He Dalton's atomic model or Dalton's atomic theory , was a proposal presented between 1803 and 1807 by the English chemist and mathematician John Dalton.
This was the first proposal of conceptual organization regarding the structure and functioning of atoms. The Dalton model is also known as a spherical model, since it proposes the fact that the atom is an indivisible, solid and compact sphere.
Thanks to this model it was much easier to provide an explanation about chemistry to the rest of the world and it was the basis of the many innovative research projects that followed. It was possible to explain why the substances reacted in certain states.
According to Dalton, the matter was composed of a minimal unit called atom, which could not be destroyed or divided in any way.
This unit formerly proposed by Democritus and his mentor Leucipo, was the basis of Dalton's research and the creation of his atomic model.
With this atomic theory John Dalton tried to return to the ideas of the Greek philosophers on the existence of the atom (atomic theory of the universe), but using as a platform various laboratory experiments that allowed him to demonstrate his ideas.
In this model, Dalton proposed 6 nominations to explain some enigmas of nature.
John Dalton
John Dalton He was an English chemist, mathematician and chemist. He was born on September 6, 1766 in Cumberland, United Kingdom, and is known as one of the precursors of atomic theories from the moment he presented his Atomic Model.
Likewise, Dalton is known as one of the precursors in the creation of a table of relative weights for chemical elements. This fact helped to lay the foundations of what we know today as modern chemistry.
Dalton was the first scientist who had the honor of publishing a table of atomic weights that included elements such as hydrogen, oxygen, phosphorus, carbon and sulfur. Thanks to this publication, Dalton began to work and shape what would be his atomic model.
It should be noted that Dalton was one of the first people registered with visual problems to capture the colors and due to him this condition is named colour blindness . The scientist died of a heart attack on July 27, 1884 in Manchester and soon after received honors from the monarchy.
His contribution to the world of science was mainly to clarify and formulate hypotheses about nature through quantitative tests.
Postulates of the Dalton Atomic Model
Dalton formulated his atomic model with 6 postulates in which he explains in what he based his studies and how he carried them out.
Postulate 1
Dalton's first postulate stated that the elements are made up of tiny particles called atoms, which can not be divided nor can they be destroyed.
Likewise, Dalton commented that these particles could not change in any chemical reaction .
Postulate 2
The second postulate of Dalton established that all the atoms present in a same element are equal in weight as in other characteristics.
On the other hand, it also established that the atoms of different elements have different mass. From this proposal came the knowledge of the relative atomic weights that were demonstrated when comparing different elements with hydrogen.
Postulate 3
The third postulate of Dalton established that atoms are indivisible even when they are combined in chemical reactions.
The combination of atoms, both equal and different, will generate more complex compounds, but this process will not change the fact that the atom is the minimum unit of matter.
Postulate 4
The fourth postulate of Dalton stated that even when atoms are combined to form a compound, they will always have a relationship that can be expressed in simple and complete numbers. This expression will not be shown in fractions, since the atoms are indivisible.
Postulate 5
Dalton's fifth postulate stated that there is a possible combination of different atoms in different proportions to form more than one compound.
In this way, it could be explained that from a finite amount of atoms all the matter existing in the universe has come from.
Postulate 6
The sixth and last postulate of Dalton established that each and every one of the chemical compounds were created from the combination of the atoms of two or more different elements.
Errors of the Dalton Atomic Model
Like all theory in the world of science, there were many refutations with respect to the model proposed by Dalton, which were demonstrated over the years leaving behind the innovative ideas of Dalton.
Water formula
An example of this was Dalton's argument about the water formula, which he said was composed of hydrogen and oxygen.
Due to this statement there were many calculation errors with respect to the mass and weight of some basic compounds that were based on that information.
A few years later, European scientists Gay-Lussac and Alexander von Humbodt refuted this information and proved that water was actually composed of two hydrogens and one oxygen. 6 years later Amadeo Avogadro pointed out the exact composition of the water and because of it there is Avogadro's Law.
Composition of atoms
On the other hand, in the twentieth century the true composition of atoms was revealed. In this case it was shown that there is a smaller unit such as protons, electrons and neutrons.
Likewise, the existence of the different atomic weights established in the periodic table of Mendeleyev and Meyer, the existence of isotopes and the more specific chemical properties came to light.
Conclusions
Despite his mistakes, the contributions of John Dalton were of great relevance in the world of science and caused a stir in his time due to the large amount of information he provided.
Your scientific contributions are still valid and are still being studied today.
Dalton's atomic model was not questioned for decades due to its relevance in the world of science and its correct explanation to the investigations and hypotheses that were presented at that moment in the history of science.
References
- Dalton's atomic theory. Retrieved on November 24, 2017, from Khanacademy: www.khanacademy.org
- Dalton's Atomic Theory. Retrieved on November 24, 2017, from Indiana University Northwest: iun.edu
- Atomic theory. Retrieved on November 24, 2017, from Encyclopædia Britannica: www.britannica.com
- Atomic Theory. Retrieved on November 24, 2017, from Wikipedia: en.wikipedia.org
- History of Atomic Structure. Retrieved on November 24, 2017, from Lumen: courses.lumenlearning.com.