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.
