Radioactive transformations of atomic nuclei: the history of discovery, the main types of transformations

The discovery of the structure of the atomic nucleus was one of the most important stages in the development of modern physical knowledge. Scientists came to the right conclusions about the structure of the smallest particles not immediately. And much later, other regularities were discovered-for example, the laws of the movement of microparticles, as well as the features of the transformation of atomic nuclei that occur during radioactive decay.

Rutherford's experiments

For the first time radioactive transformations of atomic nuclei were studied by the English researcher Rutherford. Even then it was clear that the bulk of the atom is in its nucleus, since electrons are many hundreds of times lighter than nucleons. In order to investigate the positive charge inside the nucleus, in 1906, Rutherford proposed to investigate the atom by probing with alpha particles. Such particles appeared in the decay of radium, as well as some other substances. In the course of his experiments, Rutherford got an idea of the structure of the atom, which was given the name of a "planetary model."

The first observations of radioactivity

Back in 1985, the English explorer W. Ramsay, who is known for his discovery of argon gas, made an interesting discovery. In a mineral called kleveit he discovered a helium gas. Subsequently, a large amount of helium was also found in other minerals, but only in those containing thorium and uranium.

The researcher seemed very strange: where could the gas come from in the minerals? But when Rutherford began to study the nature of radioactivity, it turned out that helium is a product of radioactive decay. Some chemical elements "generate" others, with completely new properties. And this fact contradicted all the previous experience of chemists of that time.

Observation of Frederick Soddy

Together with Rutherford in the research was directly involved scientist Frederick Soddy. He was a chemist, and therefore all his work was carried out with regard to the identification of chemical elements according to their properties. In fact, radioactive transformations of atomic nuclei were first observed by Soddy. He was able to figure out what the alpha particles that Rutherford used in his experiments are. After making the measurements, the scientists found out that the mass of one alpha particle is 4 atomic mass units. Having accumulated a certain number of such alpha particles, the researchers found that they had turned into a new substance - helium. The properties of this gas were well known to Soddy. Therefore, he argued that the alpha particles managed to capture electrons from the outside and turn into neutral helium atoms.

Changes inside the nucleus of the atom

Subsequent studies were aimed at identifying features of the atomic nucleus. Scientists realized that all transformations do not take place with electrons or the electron shell, but directly with the nuclei themselves. It was the radioactive transformations of atomic nuclei that facilitated the transformation of certain substances into others. Then the details of these transformations were unknown to scientists. But it was clear that somehow new chemical elements appeared in their result.

For the first time such a chain of metamorphoses could be traced by scientists in the process of converting radium into radon. The reactions, which resulted in such transformations, accompanied by special radiation, the researchers called nuclear. Convinced that all these processes take place within the nucleus of the atom, scientists began to explore other substances, not just radium.

Open types of radiation

The main discipline that can require answers to such questions is physics (9th grade). Radioactive transformations of atomic nuclei are included in its course. Carrying out experiments on the penetrating ability of uranium radiation, Rutherford discovered two types of radiation, or radioactive transformations. A less penetrating type was called alpha radiation. Later, beta radiation was also investigated. Gamma radiation was first studied by Paul Willard in 1900. Scientists have shown that the phenomenon of radioactivity is associated with the decay of atomic nuclei. Thus, according to the prevailing ideas of the atom as an indivisible particle, a devastating blow was struck.

Radioactive transformations of atomic nuclei: basic types

It is now believed that during the radioactive decay there are three types of transformations: alpha-decay, beta decay, electronic capture, otherwise called K-capture. In alpha decay, an alpha particle emits from the nucleus, which is the nucleus of the helium atom. The radioactive nucleus itself turns into one that has a smaller electric charge. Alpha decay is characteristic of substances occupying the last places in the periodic table. Beta-decay also enters into radioactive transformations of atomic nuclei. The composition of the atomic nucleus under this type also varies: it loses neutrinos or antineutrinos, as well as electrons and positrons.

This type of decay is accompanied by short-wave electromagnetic radiation. In electron capture, the nucleus of an atom absorbs one of the nearest electrons. In this case, the core of beryllium can turn into a nucleus of lithium. This type was discovered in 1938 by a physicist from America named Alvarez, who also studied radioactive transformations of atomic nuclei. Photos, on which researchers tried to capture such processes, contain images similar to a blurry cloud, because of the small values of the particles being studied.