# John Dalton

### Development of Modern Atomic Theory

## John Dalton's Early Life

John Dalton was born on September 6, 1766, in Eaglesfield, England to a family of Quakers. As a child, he loved to learn and tried to learn everything he could. At age 15 he helped his brother run a Quaker boarding school in Kendal until he was 19. He was principal of the Quaker school until he was 26 years old. After 10 years, he then earned a teaching job in Manchester. One of his students from the school stated, “The boys were all glad to be taught by John Dalton, because he had a gentle disposition; and besides, his mind was so occupied with mathematics, that their thoughts escaped his notice.”

## John Dalton's table of relative atomic weight of some elements With knowing this, he then created a table of relative atomic weight of known elements of the time,including Hydrogen and Oxygen. John thought that water contained one hydrogen atom, and one oxygen atom. Later, he decided the relative weight of oxygen had to be 5.6 times bigger than the hydrogen atom. “All elastic fluids expand the same quantity by heat.” Said Dalton. | ## Quaker boarding school John taught | ## Dalton's Law of Partial Pressures |

## John Dalton's table of relative atomic weight of some elements

## John Dalton's Discovery of the Atom

Dalton wrote a paper over “Daltonism”, or color blindness. Dalton also studied meteorology and philosophy from 1799 to 1801 which led him to figure out what substances were made of. After countless chemical reactions and experiments with gases, he purposed a theory of the atom. He assumed that matter is made up of indestructible, invisible atoms, all atoms in an elements are the same, different chemical properties and weights, compounds form from different atoms combined in whole numbers, and that atoms cannot be created or destroyed.

## John Dalton's Law of Partial Pressure

John was the first person to recognize the pressure of gas mixtures is the sum of the components in a mixture. Dalton’s Law of Partial Pressure states the total pressure of gas mixtures is the sum of pressure of components. The formula is *P1+P2+P3*…and so on. He concluded the idea of partial pressure after seeing that the amount of water vapor that possibly could be absorbed by air at temperature of difference.

## John Dalton's Death

When John Dalton was 71 years old, he has a small stroke. One year later, he had another stroke and could not speak as clearly as he could before. At age 77, he had yet another stroke. He died on July 27, 1844 and was buried in Ardwick cemetery. John Dalton was so appreciated, that 40,000 people payed their respects.