Biography of John Dalton, the 'Father of Chemistry'

John Dalton (September 6, 1766–July 27, 1844) was a renowned English chemist, physicist, and meteorologist. His most famous contributions were his atomic theory and color blindness research.

Early Life

Dalton was born into a Quaker family on September 6, 1766. He learned from his father, a weaver, and from Quaker John Fletcher, who taught at a private school. John Dalton started working when he was 10 years old and began teaching at a local school at age 12. Within just a few years, despite their lack of higher education, John and his brother started up their own Quaker school. He could not attend an English university because he was a Dissenter (opposed to being required to join the Church of England), so he learned about science informally from John Gough, a mathematician and experimental physicist. Dalton became a teacher of mathematics and natural philosophy (the study of nature and physics) at age 27 at a dissenting academy in Manchester. He resigned at age 34 and became a private tutor.

Scientific Discoveries and Contributions

John Dalton actually published in a variety of fields, including mathematics and English grammar, but he is best known for his science.

• Dalton kept meticulous daily weather records. He rediscovered the Hadley cell theory of atmospheric circulation. He believed air consisted of about 80% nitrogen and 20% oxygen, unlike most of his peers, who thought air was its own compound.
• Dalton and his brother were both colorblind, but this condition had not been officially discussed or studied. He thought the color perception might be due to a discoloration inside the liquid of the eye and believed there was a hereditary component to red-green color blindness. Although his theory about discolored liquid did not pan out, color blindness became known as Daltonism.
• John Dalton wrote a series of papers describing gas laws. His law on partial pressure became known as Dalton's Law.
• Dalton published the first table of relative atomic weights of atoms of the elements. The table contained six elements, with weights relative to that of hydrogen.

Atomic Theory

Dalton's atomic theory was by far his most famous work; many of his ideas have proven to be either completely correct or largely correct. In fact, Dalton's contributions have earned him the nickname, "the father of chemistry."

According to the Science History Institute, Dalton's atomic theories developed during his explorations of meteorology. He discovered, through experiments, that "the air is not a vast chemical solvent as Antoine-Laurent Lavoisier and his followers had thought, but a mechanical system, where the pressure exerted by each gas in a mixture is independent of the pressure exerted by the other gases, and where the total pressure is the sum of the pressures of each gas." This discovery led him to the idea that "the atoms in a mixture were indeed different in weight and “complexity.”

The idea that there are multiple elements, each made up of its own, unique atoms, was absolutely new and quite controversial at the time. It led to experimentation with the concept of atomic weight, which became the basis for later discoveries in physics and chemistry. Dalton's theories can be summarized as follows:

• Elements are made of tiny particles (atoms).
• Atoms of one element are exactly the same size and mass as other atoms of that element.
• Atoms of different elements are different sizes and masses from each other.
• Atoms can't be further subdivided, nor may they be created or destroyed.
• Atoms rearrange during chemical reactions. They may be separated from each other or combined with other atoms.
• Atoms form chemical compounds by combining with each other in simple, whole number ratios.
• Atoms combine according to the "rule of greatest simplicity," which says if atoms only combine in one ratio, it must be a binary one.

Death

From 1837 until his death, Dalton suffered a series of strokes. He continued to work until the day he died, supposedly recording a meteorological measurement on July 26, 1844. The following day, an attendant found him dead beside his bed.

Legacy

Some points of Dalton's atomic theory have been shown to be false. For example, atoms may be created and split using fusion and fission (although these are nuclear processes and Dalton's theory does hold for chemical reactions). Another deviation from the theory is that isotopes of atoms of a single element may be different from each other (isotopes were unknown in Dalton's time). Overall, the theory was immensely powerful. The concept of atoms of elements endures to the present day.

Sources:

• “John Dalton.” Science History Institute, 31 Jan. 2018.
• Ross, Sydney. “John Dalton.” Encyclopædia Britannica, 9 Oct. 2018.