Planetary model of the atom

Planetary model of an atom: nucleus (red) and electrons (green)

Planetary model of the atom, or Rutherford model, - historical model of the structure of the atom, which was proposed by Ernest Rutherford as a result of an experiment with alpha particle scattering. According to this model, the atom consists of a small positively charged nucleus, in which almost all the mass of the atom is concentrated, around which electrons move, just as the planets move around the sun. The planetary model of the atom corresponds to modern ideas about the structure of the atom, taking into account the fact that the movement of electrons is of a quantum nature and is not described by the laws of classical mechanics. Historically, Rutherford's planetary model succeeded Joseph John Thomson's "plum pudding model", which postulates that negatively charged electrons are placed inside a positively charged atom.

Rutherford proposed a new model for the structure of the atom in 1911 as a conclusion from an experiment on the scattering of alpha particles on gold foil, carried out under his leadership. During this scattering, an unexpectedly large number of alpha particles were scattered at large angles, which indicated that the scattering center was small in size and a significant electric charge was concentrated in it. Rutherford's calculations showed that a scattering center, positively or negatively charged, must be at least 3000 times smaller than the size of an atom, which at that time was already known and estimated to be about 10 -10 m. Since electrons were already known at that time, and their mass and charge are determined, then the scattering center, which was later called the nucleus, must have had the opposite charge to the electrons. Rutherford did not link the amount of charge to atomic number. This conclusion was made later. And Rutherford himself suggested that the charge is proportional to the atomic mass.

The disadvantage of the planetary model was its incompatibility with the laws of classical physics. If electrons move around the nucleus like a planet around the Sun, then their movement is accelerated, and, therefore, according to the laws of classical electrodynamics, they should radiate electromagnetic waves, lose energy and fall on the nucleus. The next step in the development of the planetary model was the Bohr model, postulating other, different from the classical, laws of electron motion. Completely the contradictions of electrodynamics were able to solve quantum mechanics.

Wikimedia Foundation. 2010 .

• Eise Eisingi Planetarium
• planetary fantasy

See what the "Planetary Model of the Atom" is in other dictionaries:

planetary model of the atom- planetinis atomo modelis statusas T sritis fizika atitikmenys: angl. planetary atom model vok. Planetenmodell des Atoms, n rus. planetary model of the atom, f pranc. modele planétaire de l'atome, m … Fizikos terminų žodynas

Bohr model of the atom- Bohr model of a hydrogen-like atom (Z nuclear charge), where a negatively charged electron is enclosed in an atomic shell surrounding a small, positively charged atomic nucleus ... Wikipedia

Model (in science)- Model (French modèle, Italian modello, from Latin modulus measure, measure, sample, norm), 1) a sample that serves as a standard (standard) for serial or mass reproduction (M. car, M. clothing, etc. .), as well as the type, brand of any ... ...

Model- I Model (Model) Walter (January 24, 1891, Gentin, East Prussia, April 21, 1945, near Duisburg), Nazi German General Field Marshal (1944). In the army since 1909, participated in the 1st World War of 1914 18. From November 1940 he commanded the 3rd tank ... ... Great Soviet Encyclopedia

STRUCTURE OF THE ATOM- (see) is built from elementary particles of three types (see), (see) and (see), forming a stable system. The proton and neutron are a part of atomic (see), electrons form an electron shell. Forces act in the nucleus (see), thanks to which ... ... Great Polytechnic Encyclopedia

Atom- This term has other meanings, see Atom (meanings). Helium atom Atom (from other Greek ... Wikipedia

Rutherford Ernest- (1871 1937), English physicist, one of the creators of the theory of radioactivity and the structure of the atom, founder of a scientific school, foreign corresponding member of the Russian Academy of Sciences (1922) and honorary member of the USSR Academy of Sciences (1925). Born in New Zealand, after graduating from ... ... encyclopedic Dictionary

Άτομο

corpuscle- Helium atom Atom (another Greek ἄτομος indivisible) is the smallest part of a chemical element, which is the carrier of its properties. An atom consists of an atomic nucleus and an electron cloud surrounding it. The nucleus of an atom consists of positively charged protons and ... ... Wikipedia

corpuscles- Helium atom Atom (another Greek ἄτομος indivisible) is the smallest part of a chemical element, which is the carrier of its properties. An atom consists of an atomic nucleus and an electron cloud surrounding it. The nucleus of an atom consists of positively charged protons and ... ... Wikipedia

Books

• A set of tables. Physics. Grade 11 (15 tables), . Educational album of 15 sheets. Transformer. Electromagnetic induction in modern technology. Electronic lamps. Cathode-ray tube. Semiconductors. semiconductor diode. Transistor.…

One of the first models of the structure of the atom was proposed J. Thomson in 1904, the Atom was presented as a "sea of ​​positive electricity" with electrons oscillating in it. The total negative charge of the electrons of an electrically neutral atom was equated to its total positive charge.

