Unit 2 text a henri becquerel and the curies’ discoveries

Pre-reading tasks

1. Do you know:

1. the names of Henri Becquerel and Pierre and Marie Curie? What are they famous?

2. when the Curies and Becquerel worked?

3. what radioactive elements the Curies discovered?

4. if the Curies and Becquerel were given any award?

2. Can you guess what the word “radioactive” means? Try to give its definition.

3. Read the following statements and respond to them using the expressions: If I am not mistaken, in my opinion, to my mind and the like.

• Henri Becquerel experimented with uranium salt.

• Henri Becquerel discovered X-rays.

• Henri Becquerel found out that uranium gave off rays of unknown nature.

• Marie Curie used different minerals in her experiments.

• Marie Curie was not only a famous physicist but an outstanding chemist.

• Marie Curie managed to isolate several radioactive elements.

• Pierre Curie never conducted independent research but always helped his wife.

4. The words given in column A are in the text below. Match them with their definitions in column B.

A	B
radioactivity	take in radiations and send them out in the form of light.
to detect	find the size, extent, volume, degree , etc of smth or smb.
alien	major achievement
to fluoresce	special quality that belongs to smth
to measure	line, beam of radiant energy, heat, energy.
to extract	discover the existence or presence of smb or smth.
ray	allow to go; set free; unfasten.
to release	take or get out usually with effort or by force.
property	differing in nature or character; contrary or opposed (to).
breakthrough	process of breaking up atoms and sending out rays in the form of electrically charged particles capable of penetrating opaque bodies and of producing electrical effects.

Reading

Read the text below and

1. see in which situations mentioned in exercise 3 you were right/wrong;

2. fulfill the tasks that are given in Comprehension check.

Henri becquerel and the curies’ discoveries

X-rays were only the first, surprise of the 1890s. New rays were soon detected which proved to be even more profoundly alien to known science.

The French physicist Antoine Henri Becquerel thought that X-rays might be pr___ fluorescence. So, one by one, he took fluorescent compounds and put them on a photographic plate «rapped in black paper. He left this outside, hoping that sunlight would make the compound fluoresce and produce X-rays, which would pas-; through the paper and darken the plate. In February 1896 came a seeming success: uranium potassium sulphate.

But then, one sunless day; he put a packet away in a drawer. Weeks later when he developed the plate, it ton had darkened. Becquerel had been wrong about fluoresce. Instead, uranium was spontaneously giving off penetrating rays. Other elements did this too.

Inspired by Becquerel’s work, Marie Curie pursued the analysis of rays emitted by pitchblende, the ore from which uranium is extracted, as well as various uranium compounds between 1897 and 1898. Rather than use photographic plates, she used an electrometer (a device invented by her husband Pierre and his brother Jacques to detect extremely low electrical currents) to measure the electrical discharge of the rays in air. Using this delicate instrument in difficult conditions, Curie measured very faint currents in the air after bombarding it with uranium rays.

She later explained: It was at the close of the year 1897 that I began to study the compounds of uranium, the properties of which had greatly attracted my interest. Here was a substance emitting spontaneously and continuously radiations similar to Roentgen rays, whereas ordinarily Roentgen rays can be produced only in a vacuum-tube with the expenditure of energy. By what process can uranium furnish the same rays without expenditure of energy and without undergoing apparent modification? Is uranium the only body whose compounds emit similar rays? Such were the questions I asked myself...

In the collections of the Institut de Radium in Paris are minerals and rocks used by Marie Curie in her radiation experiments. Bombarding minerals with uranium rays, Curie discovered that the samples released energy in the form of rays. Deducing that the energy came from atoms, by 1989 Madame Curie had named the rays “radioactivity” based on the Latin word for ray. Among those shown here are carmolite, radium, lepidolite, lurite, toberinite, and rock salt. (Bridgeman Art Library)

In this fashion, Marie Curie determined that the rays were constant, and that minerals with a higher proportion of uranium emitted the strongest rays. Were the rays a product of the atomic structure of uranium? Curie believed so, hypothesizing that they were evidence of the atomic structure of uranium, and that the energy released in the form of the rays came from atoms. While not sure that the energy came from the atoms or from cosmic rays caught by atoms and reflected back (which was not the case), Curie’s work suggested that atoms were not solid, elementary particles, particularly if they shed something in the form of rays.

