Text 2: Radioisotopes

An isotope is one of two or more atoms having the same number of protons in the nucleus (i.e., a number of the same chemical species and therefore exhibiting the same chemical properties), but having different atomic weights and sometimes exhibiting different radioactive properties. Isotopes are either radioactive, in which case they dissipate energy through the emission of radiation, or stable, i.e. non-radioactive.

Physicists have identified more than 800 radioisotopes. Some of them occur naturally. Most of radioisotopes are produced artificially by bombardment stable isotopes with beams of neutrons from nuclear reactions or with beams of protons or other light nuclei from particle accelerators. When a stable nucleus absorbs one of the incident particles, it becomes a different, usually radioactive nucleus.

Radioisotopes are widely used in industry and research. In some cases the radiation is used as a source of energy (as in nuclear batteries), as a thickness-measuring instrument, as a food sterilizer, as a "super X-ray" to detect flaws in metal castings, and in medicine. Since radioisotopes are chemically identical with stable isotopes of the same element, they are widely used as "tracers" in biochemical research. The tracers can be followed through the organism by means of a radiation detector.

Ex. 17. Translate the following international words.

isotope, radioisotope, emission, proton, physicist, to accelerate, acceleration, biochemistry, biochemical, organism, energy, detector

Ex. 18. Find five pairs of antonyms.

same, radioactive, artificial, stable, absorb, unstable, non-radioactive, different, to emit, natural

Ex. 19. Match the following word combinations and their translation.

A: 1. atoms having the same number of protons in the nucleus; 2. to exhibit the same chemical properties; 3. atoms having different atomic weight; 4. atoms exhibiting different radioactive properties; 5. to occur naturally

а) атоми, що виявляють різні радіоактивні властивості; b) проявляти однакові хімічні властивості; c) атоми, що мають однакову кількість протонів у ядрі; d) траплятися у природному виді; e) атоми, що мають різну атомну вагу

B: 1. to be produced artificially; 2. beams of neutrons from nuclear reactions; 3. particle accelerators; 4. a radioactive nucleus; 5. to be widely used in industry and research

а) широко використовуватись у промисловості та в наукових дослідженнях; b) радіоактивне ядро; c) прискорювачі ядерних частинок; d) отримувати штучним шляхом; e) пучки нейтронів від ядерних реакцій

Ex. 20. Answer the following questions.

1. What is an isotope?

2. What kinds of isotopes are there?

3. How many isotopes have been identified by physicists?

4. In what way are most of the radioisotopes produced?

5. Where are radioisotopes widely used?

6. Why are radioisotopes used as tracers in biochemical research?

Ex. 21. Translate the following sentences into Ukrainian.

1. 1. The elements involved varied in their properties greatly. 2. The rate of the reaction depends on the nature of the substance involved. 3. The acid involved acted as a catalyst. 4. The importance of the technique involved was evident to everyone.

2. 1. The lecture followed by practical hours took place in our club. 2. These rays uninfluenced by the magnetic field were examined by our workers. 3. The substance affected by a magnetic field must be a metal. 4. The analysis followed by an examination gave unexpected results.

3. 1. When asked about this work, he couldn't answer anything. 2. If carried out carefully, the experiment can give reliable data. 3. When shown this chart, pay attention to the figures. 1. When the composition of the substance had been determined, the scientists compared it with some other substances. 2. When they had investigated all the properties, they could state that these gases were harmful. 3. After they had separated nitrogen from other gases, they obtained it in nearly pure condition. 4. When he had found the needed solvent, he could continue his experiment.

Ex. 22. Before reading the text think and choose what answer is not correct.

1. If you heat an iron sample? It will … .

1. melt

2. change its properties temporary

3. change its composition

2. What would happen if we stop heating water?

1. it would cool

2. it would cool and freeze

3. It would evaporate

3. What should happen so that we didn’t have a chemical change?

1. acid should evaporate after heating

2. acid should dissolve an iron sample and evaporate

3. acid should be diluted with water and heated