How did an early understanding of gases lead to a better understand of the atom

The early understanding of gases led to the understanding of the atom, because Dalton derived the first theory of the atom through experiments related to a mixture of gases.

Explanation:

Dalton's greatest legacy as a scientist, however, was the development of the first atomic theory. It was through various experiments related to gas mixing and knowledge of the works proposed by Lavoisier that Dalton's atomic theory emerged in 1808. Without the early knowledge of gases, Lavoisier's works would not have been established and Dalton would not be able to establish the basis for understanding the atom.

Dalton's atomic theory was based on experiments, but none of these experiments managed to reveal the atom clearly. So Dalton called the atom the smallest part of matter.