In 1897, at the age of 30, Maria Sklodowska, who married Pierre Curie in 1895, completed her studies at the Sorbonne in Paris and was thinking about the subject of a dissertation. X-rays, discovered by William Conrad Roentgen in 1895, were still an urgent issue, but lost the charm of novelty.
On the other hand, uranium rays discovered in 1896 by Henri Becquerel caused a mysterious problem. Uranium compounds and minerals appear to be able to improve their ability to survive for several months. What was the source of this inexhaustible energy, which, apparently, violated the Carnot principle, which cannot be transformed or destroyed? Pierre Curie, already a famous physicist for his work on magnetism and crystal symmetry, felt that this phenomenon was quite unusual, and he helped his wife in solving it. Marie Curie, in the biography of Pierre Curie, confirmed: "We believe that the study of this phenomenon is very attractive, so there is a need for new bibliographic studies." And today we will find out who discovered radium.
Conductive electricity
After the initial excitement, interest in new rays quickly disappeared. One of the reasons was the spread of false or dubious observations of radiation, similar to uranium rays in various substances. No one even thought about who discovered radium. The theme was “dead” when Marie Curie entered the scene. However, for eight months in 1898, she discovered two elements: polonium and radium, creating a new scientific field - radioactivity. This brief history of discoveries goes back to three laboratories in which the works of Pierre and Marie can be distinguished from three notes published in the Proceedings of the Academy of Sciences. In addition to blackening the photographic plate, uranium rays provided air that conducts electricity. This later property was much more quantifiable. Becquerel used electroscopes, but the measurements were unreliable. This explains who discovered the radium.
Uranium rays
At this moment, there would have been no progress without the genius of Pierre Curie. If not for him, no one would have wondered who discovered radium. In 1880, together with his brother Jacques, he discovered piezoelectricity (i.e., the production of electric charges when applied to hemihedral crystals, such as quartz). He invented a device by which the charges produced by uranium in an ionization chamber were compensated for by the use of quartz. Compensation was followed by a second invention, a quadrant electrometer. The emission of uranium rays could be quantified by the weight and time required to compensate for the charges created in the ionization chamber.
First report
A report by Marie Curie was published on April 12, 1898 in the Proceedings of the Academy of Sciences: “I was looking for whether there are substances other than uranium compounds that make wiring for electricity” (Curie, M. 1898). Starting February 11, 1898, she checked all samples at hand or borrowed from various collections, including a large number of rocks and minerals. The activity of metallic uranium was taken as a reference. It was discovered that these compounds are active and that the resin blende, the massive variety of uraninite from Joachimstal ores in Austria and chalcolite, natural uranium phosphate, are more active than metallic uranium itself. And a few years later, the world found out who discovered radium and polonium.
Marie Curie noted: “This fact is quite remarkable and suggests that these minerals may contain an element that is much more active than uranium.” This artificial chalcolite is not more active than other uranium salts. At this stage, hunting for an item became a matter of paramount importance and urgency. Pierre Curie was fascinated by Marie's findings: on March 18, he left his own research projects and joined his wife in studying this issue. Now you know the answer to the question of who discovered the element of radium.
In a systematic search for Becquerel rays, Marie Curie also discovered on February 24 that thorium compounds are also active. However, German physicist Gerhardt Schmidt observed emissions a few weeks ago. Research on uranium rays has now evolved from physics to chemistry. It was necessary to separate and identify a substance whose chemical properties are unknown. However, with a hypothetical element, it was possible to monitor its radioactivity. Marie Curie explains this process: “The method we used is new to chemical studies based on radioactivity. It consists of sections performed with the usual procedures of analytical chemistry and measurements of the radioactivity of all compounds separated. "
Deposition procedures
Thus, the chemical nature of the desired radioactive element can be recognized. Neither Marie nor Pierre were chemists, so they were assisted by Gustave Bemont, who was responsible for the practical training of students at the Paris Municipal School of Physics and Physics. On April 14, the trio conducted research on a resin blende, which was more active than uranium. Several procedures were used in parallel with various precipitations and precipitations of solids, and the active substance was provided mainly with bismuth, from which it could gradually separate. On June 27, Marie Curie precipitated sulfides from a solution containing lead, bismuth and the active substance. She emphasized the result in her notebook: a solid was 300 times more active than uranium.
New radioactive substance
On July 18, Pierre Curie was 400 times more successful than uranium. Curie noted that compounds of all elements, including the rarest substances, are inactive. On July 18, 1898, Pierre and Marie Curie wrote in the Proceedings of the Academy of Sciences: “We have a new radioactive substance contained in the resin.” “We believe that the substance we extracted from the resin blende contains a previously unknown element, similar to bismuth in its analytical properties. If the existence of this new metal is confirmed, we propose to call it polonium in honor of the homeland ”(P. Curie and M. Curie 1998). The public recognized that it was Curie who discovered radium. The Po symbol, written by Pierre Curie, appears in a notebook on July 13th. The name polonium has been provocative since 1795, being divided between Prussia, Russia and the Austrian Empire.