Unit 5 text a radioactive materials as sources of nuclear energy

Pre-reading tasks

1. In the text below the names of Henri Becquerel, Pierre and Marie Curie, Ernest Rutherford are mentioned. Recollect what each of them is famous for. The table below will help you to fulfill the task. If possible, add some more facts.

Henri Becquerel	coined the term radioactivity.
	created the ionization chamber for detecting and measuring radioactivity.
Marie Curie	identified two types of rays – alpha and beta radiation.
	determined that once seemingly impenetrable atom was a series of electrons that orbited a nucleus.
Pierre Curie	used fluorescent compounds, namely uranium salt in his experiment.
	isolated two radioactive elements – radium and polonium.
Ernest Rutherford	discovered that uranium compounds when placed on photographic plates gave off penetrating rays.

2. Explain the following phenomena:

• radioactive decay,

• radioactivity,

• radiation.

3. The following verbs – make, carry out, conduct, perform, run – can be combined with the noun experiment. Think of sentences in which either of these verbs will be used. Your sentences must contain the true information about experiments made by H. Becquerel, the Curies, E. Rutherford.

Reading

Read the text and fulfill the tasks to follow.

Radioactive materials as sources of nuclear energy

Radioactive … involves the spontaneous disintegration of an atomic nucleus. As the nucleus …, various particles as well as high-energy electromagnetic waves are … . Radioactivity is not a new … . Radioactive materials have always been present everywhere in the … —in the atmosphere, on land, and in the oceans—but until the latter years of the 19^th century the phenomenon of … had escaped scientific attention because it usually exists at such low levels that its effects are difficult … .

As a subject of scientific interest, radioactivity came to the fore when the French scientist Antoine-Henri Becquerel (1852–1908) … a series of experiments whose purpose was to investigate X-rays. In these experiments he wrapped … photographic plates in … paper so that no light could reach them and placed certain materials near the wrapped plates. He discovered that when he placed compounds … the metal uranium near the plates, they emitted rays that passed through the paper and exposed the plates. He found that he could take primitive pictures with these … . By placing a coin between the material emitting the rays and the photographic plate, for example, he found that the coin blocked the rays. The result was that the plate was exposed everywhere except for the area beneath the coin. Although he misinterpreted the nature of the phenomenon he had discovered, his results attracted the attention of the most successful husband-and-wife team in the history of science, the French scientist Pierre Curie (1859–1906) and the Polish-born scientist Marie Curie (1867–1934). (Marie Curie later coined the term radioactivity.)

The phenomenon observed by Becquerel was a weak one because natural uranium emits few radioactive particles per unit time. Scientists describe this situation by saying that natural uranium has a low specific activity. Intrigued by Becquerel’s experiments, Marie Curie began to investigate the mineral pitchblende, which has a higher specific activity than uranium.

While Pierre Curie concentrated on identifying the physical properties of radiation, Marie sought to isolate the elements responsible for emitting the higher levels of radiation. Her work culminated in the discovery of two new elements, polonium and radium. The element radium was of particular interest because compared to uranium, radium has a very high specific activity; in other words, a unit mass of radium emits a great deal more radioactivity per unit time than does a unit mass of natural uranium.

Physicists of the time were astonished by what Marie Curie had discovered. Not only did the radium continuously emit relatively large amounts of energy, but it emitted the energy for long periods of time without changing in any perceptible way. Keep in mind that the principle of conservation of energy, which states that energy can neither be created nor destroyed, meant that energy was, in effect, draining away from her sample of radium. As Curie knew, this continual emission of energy must eventually leave a perceptible change in the physical properties of her radium sample. The fact that she could not quickly detect any change in the radium meant that the amount of energy contained in a small piece of radium must be very large. In 1904, Marie Curie expressed her insights in these words:

“Radium possesses the remarkable property of liberating heat spontaneously and continuously. A solid salt of radium develops a quantity of heat such that for each gram of radium contained in the salt there is an emission of one hundred calories per hour. Expressed differently, radium can melt in an hour its weight in ice. When we reflect that radium acts in this manner continuously, we are amazed at the amount of heat produced, for it can be explained by no known chemical reaction. The radium remains apparently unchanged. If, then, we assume that it undergoes a transformation, we must therefore conclude that the change is extremely slow, in an hour it is impossible to detect a change by any known methods.”

