Ernest Rutherford is a unique, very talented and very unusual scientist. It should be noted that the most important discoveries were made to him after he received the Nobel Prize. In 1911, Rutherford's experiment (that was what he was called later) was successful for this person, which allowed him to look inside the atom and get some idea of how it is built.
Numerous experiments with atoms have been carried out before. Their main idea was to collect enough information at various angles of particle deflection, according to which it would be possible to say something specific about the structure of the atom. At the beginning of the 20th century, scientists were already convinced that it contains negatively charged electrons. However, the most widespread at that time was the idea that an atom looks like a positively charged thin network that is filled with electrons with a negative charge. This model is called "raisin net".
Rutherford's experience was unique. The scientist built a gun, which gave a focused and directed flow of particles. She looked like a lead box in which there was a narrow slot. Inside it was placed radioactive material. Alpha particles that were emitted by a radioactive substance in all but one of the directions were absorbed by a screen of lead, and only a specifically directed particle beam flew out through the slot. On his way, several more screens of lead with slots were then installed, which cut off particles deviating from the desired direction. As a result of this Rutherford experiment, a focused particle beam flew up to the target, while the target itself was a very thin sheet of foil. An alpha ray hit it.
After the alpha particles collided with the atoms of the foil, they continued on their way, and ended up on the luminescent screen that was mounted behind the target. When particles hit the screen, flashes were recorded on it, by which the experimenter could judge how much and how much alpha particles deviate from the direct direction of motion due to a collision with gold foil atoms .
Rutherford's experience was so original due to the fact that no one before him tried to check whether certain particles deviate at large angles. The old model of the grid did not even allow the existence of such heavy and dense elements in the atom that they could deflect very fast alpha particles at sufficiently large angles.
Rutherford's experience allowed us to conclude that most of the mass is concentrated in a very dense substance, which is located in the very center of the atom. The rest, in reality, turned out to be much less dense than it seemed before. Rutherford's atom contained a superdense center, which was called the nucleus, in which, by the way, a positive charge was concentrated.
The picture of the atom that the scientist painted is now well known to us. Rutherford's model is that in the center is an atomic nucleus with a positive charge, in which the entire mass of the atom is concentrated. In general, the atom is neutral. Therefore, the number of electrons inside, as well as the charge of the nucleus, is equal to the number of the element in the periodic system. It is clear that the electrons cannot rest inside the atom, since they would simply fall onto the nucleus. They move around it in much the same way that planets revolve around the sun.
This nature of the movement is determined by the actions of the Coulomb forces from the side of the nucleus. Atoms are stable, in an unexcited state they can last a long amount of time, while not emitting any electromagnetic waves. However, the planetary model of the atom, although it is experimentally justified, does not explain why it is stable.