Dalton's Atomic Theory

We explain what Dalton's Atomic Theory is, the atomic model it proposes, and its importance. Also, who was John Dalton.

Dalton's atomic theory physics chemistry science atom elements
Dalton discovered that all matter is made up of a limited number of atoms.

What is Dalton's Atomic Theory?

It is known as the Dalton's atomic theory or the Dalton's atomic model to the first model of scientific bases regarding the fundamental structure of matter. It was postulated between 1803 and 1807 by the British naturalist, chemist and mathematician John Dalton (1766-1844), under the name “Atomic Theory” or “Atomic Postulates”.

This model proposed a scientifically plausible explanation for most of the enigmas of 18th and 19th century chemistry. It postulates that all matter in the world is composed of atoms, that is, that there is a finite number of fundamental particles.

Furthermore, he maintains that simply from the combination of these particles all complex structures of matter are possible. The direct ancestor was the Greeks of classical antiquity.

The postulates of this model are:

  • The subject is constituted of minimal particles indestructible and indivisible called atoms.
  • Atoms of the same element are always identical each other, with the same mass and the same properties. On the other hand, atoms of different elements have different masses and properties.
  • the atoms they are not divided nor can they be created or destroyed during chemical reactions.
  • Atoms of different elements can combine to form compounds in different proportions and quantities.
  • When they combine to form compounds, atoms are arranged according to simple relations described by integers.
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Despite the obvious importance of Dalton's atomic model in the emergence of modern chemistry, it should be noted that This theory has many flaws as noted later.

For example, Dalton thought that gases were monatomic substances, and that molecules were always composed from the smallest possible proportion. This led him to assume that water was composed of a hydrogen atom and another oxygen atom (HO) and to incorrectly calculate the atomic weight of many compounds.

See also: Atomic models

Importance of Dalton's Atomic Theory

Dalton's atomic theory molecule
The model held that atoms combined to form different substances.

Although it was not definitive in the history of chemistry, Dalton proposed the first model, foundational for chemistry. It made it possible to resolve questions on the subject that had no answers at the time.

For example, explained the cause of fixed stoichiometric ratios in chemical reactions that is, why compounds were formed according to fixed amounts of each atom during a reaction.

The possibility of verifying many of Dalton's postulates laid the foundations for future chemistry. Many of his errors remained unresolved until the 19th century, when, for example, the first evidence appeared that atoms, contrary to what Dalton assumed, were divisible.

The great advantage of this model was scientifically explain an immense set of complex facts and diverse compounds from a fairly simple combinatorial theory.

John Dalton Biography

john dalton's atomic theory
John Dalton lived in England between 1766 and 1844.

John Dalton born in Cumberland, England, on September 6, 1766, son of British Quakers (members of a church of Christian origin called the “Church of Friends”). His facilities with mathematics were evident from an early age, but his parents' religion prevented him from making his way to a university, so he had to be educated at the “New School” for religious dissidents that opened in Manchester.

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At that institution he was a professor of Mathematics and Natural Philosophy. He was later elected a member of the Manchester Literary and Philosophical Society, where he presented his first works. Among other findings, discovered color blindness (named in his honor), a visual disease that he suffered from and which consists of the inability to identify colors.

Among his other important theoretical formulations are the Gas Law, the Atomic Model and numerous scientific classifications of vegetables. Finally died July 27, 1844. One of the craters of the Moon bears his name in eternal tribute.

References

  • “Dalton's atomic model” on Wikipedia.
  • “Dalton's atomic model” (video) in AiQuímica.
  • “Dalton's atomic model” in GeoEncyclopedia.
  • “Dalton's Atomic Theory” at Khan Academy.
  • “Dalton's Atomic Theory” (video) in Smart Learning for all.
  • “John Dalton: Atomic Theory” in The Encyclopaedia Britannica.