AP US History Long Response Essay

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AP US History Long Response Essay

John Dalton and the Atomic Theory

Among the greatest scientists to have lived was John Dalton who was born in 1766 and whose death occurred in 1844. His greatest contributions to science were his pioneer work in the discovery of the atomic theory as applied in the modern Chemistry and Physics. However, he also had great contributions in the study of color blindness.

Dalton’s atomic theory

Through various research studies, Dalton proved that elements and compounds are composed of the tiniest building blocks known as atoms. The theory was based on various points as are illustrated (“Dalton’s Atomic Theory – John Dalton.” 1)

  1. Elements are formed or composed of tiny units of building blocks called atoms.
  2. First, the atoms of any given element differ from the atoms of another element. Accordingly, the primary difference between these atoms is the different atomic weights shown by either.
  3. Secondly, though his research, Dalton argued that all atoms of a single element had an identical weight.
  4. Chemical compounds are formed by the atoms of different elements combine in a certain ratio. However, the compound formed has a similar relative number of atoms of the constituent elements.
  5. Atoms would neither be created nor destroyed physically or in the chemical process.

Worth appreciating is that Dalton made great discoveries regarding the composition of elements and compounds and that have been the basis of most of the scientific knowledge that has been advanced through chemistry and physics especially about atoms as illustrated through the Dalton Atomic Theory.

Dalton’s experiments illustrated that all atoms of similar elements are identical, but different from one element to another in size and mass. However, Democritus was the first person to have had talked of atoms, although he did not develop the concept of the formation of a theory as Dalton would develop. Therefore, Dalton furthered the ideas on the tiny components of elements through conducting scientific studies. In 1803, Dalton proposed and developed the law of multiple proportions through advancing the works of Joseph Proust and Antoine Lavoisier. His initial experiments with oxygen and tin led him to establish consistence in observation on the combining ratios of the elements. The atomic theory became important in explaining the process of combination and the ratios in which the elements combined.

Another experiment involved the rate at which water absorbed different gases such as nitrogen and carbon dioxide. Accordingly, he established that water would absorb carbon dioxide higher and faster that it did to Nitrogen. His interest in the atomic theory became the foundation of his experiments, and he believed that the theory would explain why the water would absorb the gases in differing ratios. The hypothesis in the experiment was that different complexities and the masses of the gasses would explain the differences noted in the absorption rates.

The outstanding empirical findings in the Dalton’s experiments became the foundation of the development of the atomic theory. Before the experiments, there were only speculations about the possibility of the existence of the tiny blocks called atoms. As such, the atomic theory a developed by Dalton was based on experiments and would, therefore, be used in explaining the composition of elements and how the elements combined to form compounds. However, over the years, Dalton’s atomic theory has had revisions to incorporate and appreciate the existence of isotopes as well as the inter-conversion of energy and mass. In fact, the discovery of sub-atomic particles have been the basis of a challenge to Dalton’s atomic theory and proposition that atoms cannot be subdivided.



Works cited

“Dalton’s Atomic Theory – John Dalton.” John Dalton. 24 Nov. 2015. Web. 5 Jan. 2016. <http://www.johndalton.org/daltons-atomic-theory/&gt;.


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