Rutherford's experience

To test Thomson's hypothesis and more accurately determine the structure of the atom E. Rutherford organized a series of experiments on scattering α -particles thin metal plates - foil. In 1910 Rutherford students Hans Geiger and Ernest Marsden carried out bombing experiments α - particles of thin metal plates. They found that most α -particles pass through the foil without changing their trajectory. And this was not surprising, if we accept the correctness of Thomson's model of the atom.

Source α - radiation was placed in a lead cube with a channel drilled in it, so that it was possible to obtain a flow α -particles flying in a certain direction. Alpha particles are doubly ionized helium atoms ( Not 2+). They have a positive charge of +2 and a mass almost 7350 times the mass of an electron. Hitting a screen coated with zinc sulfide, α -particles caused it to glow, and with a magnifying glass one could see and count individual flashes that appear on the screen when each α -particles. A foil was placed between the radiation source and the screen. From the flashes on the screen it was possible to judge the scattering α -particles, i.e. about their deviation from the original direction when passing through the metal layer.

It turned out that the majority α -particles pass through the foil without changing its direction, although the thickness of the foil corresponded to hundreds of thousands of atomic diameters. But some share α -particles still deviated by small angles, and occasionally α -particles sharply changed the direction of their movement and even (about 1 in 100,000) were thrown back, as if they had encountered a massive obstacle. Cases of such a sharp deviation α -particles could be observed by moving the screen with a magnifying glass in an arc.

From the results of this experiment, the following conclusions could be drawn:

1. There is some "obstacle" in the atom, which has been called the nucleus.
2. The nucleus has a positive charge (otherwise positively charged α particles would not be reflected back).
3. The nucleus is very small compared to the size of the atom itself (only a small part α -particles changed direction).
4. The nucleus has more mass than the mass α -particles.

Rutherford explained the results of the experiment by proposing "planetary" model of the atom likened it to the solar system. According to the planetary model, in the center of the atom there is a very small nucleus, the size of which is approximately 100,000 times smaller than the size of the atom itself. This nucleus contains almost the entire mass of the atom and carries a positive charge. Electrons move around the nucleus, the number of which is determined by the charge of the nucleus. The outer trajectory of the electrons determines the outer dimensions of the atom. The diameter of an atom is about 10 -8 cm, and the diameter of the nucleus is about 10 -13 ÷10 -12 cm.

The greater the charge of the atomic nucleus, the stronger will be repelled from it α -particle, the more often there will be cases of strong deviations α -particles passing through the metal layer, from the original direction of movement. Therefore, scattering experiments α -particles make it possible not only to detect the existence of an atomic nucleus, but also to determine its charge. It already followed from Rutherford's experiments that the charge of the nucleus (expressed in units of the electron charge) is numerically equal to the ordinal number of the element in the periodic system. It's been confirmed G. Moseley, who in 1913 established a simple relationship between the wavelengths of certain lines of the X-ray spectrum of an element and its serial number, and D. Chadwick, who in 1920 determined with great accuracy the charges of atomic nuclei of a number of elements by scattering α -particles.

The physical meaning of the serial number of an element in the periodic system was established: the serial number turned out to be the most important constant of the element, expressing the positive charge of the nucleus of its atom. From the electrical neutrality of the atom, it follows that the number of electrons rotating around the nucleus is equal to the ordinal number of the element.

This discovery gave a new justification for the arrangement of elements in the periodic system. At the same time, it eliminated the apparent contradiction in Mendeleev's system - the position of some elements with a higher atomic mass ahead of elements with a lower atomic mass (tellurium and iodine, argon and potassium, cobalt and nickel). It turned out that there is no contradiction here, since the place of an element in the system is determined by the charge of the atomic nucleus. It was experimentally established that the charge of the nucleus of the tellurium atom is 52, and that of the iodine atom is 53; therefore, tellurium, despite its large atomic mass, must stand before iodine. Similarly, the charges of the nuclei of argon and potassium, nickel and cobalt fully correspond to the sequence of arrangement of these elements in the system.

