History knows such cases when great ideas came to scientists quite by accident. This can also be attributed to the French physicist Henri Becquerel, who carried out the discovery of radioactivity in 1896. The reason for the experiment was the study of V. X-ray X-rays. At the same time, the scientist made the assumption that they are associated with a phenomenon such as luminescence. And it is likely that this kind of glow is impossible without cathode rays.
Becquerel decided to study the hypothesis put forward by W. Roentgen. He wondered if luminous substances could emit rays that could penetrate opaque partitions. To answer this question, Becquerel took a photographic plate, wrapped it in black film, put a copper cross covered with uranium salt on top and set it in the sun. After some time, he developed a film. It turned out that she turned black exactly in those places where the cross was. This testified to the fact that uranium is capable of creating radiation passing through opaque objects and acting on a photographic plate. At that moment A. Becquerel believed that the reason for the glow of uranium is the sun.
After some time, the scientist decided to repeat the experiment again. But this time, cloudy, inclement weather prevented him from starting the investigation. Becquerel put the plate in a black wrapper with a cross in a dark cupboard for several days. When the physicist showed the film, it turned out that, being in the dark, it blackened much more than when exposed to the sun. Investigating a large number of chemical compounds, Becquerel determined that only substances containing uranium are capable of emitting rays penetrating dark paper. So the discovery of radioactivity was made
Subsequently, this phenomenon was carefully studied by the spouses Maria Sklodowska and Pierre Curie. The discovery of radioactivity led to the study of many other elements. Pierre and Maria found that many chemicals can emit rays from three inputs: beta, alpha, gamma -. They thoroughly studied the phenomenon of radioactivity, studied its penetrating ability and behavior in a magnetic field. These discoveries allowed scientists to find the mass, speed and charge of the particles that make up the rays.
As a result of research, significant discoveries were made in the field of physics. It turned out that alpha rays consist of a huge number of relatively heavy particles, the speed of which is 16 thousand kilometers per second. Each of them has two positive charges of electricity and has a mass. Beta rays are based on electrons, or negatively charged light elements. Their speed reaches more than 300 thousand km per second. And gamma rays are similar in composition to x-rays. A little later, physicists discovered some more interesting facts. It turned out that emitting beta or alpha particles, the atoms of some chemical elements can turn into others.
As a result of the study of ores containing thorium and uranium, a completely new chemical element that was not previously studied was discovered. It received its name - polonium - in honor of Mary's native country - Poland. A little later, physicists discovered another radioactive element - radium (radiant). This component emitted rather strong radiation. In the table of D. Mendeleev, radium, having an atomic mass of 226, occupied 88 cells. A little later it was determined that chemical elements, whose serial number is more than 83, are radioactive in nature, that is, they are capable of spontaneously creating radiation.
In 1903, the Curie spouses for the discovery of radioactivity were awarded the Nobel Prize. Maria Sklodowska becomes the first female professor in history. Thanks to her, a course of lectures on the study of radioactivity is introduced for the first time at the University of Sorbonne.