Planetary model of Rutherford, atom in the Rutherford model

Discoveries in the field of atomic structure have become an important step in the development of physics. Of great importance was the model of Rutherford. Atom as a system and particles, its components, was studied more accurately and in detail. This led to the successful establishment of such a science as nuclear physics.

Ancient concepts of the structure of matter

The assumption that the surrounding bodies consist of the smallest particles, were expressed even in ancient times. The thinkers of the time represented the atom in the form of a tiny and indivisible particle of any substance. They argued that there is nothing smaller in the universe than an atom. Such views were held by the great ancient Greek scholars and philosophers - Democritus, Lucretius, Epicurus. The hypotheses of these thinkers today are united under the name "ancient atomism".

Medieval views

The times of antiquity have passed, and in the Middle Ages there were also scientists who expressed various assumptions about the structure of substances. However, the prevalence of religious philosophical views and the power of the church in that period of history at the root stopped any attempts and aspirations of the human mind to materialistic scientific conclusions and discoveries. As you know, the medieval Inquisition was very unfriendly to the representatives of the scientific world of the time. It remains to say that the then bright minds had come from antiquity idea of the indivisibility of the atom.

Studies of the 18th and 19th centuries

The 18th century was marked by serious discoveries in the field of the elementary structure of matter. Largely due to the efforts of such scientists as Antoine Lavoisier, Mikhail Lomonosov and John Dalton. Regardless of each other, they managed to prove that the atoms do exist. But the question of their internal structure remained open. The end of the 18th century was marked by such a remarkable event in the scientific world as the discovery by DI Mendeleev of the periodic system of chemical elements. It became a really powerful breakthrough of that time and opened the veil over the understanding that all atoms are of the same nature, that they are related to each other. In the future, in the 19th century, another important step towards unraveling the structure of the atom was the proof that an electron exists in any of them. The work of scientists of this period prepared fertile ground for the discoveries of the 20th century.

Thomson's experiments

English physicist John Thomson in 1897 proved that the composition of atoms include electrons with a negative charge. At this stage, the false notion that the atom is the limit of the divisibility of any substance has been completely destroyed. How did Thomson manage to prove the existence of electrons? The scientist in his experiments placed electrodes in highly rarefied gases and passed an electric current. As a result, cathode rays appeared. Thomson carefully studied their features and found that they are a stream of charged particles that move at a tremendous rate. The scientist was able to calculate the mass of these particles and their charge. He also found out that they can not be converted to neutral particles, since electric charge is the basis of their nature. So the electrons were discovered. Thomson is also the creator of the first model of the atomic structure in the world. According to it, an atom is a bunch of positively charged matter in which negatively charged electrons are uniformly distributed. Such a structure explains the general neutrality of atoms, since the opposite charges counterbalance each other. The experiments of John Thomson became invaluable for further study of the structure of the atom. However, many questions remained unanswered.

Research by Rutherford

Thomson discovered the existence of electrons, but he could not find positively charged particles in the atom. Ernest Rutherford corrected this misunderstanding in 1911. During the experiments, studying the activity of alpha particles in gases, he discovered that particles are present in the atom, positively charged. Rutherford saw that when rays pass through a gas or through a thin metal plate, a small amount of particles drift from the trajectory of motion. They literally threw them back. The scientist guessed that this behavior is due to a collision with positively charged particles. Such experiments allowed the physicist to create a model of the structure of the Rutherford atom.

Planetary model

Now the views of the scientist were somewhat different from the assumptions made by John Thomson. Their models of atoms also became different. The experience of Rutherford allowed him to create a completely new theory in this area. The discoveries of the scientist were of decisive importance for the further development of physics. The Rutherford model describes the atom as a nucleus located in the center, and electrons moving around it. The nucleus has a positive charge, and the electrons - a negative one. The model of the atom according to Rutherford assumed the rotation of electrons around the nucleus along certain trajectories - orbits. The discovery of the scientist helped explain the reason for the deflection of alpha particles and became the impetus for the development of the nuclear theory of the atom. In the model of the Rutherford atom, there is an analogy with the motion of the planets of the solar system around the Sun. This is a very accurate and vivid comparison. Therefore, the Rutherford model, the atom in which it orbits the nucleus around the nucleus, was called planetary.

Works by Niels Bohr

Two years later, the Danish physicist Niels Bohr attempted to combine ideas about the structure of an atom with the quantum properties of light flux. The nuclear model of the atom of Rutherford was placed by the scientist in the basis of his new theory. According to Bohr's assumption, the atoms rotate around the nucleus along circular orbits. Such a trajectory of motion leads to an acceleration of the electrons. In addition, the Coulomb interaction of these particles with the center of the atom is accompanied by the creation and consumption of energy to maintain the spatial electromagnetic field that arises from the motion of electrons. Under such conditions, negatively charged particles should someday fall on the core. But this does not happen, which indicates a greater stability of atoms as systems. Niels Bohr realized that the laws of classical thermodynamics, described by Maxwell's equations, do not work under intra-atomic conditions. Therefore, the scientist set himself the task of deriving new laws that would be valid in the world of elementary particles.

Posterates of Bora

Largely due to the fact that there was a model of Rutherford, the atom and its components were well studied, Niels Bohr was able to approach the creation of his postulates. The first of them says that the atom has stationary states, under which it does not change its energy, and electrons move along orbits without changing their trajectory. According to the second postulate, when an electron moves from one orbit to another, energy is released or absorbed. It is equal to the difference between the energies of the preceding and subsequent states of the atom. In this case, if the electron jumps to a nearer to the nucleus orbit, then the energy is emitted (photon), and vice versa. Despite the fact that the motion of electrons does not resemble the orbital trajectory located strictly along the circumference, Bohr's discovery made it possible to obtain an excellent explanation for the existence of a line spectrum of the hydrogen atom. Approximately at the same time, physicists Hertz and Frank, who lived in Germany, confirmed Niels Bohr's doctrine of the existence of stationary, stable states of an atom and the possibility of changing the values of atomic energy.

Cooperation of two scientists

By the way, Rutherford for a long time could not determine the charge of the nucleus. The scientists Marsden and Geiger attempted to recheck Ernest Rutherford's statements and, as a result of detailed and thorough experiments and calculations, concluded that the nucleus is the most important characteristic of an atom, and its entire charge is concentrated in it. Later it was proved that the value of the nuclear charge is numerically equal to the ordinal number of the element in the periodic system of DI Mendeleev's elements. It is interesting that Niels Bohr soon became acquainted with Rutherford and fully agreed with his views. Later, the scientists worked together for a long time in the same laboratory. Rutherford's model, the atom as a system consisting of elementary charged particles, was considered by Niels Bohr to be fair and permanently put aside his electronic model. Joint scientific activity of scientists has been very successful and has borne fruit. Each of them went deep into the study of the properties of elementary particles and made important discoveries for science. Later, Rutherford discovered and proved the possibility of nuclear decomposition, but this is already the topic of another article.