So, the charge of the atomic nucleus is the main quantity on which the properties of the element and its position in the periodic system depend. That's why periodic law of Mendeleev can currently be formulated as follows:

The properties of the elements and the simple and complex substances formed by them are in a periodic dependence on the charge of the nucleus of the atoms of the elements

The determination of the serial numbers of elements by the charges of the nuclei of their atoms made it possible to establish the total number of places in the periodic system between hydrogen, which has the serial number 1, and uranium (serial number 92), which was considered at that time the last member of the periodic system of elements. When the theory of the structure of the atom was created, places 43, 61, 72, 75, 85 and 87 remained unoccupied, which indicated the possibility of the existence of yet undiscovered elements. And indeed, in 1922, the element hafnium was discovered, which took the place of 72; then in 1925 - rhenium, which took place 75. The elements that should occupy the remaining four free places in the table turned out to be radioactive and were not found in nature, but they were obtained artificially. The new elements were named technetium (number 43), promethium (61), astatine (85), and francium (87). At present, all cells of the periodic system between hydrogen and uranium are filled. However, the periodic system itself is not complete.

Atomic spectra

The planetary model was a major step in the theory of the structure of the atom. However, in some respects it contradicted well-established facts. Let's consider two such contradictions.

First, Rutherford's theory could not explain the stability of the atom. An electron revolving around a positively charged nucleus must, like an oscillating electric charge, emit electromagnetic energy in the form of light waves. But by emitting light, the electron loses some of its energy, which leads to an imbalance between the centrifugal force associated with the rotation of the electron, and the force of the electrostatic attraction of the electron to the nucleus. To restore equilibrium, the electron must move closer to the nucleus. Thus, the electron, continuously radiating electromagnetic energy and moving in a spiral, will approach the nucleus. Having exhausted all its energy, it must “fall” onto the nucleus, and the atom will cease to exist. This conclusion contradicts the real properties of atoms, which are stable formations and can exist without being destroyed for an extremely long time.

Secondly, Rutherford's model led to incorrect conclusions about the nature of atomic spectra. When light emitted by a hot solid or liquid body is passed through a glass or quartz prism, a so-called continuous spectrum is observed on a screen placed behind the prism, the visible part of which is a colored band containing all the colors of the rainbow. This phenomenon is explained by the fact that the radiation of a hot solid or liquid body consists of electromagnetic waves of various frequencies. Waves of different frequencies are not equally refracted by the prism and hit different places on the screen. The set of frequencies of electromagnetic radiation emitted by a substance is called the emission spectrum. On the other hand, substances absorb radiation of certain frequencies. The totality of the latter is called the absorption spectrum of a substance.

To obtain a spectrum, instead of a prism, you can use a diffraction grating. The latter is a glass plate, on the surface of which thin parallel strokes are applied at a very close distance from each other (up to 1500 strokes per 1 mm). Passing through such a grating, light decomposes and forms a spectrum similar to that obtained using a prism. Diffraction is inherent in any wave motion and serves as one of the main proofs of the wave nature of light.

When heated, a substance emits rays (radiation). If the radiation has one wavelength, then it is called monochromatic. In most cases, the radiation is characterized by several wavelengths. When the radiation is decomposed into monochromatic components, a radiation spectrum is obtained, where its individual components are expressed by spectral lines.

The spectra obtained by radiation from free or weakly bound atoms (for example, in gases or vapors) are called atomic spectra.

Radiation emitted by solids or liquids always gives a continuous spectrum. The radiation emitted by hot gases and vapors, in contrast to the radiation of solids and liquids, contains only certain wavelengths. Therefore, instead of a continuous strip on the screen, a series of separate colored lines separated by dark gaps is obtained. The number and location of these lines depend on the nature of the hot gas or vapor. So, potassium vapor gives - a spectrum consisting of three lines - two red and one violet; there are several red, yellow and green lines in the spectrum of calcium vapors, etc.

Radiation emitted by solids or liquids always gives a continuous spectrum. The radiation emitted by hot gases and vapors, in contrast to the radiation of solids and liquids, contains only certain wavelengths. Therefore, instead of a continuous strip on the screen, a series of separate colored lines separated by dark gaps is obtained. The number and location of these lines depend on the nature of the hot gas or vapor. So, potassium vapor gives a spectrum consisting of three lines - two red and one violet; there are several red, yellow and green lines in the spectrum of calcium vapors, etc.

