HENRI BECQUEREL AND THE CURIES’ DISCOVERIES - раздел Иностранные языки, THE PRE_ATOMIC AGE
X-Rays Were Only The First, Surprise Of The ...
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 mineralsamples, 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 sufficientsize - 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 yieldeda gram of radium.
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Pre-reading tasks
1. The text you are to read is headlined “The Pre-atomic Age”. In your opinion, what can it run about?
2. Think of and write down 4-5 questions the answers to which you expect
THE PRE-ATOMIC AGE
Ancient Greek philosophers were the first known scientists to suggest that matter was made up of small, unseen elements, a theory described as “atomism” by Democritus of Abdera in the 5th century В
Comprehension check
1. Choose the best ending a, b, or c to complete the sentences.
1. Ancient Greek philosophers
a) were the first to suppose that matter was composed of small
Vocabulary work
1. The words given in A are used in the text above. Find their synonyms in B.
A
B
to suggest
Pre-reading tasks
1. Have you ever heard about John Dalton, Heinrich Geissler, William Crookes?
2. Can you recollect what they are famous for? What contributions to science did they make?
Comprehension check
1. Consult the text above and complete the following sentences.
1. Atomism reentered scientific ... in the 19th century.
2. Dalto
Pre-reading tasks
1. Do you know:
a) the names of Henri Becquerel and Pierre and Marie Curie? What are they famous?
b) when the Curies and Becquerel worked?
c) what
Comprehension check
1. Match the discoveries and inventions with the names of scientists.
Marie Curie
found out that uranium salt emitted pen
Vocabulary work
1. There are some words given in bold type in the text. Choose their synonyms in the box below.
to emit
to discover
Pre-reading tasks
1. The text you are going to read is headlined “Further advances in the field of radioactivity”. In your opinion,
- what does it run about?
- what
FURTHER ADVANCES IN THE FIELD OF RADIOACTIVITY
Their work, which led to the Nobel Prize for both (and two prizes for Marie, a rare honor), confirmed the cathode-ray research of British scientist J. J.Thomson, who had experimente
RADIOACTIVITY AND RADIOACTIVE EXPOSURES
Radioactivity and the associated radiation exposures are sometimes thought of as environmental problems that have been created by modern science and technology. However, substantial
Pre-reading tasks
1. If you were asked to make a report on the theme “From nuclear reactions to nuclear fission” which events would you include in it and what scientists would you mention? Comment
FROM NUCLEAR REACTIONS TO NUCLEAR FISSION
In 1913, Neils Bohr, a brilliant Danish physicist and a post-doctoral student of Rutherford’s, elaborated and modified Rutherford’s model by incorporating quantum mechanical (the study of mechanica
Comprehension check
1. Some dates, namely years are mentioned in the text. Match them with the events described.
J. Chadwick discovered the
Vocabulary work
1. The words given in two columns of the box are mentioned in the text and they have similar meanings. Find and name these pairs.
A
Pre-reading tasks
1. The paragraphs of the text given below are jumbled. Arrange them in the logical order. Comment on your choice of paragraphs succession.
2. You are sure to know the name of a f
SPECULATIONS BEFORE THE DISCOVERY OF FUSION
Atomic energy, now usually called nuclear energy, became a gleam in the eye of scientists in the early part of the 20th century. The possibility that the atom held a vast
Pre-reading tasks
1. Otto Hahn, Lise Meitner, Fritz Strassman made several key breakthroughs revealing secrets of nuclear fission. Can you give any information about these scientists? If nothing is known to you,
REVEALING SECRETS OF NUCLEAR FISSION
Enrico Fermi and his colleagues missed a reaction in the uranium which would later be determined to be the first example of nuclear fission. The task, therefore, fell tо scientist Otto Hahn, who wa
Comprehension check
1. Match the names of scientists with the information about them. (Sometimes information refers to more than one scientist).
Otto Hahn
co
Vocabulary work
1. Find synonyms or antonyms among the words given in italics in the text and name them. Be careful as the verbs are used in different forms
2. Fill in the tab
Follow-up activities
1. In pairs, discuss the information given in the text.
2. Make up a short report based on the text. (Presenting only key ideas).
3. Find some add
FISSION AND THE FIRST REACTORS
Fission of uranium was discovered—or, more precisely, recognized for what it was—in 1938. Scientists quickly recognized that large amounts of energy are released in fission and that
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
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 … . Ra
Pre-reading tasks
1. The text you are to read is headlined “Boiling water reactors”. In your opinion, what problems are discussed in this text?
2. If you were to make a report on this theme wha
BOILING WATER REACTORS
Consider the simplified schematic of one of the most common types of nuclear reactor, a boiling water reactor. (See the accompanying illustration.) Boiling water reactors were firs
GLOBAL WARMING AND NUCLEAR POWER
The idea behind global warming is simple enough. Earth’s atmosphere retains some of the heat that Earth receives from the Sun. The amount of heat retained depends upon the chemical composition of t
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