Atomic models have been suggested, since antiquity, by Greeks such as Democritus of Abdera (420 a. C.) and Leucipus (450 a. C.), who already stated that matter was composed of small particles that received the name of atom, a word that in Greek means indivisible. This model is a philosophical model with no definite form and no core, and it has no scientific basis.
Since then it has gone through models proposed by Dalton (1803) and by thomson (1898), until reaching the most current model that was created by Rutherford, in 1911. According to him, the atom consists of a small nucleus that comprises all the positive charge and practically the mass of the atom, and also of an extranuclear region which is an empty space where there are only electrons distributed.
Later, in 1914, Rutherford conceptualized the atomic nucleus, which is a particle that has a mass greater than that of the electron, but when it comes to charge, the nucleus and the electron have equal charges, but with opposite signs. Electrons have a negative charge and the nucleus has a positive charge.
Rutherford, in 1920, stated that this positive charge is due to the presence of protons, a name proposed by him. In 1913, the atom underwent an improvement carried out by the Danish physicist Niels Bohr, which divided the electrosphere into seven layers, now called valence layers.
By Líria Alves
Graduated in Chemistry
See more:
Thomson's atom
Atom model nicknamed “Plum Pudding”.
Rutherford's Atom
Discover the experiment that gave rise to this theory.
Source: Brazil School - https://brasilescola.uol.com.br/quimica/evolucao-modelo-atomico.htm