The ability of radium to emit large quantities of energy for prolonged times without perceptible change led the British physicist Ernest Rutherford (1871–1937) to speculate on the possibility of harnessing radioactive materials for warfare and for work. If one could release all of the energy at once, he wrote, one could create a tremendous bomb. This, after all, is what a bomb does: It releases a great deal of energy over a very short period of time. If, on the other hand, one could increase the rate of energy release in a gradual and controlled way, one would have a source of power sufficient to supply the largest of cities with its power needs. If only one could control the rate at which radium emitted its energy, Rutherford speculated, a small mass of radium could replace a very large mass of coal.

In principle, Rutherford was right. Nor was he alone. The British writer H. G. Wells (1866–1946) had the same sorts of insights. But while their instincts were correct, Rutherford and his contemporaries were wrong about the power source. It would not be radium that would power cities and serve as fuel for a new and more powerful type of bomb but rather the radioactive metals uranium and the yet-to-be-created plutonium.

Tasks

1. Fill in the blanks in the first two paragraphs of the text choosing suitable words from the box.

released	decay	phenomenon	to observe	rays	performed
radioactivity	opaque	containing	disintegrates	unexposed	environment

2. The adjectives given in the box have their antonyms or synonyms mentioned in the text. Find and name them. (There is sometimes more than one equivalent).

transparent	typical	occasional	characteristic	sophisticated	fortunate
diverse	commonplace	different	enormous	ordinary	colossal
reliable	lucky	huge	doubtful	trustworthy	irregular

3. Insert suitable prepositions.

1. Radioactivity came … the fore when Becquerel made a number of experiments investigating X-rays.

2. He wrapped plates … opaque paper.

3. Rays passed … the paper.

4. He concentrated … studying the properties of uranium.

5. Compared … radium, uranium has a low specific activity.

6. She is responsible … conducting these experiments.

7. Keep … mind that this law holds in all cases.

8. This substance can melt … an hour.

9. … principle he is right.

10. It can supply the largest cities … power.

11. … the other hand, we could increase the rate of energy release in a gradual way.

4. Complete the sentences choosing the best ending a, b, or c.

1. Radioactivity decay

1. is a spontaneous disintegration of atoms.

2. is a process during which nuclei disintegrate.

3. involves decomposition of molecules.

2. As a result of the nucleus disintegration

1. neutrons are given off.

2. penetrating rays are emitted.

3. different particles and high-energy electromagnetic waves are released.

3. Radioactivity

1. is easy to observe.

2. has always been present everywhere in the environment.

3. is a phenomenon that has been known to scientists for a long time.

4. Henri Becquerel

1. investigated X-rays.

2. used different devices in his experiments to detect and measure radioactivity.

3. explained the nature of radioactivity.

5. Marie Curie

1. preferred to investigate natural uranium.

2. chose mineral pitchblende for her initial experiments as it has a higher specific activity.

3. tried to determine chemical properties of different radioactive substances.

6. Pierre Curie

1. isolated two new radioactive elements – radium and polonium.

2. revealed the properties of radium and polonium.

3. focused his work on determining the physical properties of radiation.

7. The principle of energy conservation states that

1. energy can neither appear nor disappear.

2. nuclear energy cannot be converted into other forms.

3. energy can be created but cannot be destroyed.

8. Rutherford

1. and his contemporaries were right about the power source.

2. thought that radium would serve as a new type of fuel.

3. was right in his speculations on the possibility of harnessing radioactive materials for military and peaceful purposes.

5. There are some factual mistakes in the sentences to follow. Find them and correct. Be careful as two sentences are correct.

1. Radioactive materials are present only in the atmosphere.

2. The phenomenon of radioactivity has always been familiar to scientists as it is easy to observe.

3. Henri Becquerel discovered that photographic plates were not affected by emitted rays.

4. Natural uranium is a highly radioactive material.

5. A small piece of radium contains a great amount of energy.

6. The Curies investigated polonium in their initial experiments.

7. Ernest Rutherford thought that radioactive materials could be used for creating a bomb.

8. Radium emits larger amount of energy that uranium but this energy emission lasts for a shorter period of time.

9. Ernest Rutherford considered radium and uranium to be power sources.

6. Imagine you were

1. Henri Becquerel. You want to describe the experiments performed. Make use of the information of the text to fulfill the task. If necessary, add some more facts.

2. Marie Curie. You are inspired by Becquerel’s experiments. You want to reveal secrets of the phenomenon observed by Becquerel. Speak about your experiments and their results. Don’t forget to characterize the newly discovered radioactive substances radium and polonium.

3. Ernest Rutherford. Speculate on possibilities of using radioactive materials for military and peaceful purposes.

7. Organize a round-table discussion. Invite Henri Becquerel, Pierre and Marie Curie, Ernest Rutherford to take part in it. Interview them for the results of their work.