Rutherford's experience

Ernest Rutherford - a unique, very talented and very unusual scientist. It should be noted that the most important discoveries were made by him after he received the Nobel Prize. In 1911, this man succeeded in the experience of Rutherford (just so he was called later), which allowed to look inside the atom and get some idea of how it is arranged.

Numerous experiments with atoms have been carried out earlier. Their main idea was to gather a sufficient amount of information from different angles of deviation of particles, according to which there would be an opportunity to say something concrete about the structure of the atom. At the beginning of the 20th century, scientists already believed that it contained electrons charged negatively. However, the most widespread at that time was the idea that the atom is similar to a positively charged thin grid, which is filled with electrons with a negative charge. This model was called a "grid with raisins."

The experience of Rutherford was unique. The scientist built a gun that gave a focused and directed stream of particles. It looked like a leaden box, in which was a narrow slot. Inside it was a radioactive material. The alpha particles, which were emitted by the radioactive material in all directions except one, were absorbed by the screen from the lead, and only through the slot a definite directed beam of particles flew out. On his way, then, several more screens of lead with slots were installed, which cut off particles deviating from the desired direction. As a result of this experience of Rutherford, a focused beam of particles flew to the target, the target itself was a very thin sheet of foil. In it, and hit the alpha-ray.

After the alpha particles collided with the atoms of the foil, they continued on their way, and eventually found themselves on a fluorescent screen that was placed behind the target. When particles hit the screen, flashes were registered on it, according to which the experimenter could judge how much and in what amount the alpha particles deviate from the direct direction of motion due to collision with the gold foil atoms .

Rutherford's experience was so original because no one before him tried to check whether certain particles deviate at great angles. The old grid model did not allow even the existence of such heavy and dense elements in the atom that they could reject 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 was actually much less dense than it seemed before. The Rutherford atom contained a superdense center, which was called the nucleus, in which, by the way, the positive charge was concentrated.

The picture of the atom, which the scientist drew, is now well known to us. Rutherford's model consists in the fact that in the center there 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 can not rest inside the atom, since they would simply fall on the core. They move around it in much the same way as planets revolve around the sun's luminary.

Such a character of the motion is determined by the actions of the Coulomb forces on the part of the nucleus. Atoms are stable, in an unexcited state they can last a long time without emitting any electromagnetic waves. However, the planetary model of the atom, although it is justified experimentally, does not allow us to explain why it is stable.