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| Radioactivity
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Chemistry: Becquerel and Curie
The discovery of radioactivity is probably one of the most
significant achievements of human science. This was a rather
complicated process and many outstanding scientists worked
on this problem. In this respect, it worth to mention Henri
Becquerel and Pierre and Marie Curie as probably the most
successful researchers in this field. At least, it is possible
to estimate that their use of the electroscope contributed
significantly to better understanding and detecting radioactive
sources.
On analysing their works, it is necessary to point out that
Henry Becquerel had actually made a great part of the job
concerning the detection of radioactive sources and radioactivity
at large but his work could hardly be fully completed without
assistance of Pierre and Marie Curie.
In this respect, it should be said that the researches of
Becquerel were the continuation of researchers of other scientists,
such as Roentgen who discovered X-Ray. Moreover, in his research
Becquerel basically followed the general procedure “exploring
various types of radiation to perform some of the experiments
that Roentgen conducted to determine the properties of X-Rays”
(Seaborg 1998, p.199). Basically, Becquerel followed this
traditional procedure since he believed that his own rays
were similar to those researched by Roentgen.
However, there was a significant difference in his experiments
aiming at detection of sources of radioactivity. Notably,
he substituted a layer of uranium salts for a cathode-ray
tube. Basically he used it in order to show that “the
separate gold leaves of an electroscope were made to fall”
(Glasstone 1969, p.337). On establishing this electrical property,
Henri Becquerel he continued his researches in order to find
out whether the rays were reflected and refracted and the
conclusion was affirmative.
His further researches with the help of electroscope revealed
the fact that uranium nitrate ceases to luminescence when
it is dissolved or melted in its water of crystallization
and the scientist “in darkness, heated crystal in a
sealed glass tube, protecting it even from the light of the
alcohol flame” (Crease and Mann 1986, p.276). Than he
allowed it to crystallize in darkness. As a result, he found
out that “all phosphorescence had been destroyed in
this process, yet the salt still produced results on a photographic
plate as strong as crystals exposed to light” (Crease
and Mann 1986, p.281). On continuing his experiments, he used
a disk of pure uranium metal and arrived to the discovery
that it produced penetrating radiation three to four time
as intense as that he had first seen potassium uranyl sulfate.
Practically at the same time, in parallel research Curie discovered
that radiations given of by uranium were composed of more
than one type, notably “some rays were bent one way
by a magnetic field; others were bent another way” (Spangenburg
and Moser 1999, p.402). Actually, scientists knew about this
fact but the problem was that nobody exactly knew what these
rays, or, to put it more precisely, particles, were composed
of, and Curie suggested the name for these radiations –
radioactivity – and that is the name that stuck.
Thus, the work of Becquerel and Curie contributed significantly
to the research of radiation and was extremely important for
the further scientific progress.
Bibliography:
1. Badash, Lawrence. “The discovery of radioactivity”,
Physics Today, February 1996.
2. Crease, Robert P. and Charles C. Mann. The Second Creation.
Affiliated East-West Press Pvt. Ltd. 1986.
3. Spangenburg, Ray and Diane K. Moser. The History of Science
from 1895-1945. Universities Press (India) Ltd. 1999.
4. Glasstone, Samuel. Sourcebook on Atomic Energy. Affiliated
East-West Press Pvt. Ltd. 1969.
5. Seaborg, Glenn. The Discovery of Radioactivity. New York:
New Publishers, 1998.
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