An Atomic Model is a graphic representation that allows us to explain, as best as possible, the structure of the atom. As is well known, atoms are representations, because nobody has seen them; They are deduced from experiments, which evolve with technology. In ancient Greece, the first philosophers believed that matter was made up of tiny indestructible particles, which they called atoms . It was only; However, of a philosophical doctrine, which did not achieve universal acceptance due to lack of experimental evidence. Towards 1803, the Englishman John Dalton developed a model where he assumed that all matter is composed of atoms; which he represented asSpherical particles full of mass and of variable size, depending on the element to which they belonged, but indivisible, indestructible and therefore eternal.
Approximately a century later, it would be found that the atom is not indivisible and that all the atoms of the same element do not have the same mass and therefore are not equal. With the discovery of electrons and cathode rays, I quickly led to the imagination of a structure for the atom.
The first hypothesis established was in 1904 by JJ Thomson, by supposing that the atom was constituted by a material sphere, but with a positive electric charge, within which the electrons necessary to neutralize said charge were embedded.
Later, the experiments carried out by the physicist Ernest Rutherford led him to deduce that the positive charge of an atom and most of its mass are concentrated in a small central region called the nucleus . In his model, electrons, negatively charged, revolved around the nucleus like planets around the Sun.
In 1913, the Danish physicist Niels Bohr, supported by Max Planck's quantum theory, discovered that the electrons in an atom can only have certain energy levels. He proposed that the energy of an electron was related to the distance from its orbit to the nucleus. Therefore, the electrons only circled the nucleus at certain distances, in "quantized orbits", corresponding to the allowed energies.
Later, Arnold Sommerfield modified Bohr's theory to state that electrons could rotate in elliptical orbits. In these, as the electron approached the nucleus, in order not to be captured it had to move faster. When doing it according to the works of Einstein, its mass would increase modifying its trajectory.
Starting in 1926, in the light of the works of Heisenberg, De Broglie, Schrödinger, Born and Dirac, electrons were no longer conceived as particles rotating in orbits. The concept of orbit was replaced by orbital, which is a mathematical function that allows us to know information about the small region of space around the nucleus where the electron is most likely to be found. These regions can differ in size, shape, special orientation, and energy.