Such spectra are called line spectra. It was found that the light emitted by the atoms of gases has a line spectrum, in which the spectral lines can be combined in series.

In each series, the arrangement of lines corresponds to a certain pattern. The frequencies of individual lines can be described Balmer's formula:

The fact that the atoms of each element give a completely specific spectrum inherent only to this element, and the intensity of the corresponding spectral lines is the higher, the greater the content of the element in the sample taken, is widely used to determine the qualitative and quantitative composition of substances and materials. This research method is called spectral analysis.

The planetary model of the structure of the atom turned out to be unable to explain the line emission spectrum of hydrogen atoms, and even more so the combination of spectral lines in a series. An electron revolving around the nucleus must approach the nucleus, continuously changing the speed of its movement. The frequency of the light emitted by it is determined by the frequency of its rotation and, therefore, must be continuously changing. This means that the radiation spectrum of an atom must be continuous, continuous. According to this model, the radiation frequency of an atom must be equal to the mechanical vibration frequency or be a multiple of it, which is inconsistent with the Balmer formula. Thus, Rutherford's theory could not explain either the existence of stable atoms or the presence of their line spectra.

quantum theory of light

In 1900 M. Plank showed that the ability of a heated body to emit radiation can be correctly quantitatively described only by assuming that radiant energy is emitted and absorbed by bodies not continuously, but discretely, i.e. in separate portions - quanta. At the same time, the energy E each such portion is related to the frequency of radiation by a relation called Planck's equations:

Planck himself believed for a long time that the emission and absorption of light by quanta is a property of radiating bodies, and not of the radiation itself, which is capable of having any energy and therefore could be absorbed continuously. However, in 1905 Einstein, analyzing the phenomenon of the photoelectric effect, came to the conclusion that electromagnetic (radiant) energy exists only in the form of quanta and that, therefore, radiation is a stream of indivisible material "particles" (photons), the energy of which is determined Planck's equation.

photoelectric effect The emission of electrons by a metal under the action of light incident on it is called. This phenomenon was studied in detail in 1888-1890. A. G. Stoletov. If you place the setup in a vacuum and apply to the plate M negative potential, then no current will be observed in the circuit, since there are no charged particles in the space between the plate and the grid that can carry electric current. But when the plate is illuminated with a light source, the galvanometer detects the occurrence of a current (called a photocurrent), the carriers of which are the electrons pulled out by light from the metal.

It turned out that when the light intensity changes, only the number of electrons emitted by the metal changes, i.e. photocurrent strength. But the maximum kinetic energy of each electron emitted from the metal does not depend on the intensity of illumination, but changes only when the frequency of the light incident on the metal changes. It is with an increase in the wavelength (i.e. with a decrease in frequency) that the energy of the electrons emitted by the metal decreases, and then, at a wavelength determined for each metal, the photoelectric effect disappears and does not appear even at very high light intensity. So, when illuminated with red or orange light, sodium does not show a photoelectric effect and begins to emit electrons only at a wavelength less than 590 nm (yellow light); in lithium, the photoelectric effect is found at even shorter wavelengths, starting from 516 nm (green light); and pulling out electrons from platinum under the action of visible light does not occur at all and begins only when platinum is irradiated with ultraviolet rays.

These properties of the photoelectric effect are completely inexplicable from the standpoint of the classical wave theory of light, according to which the effect should be determined (for a given metal) only by the amount of energy absorbed by the metal surface per unit time, but should not depend on the type of radiation incident on the metal. However, these same properties receive a simple and convincing explanation if we assume that the radiation consists of separate portions, photons, with a well-defined energy.

In fact, an electron in a metal is bound to the atoms of the metal, so that a certain amount of energy must be expended to pull it out. If the photon has the required amount of energy (and the energy of the photon is determined by the frequency of radiation), then the electron will be ejected, and the photoelectric effect will be observed. In the process of interaction with the metal, the photon completely gives up its energy to the electron, because the photon cannot be split into parts. The energy of the photon will be partly spent on breaking the bond between the electron and the metal, and partly on imparting the kinetic energy of motion to the electron. Therefore, the maximum kinetic energy of an electron knocked out of a metal cannot be greater than the difference between the photon energy and the binding energy of an electron with metal atoms. Consequently, with an increase in the number of photons incident on the metal surface per unit time (i.e., with an increase in the illumination intensity), only the number of electrons ejected from the metal will increase, which will lead to an increase in the photocurrent, but the energy of each electron will not increase. If the photon energy is less than the minimum energy required to eject an electron, the photoelectric effect will not be observed for any number of photons incident on the metal, i.e. at any light intensity.

quantum theory of light, developed Einstein, was able to explain not only the properties of the photoelectric effect, but also the laws of the chemical action of light, the temperature dependence of the heat capacity of solids, and a number of other phenomena. It turned out to be extremely useful in the development of ideas about the structure of atoms and molecules.

