JOHN DALTON: BIOGRAPHY AND MAIN CONTRIBUTIONS - SCIENCE - 2025

John Dalton (1766-1844) was an English chemist, scientist, and meteorologist, best known for his studies on color blindness and his atomic model. He also developed methods for calculating atomic weights and formulated the law of partial pressures. His contributions helped establish the foundations of modern chemistry.

Biography

John Dalton was born on September 6, 1766 in Cumberland, specifically in the city of Eaglesfield, in England. Dalton's family was religious, and they were part of the Religious Society of Friends, whose members were commonly known as Quakers.

This religious society was dissident in nature, that is, they were against the Church as the English nation conceived it at the time, and established their own communities with the pretense of being autonomous in the political and religious spheres.

According to historical records it is known that John actually had five siblings, but of these only two survived; Mary and Jonathan.

Training and work activity

Dalton's first formal education took place at a local school, where he entered at an early age. In that school he stood out as a child with great abilities for mathematics, and very soon he began to teach children younger than him in this same school.

Dalton continued to teach not only at his school, but also from home, and even from the temple that his parents and siblings frequently attended.

This was very important for his family, since very early John was able to contribute to the household finances. However, this contribution was not enough, so he decided to also work in the field of agriculture, doing specific jobs.

Dalton was like that until 1781, when he began working with his brother, who was helping a cousin to run a Quaker school in a nearby town called Kendal.

Interest in science

From this time, John Dalton began to show more evident interest in the sciences, especially in meteorology and in mathematics.

For example, when Dalton lived in Kendal he participated in the calendar called Gentlemen's and Ladies' Diaries, in which he was in charge of writing the solutions to problems that were raised there.

Likewise, in 1787 he began the writing of a meteorological diary, work that he continued to carry out for more than five continuous decades. At the end of Dalton's life, it was possible to collect more than 200,000 observations that this scientist had made in the Manchester area.

Three years later, in 1790, John considered the option of studying medicine or law, but at that time people who belonged to dissident religious associations were banned from studying or teaching at universities in England.

So Dalton stayed in Kendal for three more years. It was in 1793 when he moved to Manchester, where he had the opportunity to teach at the New Manchester School, a special space for members of religious dissident associations.

Dalton managed to teach natural philosophy and mathematics there as a result of the intervention of his informal teacher: John Gough. Thanks to Gough, who was blind, Dalton acquired much of his knowledge in the field of science.

Work in the Philosophical and Literary Society of Manchester

New School was Dalton's workplace for seven years. At this time he was also appointed a member of the Manchester Literary and Philosophical Society.

It was before this society that Dalton presented his first work related to the difficulty to perceive colors, a condition that he himself suffered.

This line of research was undervalued while Dalton lived, but later on the merit was recognized for the very lengthy methodology used in the study, which is why the phenomenon related to the inability to distinguish colors ended up being called color blindness.

In 1800 he had to resign, because the economic situation of this school was very critical. From then on, Dalton began to seek employment as a private teacher.

At the same time, during that year he was also appointed secretary of the Manchester Literary and Philosophical Society, a position from which he devoted himself to giving various lectures, specifically related to the characteristics of the pressure of water vapor.

For his contributions, in 1822 Dalton received an appointment as a member of the Royal Society of London. After three years of this mention, in 1825, he received the gold medal awarded by this same institution.

Death

John Dalton's death occurred on July 27, 1844, when this scientist was 77 years old. The reason for the death was a heart attack.

His death was an event considered important for the society of the time, so much so that he received the honors intended only for the kings of England. Dalton's funeral was attended by more than 400,000 people.

Autopsy

Dalton had predisposed them to keep their eyes after his death, so that they could study them and verify the real cause of the condition related to the inability to distinguish colors correctly.

Indeed, after his death, Dalton's body was subjected to an autopsy and the studies done on his eyes determined that the failure related to the perception of colors was not related to a specific disability in the eye, but rather to a deficit in vision. sensory capacity.

