The knowledge of the atom is made possible by an explanatory model, the known atomic model. It is a graphical or symbolic representation of the atom that allows us to understand the structure of all composed particles. Atomic Model
Several explanations about atoms throughout history
The first reference to the atom happened in ancient Greece through the philosopher Democritus, who stated that the atom is the smallest particle of matter, being indivisible and indestructible. His ideas were the result of an intellectual intuition rather than experimentation.
In the 19th century, British scientist John Dalton explained a series of hitherto unknown laws that are considered to be the first step in modern atomic theory. Dalton explained the law of conservation of mass, the law of constant composition and the law of multiple proportions. Dalton imagined that atoms were like compact spheres of different sizes and masses. Atomic Model
In the beginning of the 20th century, Englishman Joseph Thompson experimented with cathode rays and concluded the existence of negative particles inside the atom, calling these particles electrons. This made him think about the need for positive parts to neutralize the negative charges of the electron, for this reason, his model considers the atom as a sphere of positive matter around the negative matter. With Thompson’s contribution , the atom was given a divisible particle and, on the other hand, it was he who discovered the relationship between the mass and the electrical charge of the atom.
current atomic model
Atoms are not visible, so a theory or model is needed to understand how they work. Currently, the atom is composed of two parts: the nucleus that is in the center and the peripheral where the electrons are. The nucleus is formed by protons that have a determined mass and a positive charge and, on the other hand, neutrons that have a mass similar to that of protons, but with an electric charge of zero (for this reason they are called neutrons) . Atomic Model
In the atom’s periphery are the electrons, which have a determined mass and an electric charge equal to that of the proton , but negative. This structure of the atom is the basis of current atomic theory. To express its representation, the atom is accompanied by its atomic mass and its atomic number . The atomic number concept represents the number of protons in the atomic nucleus and the atomic mass concept represents the number of protons plus the number of neutrons in the nucleus.