It follows from the quantum theory of light that a photon is unable to break up: it interacts as a whole with a metal electron, knocking it out of the plate; as a whole, it also interacts with the light-sensitive substance of the photographic film, causing it to darken at a certain point, and so on. In this sense, the photon behaves like a particle, i.e. exhibits corpuscular properties. However, the photon also has wave properties: this is manifested in the wave nature of the propagation of light, in the ability of the photon to interfere and diffraction. A photon differs from a particle in the classical sense of the term in that its exact position in space, like the exact position of any wave, cannot be specified. But it also differs from the "classical" wave - the inability to divide into parts. Combining corpuscular and wave properties, the photon is, strictly speaking, neither a particle nor a wave - it has a corpuscular-wave duality.

The first model of the structure of the atom was proposed by J. Thomson in 1904, according to which the atom is a positively charged sphere with electrons embedded in it. Despite its imperfection, the Thomson model made it possible to explain the phenomena of emission, absorption, and scattering of light by atoms, as well as to determine the number of electrons in atoms of light elements.

Rice. 1. Atom, according to the Thomson model. Electrons are held inside a positively charged sphere by elastic forces. Those of them that are on the surface can easily "knock out", leaving an ionized atom.

1. 2.2 Rutherford model

Thomson's model was refuted by E. Rutherford (1911), who proved that the positive charge and almost the entire mass of an atom are concentrated in a small part of its volume - the nucleus, around which electrons move (Fig. 2).

Rice. 2. This model of the structure of the atom is known as planetary, because the electrons revolve around the nucleus like the planets of the solar system.

According to the laws of classical electrodynamics, the motion of an electron in a circle around the nucleus will be stable if the Coulomb attraction force is equal to the centrifugal force. However, according to the theory of the electromagnetic field, the electrons in this case should move in a spiral, continuously radiating energy, and fall on the nucleus. However, the atom is stable.

In addition, with continuous radiation of energy, an atom should have a continuous, continuous spectrum. In fact, the spectrum of an atom consists of individual lines and series.

Thus, this model contradicts the laws of electrodynamics and does not explain the line nature of the atomic spectrum.

2.3. Bohr model

In 1913, N. Bohr proposed his theory of the structure of the atom, without completely denying the previous ideas. Bohr based his theory on two postulates.

The first postulate says that the electron can rotate around the nucleus only in certain stationary orbits. Being on them, it does not radiate or absorb energy (Fig. 3).

Rice. 3. Model of the structure of the Bohr atom. The change in the state of an atom when an electron moves from one orbit to another.

When moving along any stationary orbit, the energy supply of an electron (E 1, E 2 ...) remains constant. The closer the orbit is to the nucleus, the lower the electron energy reserve Е 1 ˂ Е 2 …˂ Е n . The energy of an electron in orbits is determined by the equation:

where m is the electron mass, h is Planck's constant, n is 1, 2, 3… (n=1 for the 1st orbit, n=2 for the 2nd, etc.).

The second postulate says that when moving from one orbit to another, an electron absorbs or releases a quantum (portion) of energy.

If atoms are exposed to influence (heating, radiation, etc.), then an electron can absorb an energy quantum and move to an orbit more distant from the nucleus (Fig. 3). In this case, one speaks of an excited state of the atom. During the reverse transition of an electron (to an orbit closer to the nucleus), energy is released in the form of a quantum of radiant energy - a photon. In the spectrum, this is fixed by a certain line. Based on the formula

,

where λ is the wavelength, n = quantum numbers characterizing the near and far orbits, Bohr calculated the wavelengths for all series in the spectrum of the hydrogen atom. The results obtained were consistent with the experimental data. The origin of discontinuous line spectra became clear. They are the result of the emission of energy by atoms during the transition of electrons from an excited state to a stationary one. Transitions of electrons to the 1st orbit form a group of frequencies of the Lyman series, to the 2nd - the Balmer series, to the 3rd Paschen series (Fig. 4, Table 1).

Rice. 4. Correspondence between electronic transitions and spectral lines of the hydrogen atom.

