What is 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.

1. What is Dalton’s atomic theory?

It is known as Dalton’s Atomic Theory or Dalton’s Atomic Model for the first model of scientific basis 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 of “Atomic Theory” or “Atomic Postulates.”

This model proposed a scientifically credible explanation to most of the enigmas of chemistry of the 18th and 19th centuries. He postulates that all the matter in the world is made up of atoms, that is, there is a finite number of fundamental particles .

In addition, he argues 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 matter is made up of tiny particles , called indestructible and indivisible atoms .
• The atoms of the same element are always identical to each other, with the same mass and the same properties. In contrast, atoms of different elements have different masses and properties.
• Atoms do not divide , nor can they be created or destroyed during chemical reactions.
• Atoms of different elements can come together to form compounds in different proportions and quantities.
• When combined to form compounds, atoms are arranged according to simple relationships , describable by integers.

Despite the obvious importance of Dalton’s atomic model in the emergence of modern chemistry , it should be noted that this theory has numerous shortcomings , as noted below.

For example, Dalton thought that gases were monoatomic 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 an oxygen atom (HO) and miscalculate the atomic weight of many elements.

2. Importance of Dalton’s Atomic Theory

Although it was not definitive in the history of chemistry, Dalton proposed the first, foundational model for chemistry . It allowed to solve questions on the matter that had no answer at the time.

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

The possibility of checking many of Dalton’s postulates laid the foundations for future chemistry. Many of its errors remained undiscovered until the 19th century, when, for example, the first evidence appeared that atoms, contrary to what Dalton assumed, were divisible. (See: Subatomic particles )

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

3. John Dalton Biography

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

In that institution he was Professor of Mathematics and Natural Philosophy. Later he was elected member of the Philosophical and Literary Society of Manchester, where he presented his first works. Among other findings, he discovered color blindness (named in his honor), which he suffered from.

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