Who proposed the nuclear model of the structure of the atom? Nuclear model of atomic structure and its scheme
The notion that atoms arethe smallest particles of matter, first emerged in the days of ancient Greece. However, it was only at the end of the 18th century, thanks to the work of such scientists as A. Lavoisier, M. V. Lomonosov and some others, that it was proved that atoms do exist. However, at that time no one asked himself what their inner structure was. Scientists still regarded atoms as indivisible "bricks", of which all matter is composed.
Attempts to explain the structure of the atom
Who suggested the nuclear model of the structure of the atomthe first of all scientists? The first attempt to create a model of these particles belonged to J. Thomson. However, it is impossible to call it successful in the full sense of the word. After all, Thomson believed that the atom is a spherical and electrically neutral system. In this case, the scientist assumed that the positive charge is distributed uniformly in the volume of this sphere, and inside it is a negatively charged core. All attempts of the scientist to explain the internal structure of the atom were unsuccessful. Ernest Rutherford is the one who proposed a nuclear model of the atomic structure a few years after Thomson put forward his theory.
History of research
With the help of an electrolysis study in 1833Faraday managed to establish that the current in the solution of electrolytes is a stream of charged particles, or ions. Based on these studies, he was able to determine the minimum ion charge. Another important role in the development of this area in physics was played by the Russian chemist DI Mendeleyev. It was he who first raised the question in scientific circles that all atoms can have the same nature. We see that before the nuclear model of the structure of the Rutherford atom was first proposed, a large number of equally important experiments were carried out by the most diverse scientists. They advanced the atomistic theory of the structure of matter forward.
The first experiments
Rutherford is really brilliantscientists, because his discoveries turned the notion of the structure of matter. In 1911, he was able to put an experiment, through which researchers could look into the mysterious depths of the atom, get an idea of what its internal structure is. The first experiments were carried out by the scientist with the support of other researchers, but the main role in the discovery belonged all the same to Rutherford.
Experiment
Using natural sources of radioactiveRutherford was able to build a cannon that emitted a stream of alpha particles. It was a box made of lead, inside which was a radioactive substance. In the gun was a slot, through which all the alpha particles hit the lead screen. They could fly out only through the slot. On the way of this beam of radioactive particles there were several more screens.
They separated particles that deviated fromthe direction specified earlier. A strictly focused alpha-particle flux was incident on the target. As a target, Rutherford used a thin sheet of gold foil. After the particles fell on this sheet, they continued their movement and eventually fell onto the luminescent screen that was installed behind this target. When alpha particles were incident on this screen, flashes were recorded, according to which the scientist could judge how many particles deviate from the original direction when colliding with the foil and what the magnitude of this deviation is.
Differences from previous experiments
Schoolchildren and students who are interested in those,who suggested a nuclear model of the structure of the atom, should know: similar experiments were conducted in physics before Rutherford. Their main idea was to gather as much information about the structure of the atom as possible from the deviations of particles from the original trajectory. All these studies led to the accumulation of a certain amount of information in science, provoked reflection on the internal structure of the smallest particles.
Already at the beginning of the twentieth century, scientists knew that inatom contains electrons that have a negative charge. But among the majority of researchers the opinion prevailed that the atom from the inside is more like a grid filled with negatively charged particles. Such experiments allowed to get a lot of information - for example, to determine the geometric dimensions of atoms.
Brilliant guess
Rutherford noticed that none of hispredecessors have never tried to determine whether alpha particles can deviate at very large angles from their trajectory. The former model, sometimes called "pudding with raisins" among scientists (because according to this model, the electrons in the atom are distributed like the puddles), simply did not allow the dense components of the structure to exist inside the atom. None of the scientists did not care to consider such an option. The researcher asked his student to re-equip the installation in such a way that large deviations of the particles from the trajectory were also fixed - only in order to exclude this possibility. What was the surprise of both the scientist and his student when it turned out that some particles fly at an angle of 180about.
What is inside the atom?
We found out who suggested the nuclear model of the structureatom and what was the experience of this scientist. At that time, Rutherford's experiment was a real breakthrough. He was forced to conclude that the bulk of the mass inside the atom is contained in a very dense substance. The scheme of the nuclear model of the structure of the atom is extremely simple: inside it is a positively charged nucleus.
Other particles, called electrons, rotatearound this nucleus. The remaining part is several orders of magnitude less dense. The arrangement of electrons inside the atom is not chaotic - the particles are arranged in order of increasing energy. The explorers called the inner parts of atoms the nuclei. The names that the scientist introduced are still used in science.
How to prepare for the lesson?
Those students who are interested in whosuggested a nuclear model of the structure of the atom, can flash in the lesson with additional knowledge. For example, you can tell how Rutherford, after a long time after his experiments, liked to give an analogy for his discovery. The South African country is smuggled with weapons for the rebels, which is enclosed in cotton bales. How can customs officers determine where the dangerous supplies are located, if the whole train is clogged with these bales? The customs officer can start shooting at the bales, and where the bullets will ricochet and there is a weapon. Rutherford stressed that this was exactly how his discovery was made.
For those who are preparing for an answer on this topic in the lesson, it is desirable to prepare answers to the following questions:
1. Who suggested the nuclear model of the structure of the atom?
2. What was the meaning of the experiment?
3. The difference between the nuclear model and other models.
The significance of Rutherford's theory
Those radical conclusions that Rutherford didfrom their experiments, forced many of his contemporaries to doubt the truth of this model. Even Rutherford himself was no exception - he published the results of his research only two years after the discovery. Taking as a basis the classical ideas about how the microparticles move, he proposed a nuclear planetary model of the structure of the atom. In general, the atom has a neutral charge. Around the nucleus, electrons move - just as the planets revolve around the sun. This movement is due to Coulomb forces. At the moment, the model of Rutherford has undergone considerable refinement, but the discovery of the scientist does not lose its relevance today.