Table 1

Verification of the Bohr formula for series of the hydrogen spectrum

However, Bohr's theory failed to explain the splitting of lines in the spectra of multielectron atoms. Bohr proceeded from the fact that the electron is a particle, and used the laws characteristic of particles to describe the electron. At the same time, facts were accumulating that showed that the electron is also capable of exhibiting wave properties. Classical mechanics turned out to be unable to explain the motion of micro-objects, which simultaneously have the properties of material particles and the properties of a wave. This problem was solved by quantum mechanics - a physical theory that studies the general patterns of motion and interaction of microparticles with a very small mass (Table 2).

table 2

Properties of elementary particles that form an atom

Lecture: Planetary model of the atom

The structure of the atom

The most accurate way to determine the structure of any substance is spectral analysis. The radiation of each atom of an element is exclusively individual. However, before understanding how spectral analysis occurs, let's figure out what structure an atom of any element has.

The first assumption about the structure of the atom was presented by J. Thomson. This scientist has been studying atoms for a long time. Moreover, it is he who owns the discovery of the electron - for which he received the Nobel Prize. The model that Thomson proposed had nothing to do with reality, but served as a strong enough incentive for Rutherford to study the structure of the atom. The model proposed by Thomson was called "raisin pudding".

Thomson believed that the atom is a solid ball with a negative electric charge. To compensate for it, electrons are interspersed in the ball, like raisins. In sum, the charge of the electrons coincides with the charge of the entire nucleus, which makes the atom neutral.

During the study of the structure of the atom, it was found out that all atoms in solids make oscillatory motions. And, as you know, any moving particle radiates waves. That is why each atom has its own spectrum. However, these statements did not fit into the Thomson model in any way.

Rutherford's experience

To confirm or disprove Thomson's model, Rutherford proposed an experiment that resulted in the bombardment of an atom of some element by alpha particles. As a result of this experiment, it was important to see how the particle would behave.

Alpha particles were discovered as a result of the radioactive decay of radium. Their streams were alpha rays, each particle of which had a positive charge. As a result of numerous studies, it was determined that the alpha particle is like a helium atom, in which there are no electrons. Using current knowledge, we know that the alpha particle is the nucleus of helium, while Rutherford believed that these were helium ions.

Each alpha particle had tremendous energy, as a result of which it could fly at the atoms in question at high speed. Therefore, the main result of the experiment was to determine the particle deflection angle.

For the experiment, Rutherford used thin gold foil. He directed high-speed alpha particles at it. He assumed that as a result of this experiment, all particles would fly through the foil, and with small deviations. However, in order to find out for sure, he instructed his students to check if there were any large deviations in these particles.

The result of the experiment surprised absolutely everyone, because many particles not only deviated by a sufficiently large angle - some deflection angles reached more than 90 degrees.

These results surprised absolutely everyone, Rutherford said that it felt like a piece of paper was placed in the path of the projectiles, which did not allow the alpha particle to penetrate inside, as a result of which it turned back.

If the atom were really solid, then it should have some electric field, which slowed down the particle. However, the strength of the field was not enough to stop her completely, let alone push her back. This means that Thomson's model was refuted. So Rutherford started working on a new model.

Rutherford model

To get this result of the experiment, it is necessary to concentrate the positive charge in a smaller amount, resulting in a larger electric field. Using the field potential formula, you can determine the required size of a positive particle that could repel an alpha particle in the opposite direction. Its radius should be of the order of maximum 10 -15 m. That is why Rutherford proposed the planetary model of the atom.

This model is named so for a reason. The fact is that inside the atom there is a positively charged nucleus, similar to the Sun in the solar system. Electrons revolve around the nucleus like planets. The solar system is arranged in such a way that the planets are attracted to the Sun with the help of gravitational forces, however, they do not fall on the surface of the Sun as a result of the available speed that keeps them in their orbit. The same thing happens with electrons - Coulomb forces attract electrons to the nucleus, but due to rotation, they do not fall on the surface of the nucleus.

One assumption of Thomson turned out to be absolutely correct - the total charge of electrons corresponds to the charge of the nucleus. However, as a result of a strong interaction, electrons can be knocked out of their orbit, as a result of which the charge is not compensated and the atom turns into a positively charged ion.

Very important information regarding the structure of the atom is that almost all the mass of the atom is concentrated in the nucleus. For example, a hydrogen atom has only one electron, whose mass is more than one and a half thousand times less than the mass of the nucleus.