharged particles called neutrons.

By the early 1940s nuclear reactions had been used to make radioactive isotopes of all elements; Glenn Seaborg contributed much to this work. In the 1940s and ‘50s Seaborg and his co-workers also made several elements not known to exist in nature. The new elements had atomic numbers greater than 92, the atomic number of uranium. By the early 21st century nuclear scientists were adding new elements to the periodic table with atomic numbers higher than 110.

Rutherford’s discovery in 1911 that the atom has a tiny massive nucleus at its center allowed chemists and physicists such as Gilbert Lewis, Irving Langmuir, and Niels Bohr over the next 20 years to explain chemical bonding and atomic structure in terms of the behavior of electrons orbiting the nucleus. In the late 1920s and early 1930s, Linus Pauling contributed much to knowledge of the nature of the chemical bond and of the relationship between the structure of atoms and molecules and their properties.

(adopted from «nuclear chemistry.» Britannica Student Library. Encyclopædia Britannica. Chicago: Encyclopædia Britannica, 2007.)

Exercise 1. Look through the text and define which of the following keywords are mentioned. Put them in the order they appear in the text.

radioactivity tube phenomenon isotope nitrogen nucleus cup

Exercise 2. What do the key-words from Exercise 1 refer to?

Exercise 3. Are the following statements true or false?

1.In 1896, Dmitrii Mendeleyev discovered the phenomenon of radioactivity.

2.Scientists were shown that atoms were not permanent and changeless, and the basis was laid for nuclear chemistry and nuclear physics.

3.By the early 1940s nuclear reactions had been used to make radioactive isotopes of all elements; Glenn Seaborg contributed much to this work. In the 1940s and ‘50s Seaborg and his co-workers also made several elements not known to exist in nature.

4.The new elements had atomic numbers greater than 107, the atomic number of uranium.

5.By the early 21st century nuclear scientists were adding new elements to the periodic tale with atomic numbers higher than 110.

6.In the late 1920s and early 1930s, Linus Pauling contributed much to knowledge of the nature of the chemical compound.

7.He also dealt with the relationship between the structure of atoms and molecules and their properties.

Exercise 4. Answer the following questions.

1.Who discovered the phenomenon of radioactivity?

2.What happened in 1919?

3.What nuclear reactions had been used by the early 1940s?

4. When did Seaborg and his co-workers also make several elements not known to exist in nature?

5.What were these elements?

6.What Rutherford’s discovery allowed to do?

7.What was Linus Pauling’ contribution?

Exercise 5. Match the word and phrase with its definition.

11.oxygen

12.hydrogen

REFERENCES

Britannica Student Library. Encyclopedia Britannica. Chicago: Encyclopedia Britannica, 2007.

Longman Exams Dictionary. Pearson Education Limited, 2006.

The Hutchinson Educational Encyclopedia on CD-ROM, 1999.

Oxford Advanced Learner’s dictionary. Oxford University Press, 2000.

Oxford English For Information Technology. Eric H. Glendinning, John McEwan. Oxford University Press, 2002.

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НА ПУТИ В НАУЧНУЮ БИБЛИОТЕКУ

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