Ernest Rutherford is one of the founders of the fundamental doctrine of the internal structure of the atom. A scientist was born in England in a family of immigrants from Scotland. Rutherford was the fourth child in his family, while he turned out to be the most talented. He managed to make a special contribution to the theory of the structure of the atom.
Initial ideas about the structure of the atom
It should be noted that before the well-known experiment of Rutherford on the scattering of alpha particles, the prevailing idea of the structure of the atom at that time was the Thompson model. This scientist was sure that a positive charge uniformly filled the entire atomic volume. Negatively charged electrons, Thompson believed, were as if interspersed in it.
Background to the scientific revolution
After leaving school, Rutherford as the most talented student received a grant of 50 pounds for further studies. Thanks to this, he managed to go to college in New Zealand. Further, the young scientist passes exams at the University of Canterbury and begins to seriously engage in physics and chemistry. In 1891, Rutherford made his first lecture on the theme “Evolution of the Elements”. For the first time in history, it outlined the idea that atoms are complex structures.
Then, in scientific circles, Dalton’s idea that atoms were indivisible prevailed. To everyone around Rutherford, his idea seemed utterly insane. The young scientist had to constantly apologize to his colleagues for their "nonsense." But after 12 years, Rutherford still managed to prove his case. Rutherford had a chance to continue his research at the Cavendish Laboratory in England, where he began to study the processes of air ionization. Rutherford's first discovery was alpha and beta rays.
Rutherford Experience
Briefly about the discovery, you can tell this: in 1912, Rutherford, together with his assistants, conducted his famous experiment - alpha particles were emitted from a lead source. All particles, except those that were absorbed by lead, moved along the established channel. Their narrow stream fell on a thin layer of foil. This line was perpendicular to the sheet. Rutherford's experience in scattering alpha particles proved that those particles that passed through a sheet of foil through caused a so-called scintillation on the screen.
This screen was covered with a special substance that began to glow when alpha particles hit it. The space between the gold foil layer and the screen was filled with vacuum so that alpha particles do not scatter in the air. Such a device allowed researchers to observe particles scattering at an angle of about 150 °.
If the foil was not used as an obstacle in front of the beam of alpha particles, a light circle of scintillations formed on the screen. But as soon as a golden foil barrier was placed in front of their beam, the picture changed greatly. Flashes appeared not only outside this circle, but also on the opposite side of the foil. Rutherford's experience with alpha particle scattering showed that most particles pass through the foil without noticeable changes in the trajectory of motion.
At the same time, some particles were deflected at a rather large angle and were even thrown back. For every 10,000 particles freely passing through a layer of gold foil, only one deflected by an angle exceeding 10 ° - as an exception, one of the particles deflected by such an angle.
The reason alpha particles deflected
What Rutherford's experience examined and proved in detail is the structure of the atom. This situation indicated that the atom is not a continuous formation. Most particles passed freely through a single atom thick foil. And since the mass of the alpha particle is almost 8,000 times the mass of the electron, the latter could not significantly affect the trajectory of the alpha particle. This could be done only by an atomic nucleus - a body of small size, possessing almost the entire mass and the entire electric charge of the atom. At that time, this was a significant breakthrough for the English physicist. Rutherford's experience is considered one of the most important steps in the formation of the science of the internal structure of an atom.
Other discoveries from atom research
These studies have become direct evidence that the positive charge of an atom is inside its nucleus. This area occupies a very small space compared to its integral dimensions. In such a small volume, scattering of alpha particles was very unlikely. And those particles that passed near the region of the atomic nucleus experienced sharp deviations from the trajectory, because the repulsive forces between the alpha particle and the nucleus of the atom were very powerful. Rutherford’s experience with alpha particle scattering proved the likelihood that the alpha particle would hit directly into the nucleus. True, the probability was very small, but still not equal to zero.
This was not the only fact that Rutherford's experience proved. Briefly, the structure of the atom was studied by his colleagues, who made a number of other important discoveries. In addition to the teaching that alpha particles are fast-moving helium nuclei.
The scientist was able to describe the structure of the atom, in which the core occupies an insignificant part of the entire volume. His experiments proved that almost the entire charge of an atom is concentrated inside its nucleus. In this case, both cases of deflection of alpha particles and cases of their collision with the nucleus occur.
Rutherford's experiments: nuclear model of the atom
In 1911, Rutherford, after numerous studies, proposed a model of the structure of the atom, which he called planetary. According to this model, a nucleus is located inside the atom, which contains almost the entire mass of the particle. Electrons move around the nucleus just like planets around the sun do. From their totality, the so-called electron cloud is formed. The atom has a neutral charge, as shown by the experience of Rutherford.
The structure of the atom subsequently interested a scientist named Niels Bohr. It was he who finalized the teachings of Rutherford, because before Bohr, the planetary model of the atom began to encounter difficulties in explaining. Since the electron moves around the nucleus in a specific orbit with acceleration, sooner or later it must fall on the nucleus of the atom. However, Niels Bohr was able to prove that the laws of classical mechanics no longer apply inside an atom.