Working with other mineral samples, Curie found that thorium, like uranium, emitted rays. By 1898, Curie felt strongly enough that the rays were an atomic property, and she named it “radioactivity”, based on the Latin word for ray. Joined now by her husband Pierre, who set aside his own research to assist her, Marie Curie made another breakthrough:

I found, as I expected, that the minerals of uranium and thorium are radioactive; but to my great astonishment, I discovered that some are much more active than the oxides of uranium and of thorium, which they contain. Thus a specimen of pitchblende (oxide of uranium ore) was found to be four times more active than oxide of uranium itself This observation astonished me greatly. What explanation could there be for it?...The answer came to me immediately: The ore must contain a substance more radioactive than uranium and thorium, and this substance must necessarily be a chemical element as yet unknown...

Working to chemically separate the ore into separate elements, the Curies isolated two hitherto unknown and highly radioactive elements in 1898, which Marie Curie named polonium and radium. Isolating a sample of sufficient size - one tenth of a gram of pure radium chloride - took the Curies more than three years of backbreaking and expensive work. Eight tons of pitchblende, when processed, ultimately yielded a gram of radium.

Comprehension check

1. Match the discoveries and inventions with the names of scientists.

Marie Curie	found out that uranium salt emitted penetrating rays.
	invented an electrometer.
Henri Becquerel	isolated two radioactive elements and named them polonium and radium.
	found that thorium gave off rays.
Pierre Curie	yielded a gram of radium
	discovered uranium compounds that emitted very strong radiation.

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

1. X-rays

1. were detected using an electrometer.

2. and some other types of rays were discovered in the 1890s.

3. were the only surprise of the 1890s.

2. Henri Becquerel

1. used different fluorescent compounds in his experiments.

2. hoped to produce X-rays.

3. found out that fluorescing materials generated X-rays.

3. Marie Curie

1. experimented with Roentgen rays.

2. invented a new device for her experiments.

3. used an electrometer instead of photographic plates.

4. Marie Curie

1. measured very strong currents in the air after bombarding it with X-rays.

2. was inspired by Becquerel’s work and studied compounds of uranium.

3. that newly discovered rays could be produced in the same conditions as X-rays.

5. The term “radioactivity”

1. comes from Greek.

2. is based on the Latin word for ray.

3. was introduced by Pierre Curie.

6. Pierre Curie

1. always helped his wife.

2. and Marie Curie made several amazing discoveries.

3. never conducted his own research.

7. The Curies

1. managed to extract two radioactive elements in 1898.

2. isolated a number of radioactive substances from uranium pitchblends.

3. gave names to newly discovered radioactive elements.

8. In their experiments the Curies

1. had to process tons of pitchblende to get radioactive substances.

2. did not manage to separate the ore into elements.

3. used a small amount of pitchblende for isolating radioactive elements.

3. Answer the following questions.

1. What rays were discovered in the 1890s?

2. What experiments did Henri Becquerel make? What did he try to prove?

3. What did he find out as a result of his experiments?

4. What minerals did Marie Curie use in her experiments?

5. Why did she use an electrometer?

6. Why, in your opinion, did Marie Curie begin to study the compounds of uranium but not other substances?

7. What properties of uranium did Marie Curie reveal?

8. How did she explain the nature of these rays?

9. What other mineral samples did she study?

10. What did she find out as a result of her research?

11. What explanation did she give to her discoveries?

12. What new elements did the Curies isolate and what names did Marie Curie give to them?

13. What prizes did the Curies get for their work?