In fact, by doing a comprehensive study of Dalton's eyes, specialists were able to note that the condition he had corresponded to a much less common disease than what was later known as color blindness.

Dalton had deuteranopia, a condition in which there is an absence of photosensitive cells that react with medium wavelengths, which are located in the photoreceptor layer of the retina. This is why Dalton, in life, could only distinguish three shades: blue, yellow and purple.

Main contributions

Theory of the atom or atomic

In the image above, a summary of Dalton's model is represented: the atoms would be indivisible, indestructible and homogeneous tiny spheres.

This was his most important contribution to science. Although some of his research has been shown to be not entirely true, his theory that matter is made up of atoms of different masses that combine in simple proportions to form compounds is the cornerstone of modern physical science.

This theory contributes to current research in nanotechnology, which is based mainly on the manipulation of atoms.

He came to the conclusion that each form of matter (solid, liquid or gas) is made up of small individual particles and he called each particle an atom, inspired by the theory of the Greek philosopher Democritus.

John Dalton became the first scientist to explain the behavior of atoms according to their weight.

His theory was that the atoms of different elements could be distinguished based on their different atomic weights. Their masses were not entirely precise, but they form the basis of the current periodic classification of the elements.

Atomic weights

In his investigations he concluded that atoms could not be created, destroyed, or divided. He observed that the molecules of an element are always made up of the same proportions, except for the water molecules. Atoms of the same element are equal to each other and atoms of different elements have different weights.

This theory was finally proven to be untrue, since it was possible to divide atoms through the process of nuclear fission. It was also shown that not all atoms of the same element have the same mass, since there are different isotopes.

Law of multiple proportions

From all the studies, investigations and observations that he carried out on gases and meteorology, he arrived at the theory of the law of multiple proportions, which established that the weights of the elements always combine with each other in more than one proportion with a fixed amount forming different compounds.

If the fixed quantity of one element is combined with different variable quantities of another element, the relationship between them is always simple whole numbers.

Law of partial pressures (Gas Law)

In 1803 he formulated this law that summarizes the quantum laws of chemistry. Thanks to his numerous trials and experiments, he was able to make known to the world his theory that if two gases mix with each other, they behave as if they were independent.

The first gas does not attract or repel the second gas, it just behaves as if this second gas did not exist. He concluded that if several gases that do not react with each other are mixed, the total pressure of them is the sum of the pressures of each gas.

Today, divers use Dalton principles to assess how pressure levels at different ocean depths will affect the air and nitrogen in their tanks.

Meteorology: Atmospheric pressure

Dalton first tested the theory that rain is not caused by a change in atmospheric pressure, but by a decrease in temperature.

He kept daily records of the weather conditions throughout his life, collecting more than 200,000 notations about the climate of Manchester. The first book he published was in this field, in 1793, under the title Observations and meteorological tests.

He developed several instruments and studied the northern lights, concluding that they are caused by the magnetism exerted by the Earth.

British Association for the Advancement of Science

John Dalton was one of the founders of the British Association for the Advancement of Science. He was also elected as a member of the Royal Society of London in 1822 and in 1826 he received the gold medal from the Royal Society of London.

The legacy after his death

After his death, John Dalton left all his wisdom and research embodied in his books and essays. In honor of all their research, many chemists today use the Dalton (Da) unit to refer to a unit of atomic mass.

The division of the atom in the 20th century might not have been possible without his research on the atomic composition of molecules. A lunar crater bears his name: Dalton Crater.

Main works

• Observations and essays (1793)
• Elements of English Grammar (1801)
• Extraordinary facts related to the vision of colors (1794)
• A new system of chemical philosophy (1808)

References

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3. Searchbiografias.com team. (sf 12, 1999). John Dalton. Retrieved on April 26, 2017, from Buscabiografias.com.
4. (07/14/2014). Atomic Theory. Retrieved on April 26, 2017, from chem.llibretext.org.
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